Simulations Of The Effects Of The Climate Change

SIMULATIONS OF THE EFFECTS OF CLIMATE CHANGE Ashok Malik g RAJAT PUBLICATIONS NEW DELHI - 110002 (INDIA) RAJAT PUBL...

Author: A. Malik

19 downloads 537 Views 17MB Size Report

This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form

DOWNLOAD PDF

SIMULATIONS OF THE EFFECTS OF CLIMATE CHANGE

Ashok Malik

g RAJAT PUBLICATIONS NEW DELHI - 110002 (INDIA)

RAJAT PUBLICATIONS 4675/21 ,Ansari Road, Daryaganj New Delhi- 110002 (India) Phones: 23267924,22507277 E-mail: [email protected]

Simulations of the Effects of Climate change © Reserved First published, 2008 ISBN 978-81-7880-344-9

[ The responsibility for facts stated opinion expressed or conclusions reached and plagiarism, if any, in this volume is entirely that of the Editor. The publisher bears no responsibility for them whatsoever.]

PRINTED IN INDIA Published by Mrs. Seema Wasan for Rajat Publications, New Delhi and Printed at Asian Offset Press, Delhi.

Contents

l.

Global Climate Change and Carbon Cycling

2.

Greenhouse Effect and Ecosystems

19

3.

Prediction of Climate Change

49

4.

Global Biogeochemical Carbon Cycle

65

5.

Variations in Climate Change

103

6.

Dynamics of Ecological Systems

125

7.

Modelling Techniques

141

8.

Evaluation of Terrestrial Systems

155

9.

Assessment of Freshwater Quality

175

1

10. Ecological Risk Assessment

193

11. Environmental Monitoring

203

12. Costs of Climate Change Mitigation

235

Bibliography

271

Index

273

1 Global Climate Change and Carbon Cycling The simultaneous changes in the chemistry of the atmosphere and the climate are expected to affect both the function and the structure of terrestrial ecosystems. Functional changes may include changes in processes such as photosynthesis, plant respiration and decomposition. Structural changes may be of various types, including changes in the distribution of carbon and nitrogen between the plant and soil pools, changes in the species composition within an ecosystem, and changes in the distribution of major vegetation groups or biomes. Process-based models have been used in regional studies to evaluate the functional responses of terrestrial ecosystems to changes in climate. One of these models, the terrestrial ecosystem model (TEM), has been used at the global scale to explore how carbon and nitrogen cycling in terrestrial ecosystems might change according to predictions of climate change made by several general circulation models (GCMs). A dominant feature of GCM-predicted climate for a doubled CO2 atmosphere is an increase in mean surface temperature of the globe; precipitation and cloudiness are expected to increase in some areas and decrease in others,

2

Simulations of the Effects of Climate Change

and there is disagreement among the output of GCMs about the spatial distribution of these changes. Elevated temperature may affect carbon cycling in ecosystems in a variety of ways. It may enhance decomposition of soil organic matter to increase the loss of carbon from the soil. Enhanced decomposition may also increase nitrogen availability through higher rates of nitrogen mineralisation. Uptake of this nitrogen by vegetation may enhance NPP. Decreases in NPP may result from elevated temperature by reducing soil moisture or by increasing respiration. Because the ability of vegetation to incorporate elevated CO2 into production depends on the nutrient and water status of the vegetation, climate change may influence carbon cycling in ecosystems by altering nutrient availability and soil moisture. The TEM ha"s been developed to evaluate how climate change influences simultaneous interactions among the carbon, nitrogen, and water cycles in ecosystems. Terrestrial Ecosystem Model (TEM)

The terrestrial ecosystem model (TEM) is a process-based ecosystem simulation model that uses spatially referenced information on climate, elevation, soils, vegetation, and water availability to make monthly estimates of important carbon and nitrogen fluxes and pool sizes. For each monthly time step in a model run, NPP is calculated as the difference between gross primary production (GPP) and plant respiration (RA). The calculation of GPP considers simultaneous interactions among temperature, light, CO2, water, and nitrogen availiability. Therefore, the response of GPP to elevated CO2 is potentially constrained by the availability of light, water, and nitrogen. The calculation of RA considers both maintenance respiration and construction respiration.

Global Clinulte Change and Carbon Cycling

3

The data sets used to drive TEM are gridded at a resolution of 0.5 0 latitude by 0.5 0 longitude. The sources for the climate data (air temperature, precipitation, and cloudiness), elevation, vegetation, and soil texture are described elsewhere; the climate data represent long-term averages. Hydrological inputs for TEM are determined with a water balance model that uses the climate, elevation, soils, and vegetation data. The application of TEM to a grid cell requires the use of monthly climatic and hydrological data and the soiland vegetation-specific parameters appropriate to the grid cell. Although many of the vegetation-specific parameters in the model are defined from published information, some are determined by calibrating the model to the steady-state fluxes and pool sizes of an intensively studied field site. Most of the data used to calibrate the model for the vegetation types considered in this study are documented elsewhere. In most of the analyses, TEM has been calibrated to the soil organic carbon and nitrogen found to approximately 1 m depth at the calibration site, the 'I m' calibration. Table 1 Areal extent of grasslands and coniferous forests

Area (106 km2) Grasslands Tall Short Total Conifer forests Boreal Forest Temperate conifer Temperate mixed Total All ecosystems

Cells

3.6 4.7 8.3

1557 2050 3607

12.2 2.4 5.1 19.7

7406 1081 2250 10737

127.3

56090

4


Global Grassland Communities and Conifer Forests

The global distribution of grasslands and conifer forests, which represents 22% of the area occupied by the terrestrial biosphere, is determined from a global georeferenced data base (0.5 0 spatial resolution) of potential vegetation developed from extant maps. The global grassland communities are aggregated into two major vegetation types, tall and short grasslands, based on the relative height of the dominant vegetation. Tall grasslands contain grasses with heights greater than 1 m and occur in more mesic sites than short grasslands. Although the northern meadow-steppe of Euro-Asia contains relatively 'short' species, the dynamics of this community are thought to be similar to the tall grass prairie of North America. Therefore, northern meadowsteppes have been classified as tall grassland. Both grassland types are found throughout the temperate and tropical zones. Do not consider grasslands found in savannas of the temperate and tropical regions.

Table 2 Estimates by the TEM of annual NPP for grasslands and conifer forests in the terrestrial biosphere at an atmospheric CO2 concentration of 355 ppmv (parameterised for 1 m soil carbon) Total NNPa Grasslands Tall Short Total Conifer forests Boreal forest Temperate conifer Temperate mixed Total

Mean NPPb

Max. NPPb

Min. NPPb

1.2 1.0 2.2

335 214 267

756 438 756

136 72 72

2.9 1.1 3.4 7.4

238 465 669 378

434 704 1066 1066

124 208 231 124

a Units are Pg C( 1015 g C ) yr·! b Units are g Cm-2 yr· t

Global Climllte Change and Carbon Cycling

5

Conifer forests are aggregated into three major vegetation types based on physiognomy and climate: boreal forests, temperate mixed forests, and temperate conifer forests. Boreal forests (located mainly in Canada and Alaska, northern Europe, and the Commonwealth of Independent States) contain both conifer and deciduous dominant species and represents 62% of all potential conifer forests. The next abundant forest type, temperate mixed forests (26%), also contains both conifer and deciduous dominant species and is found mainly in the United States, Europe, and China. Temperate conifer forests have a global distribution similar to temperate mixed forests, but are also found in many mountainous regions. Contemporary Climate

To estimate fluxes and pools of grasslands and conifer forests for 'contemporary' conditions, applied TEM at 355 ppmv CO2 using the long-term climate data with the 1 m calibration. For grasslands, TEM estimates an annual NPP of 2.2 Pg C (10 15 g C; Table 2). The vegetation and soil carbon estimates for grassland are 3.4 Pg C (Table 3) and 75.7 Pg C (Table 4). Although conifer forests occupy 2.4 times the area of grasslands, the estimated annual NPP is 3.4 times that of grasslands (7.4 Pg C; Table 2), vegetation carbon is 84.3 times greater (286.7 Pg C; Table 3), and soil carbon is 3.1 times greater (231.4 Pg C; Table 4). The higher vegetation carbon of conifer forests reflects the ability of forests to store carbon in woody tissue. Per unit area, TEM estimates that total carbon storage in global conifer forests is 2.8 times that in global grasslands.

Simuilltions of the Effects of Climate Chilnge

6

Table 3 Estimates by the TEM of vegetation carbon for grasslands and conifer forests in the terrestrial biosphere at an atmospheric CO2 concentration of 355 ppmv (parameterised for 1 m soil carbon) Total carbona Grasslands Tall

Short Total Conifer forests Boreal forest Temperate conifer Temperate mixed Total

Mean carbonb Max. carbonb Min. carbonb 1.8 1.6 3.4

512 337 413

1156 690 1156

208 113 113

118.5 90.7 77.5 286.7

9739 37803 15224 14586

17739 57196 24269 57196

5033 16939 5261 5033

a Unites are Pg C( 1015 g C ) yr-1 . b Unites are g C m o2 yro1

Table 4 Estimates by the TEM of soil carbon for grasslands and conifer forests in the terrestrial biosphere at an atmospheric CO2 concentration of 355 ppmv (parameterised for 1 m soil carbon) Total carbona Grasslands Tall Short Total Conifer forests Boreal forest Temperate conifer Temperate mixed Total

Mean carbonb Max. carbonb Min. carbonb

58.4 17.3 75.7

16211 3701 9156

23714 5129 23714

8039 1689 1689

132.3 45.1 54.0 231.4

10878 18804 10612 11777

12189 28219 15606 28219

4578 5097 6285 4578

a Unites are Pg C( 1015 g C ) yro1 b Unites are g Cmo2 yr1

However, the area-based estimates by TEM may be appropriately compared. The grassland NPP estimate of

Global Climllte Change and Carboll Cycling

7

267 g C m-2 yr-l by TEM (Table 2) is similar to the estimate of 225 g C m- 2 yr- l by Whit taker and Likens for temperate grasslands_ However, the vegetation carbon estimate of 413 g C m-2 (Table 3) is substantially lower than their estimate of 700 g C m-2 _ The soil carbon estimate of 9156 g C m-2 by TEM for grasslands is similar to 10692 g C m-2 (417 Pg / 3900 106 ha) reported by Ojima et aL for soil carbon to 1 m depth in potential world grasslands. The TEM estimate of 238 g C m-2 yr- l for boreal forest NPP (Table 2) is substantially lower than the Whittaker and Likens estimate of 360 g C m-2 yr- l • However, the estimate for boreal forest vegetation carbon (9739 g C m2 2; Table 3) is similar to their estimate of 9000 g C m- • The TEM estimate of 10878 g C m-2 for boreal forest soil carbon (Table 4) is lower than the 14900 g C m- 2 estimate of Schlesinger; the TEM estimate is lower because the model does not represent anaerobic processes that C3.use higher carbon storage to occur in northern peatlands. The Whittaker and Likens NPP estimate of 585 g Cmyr- l for temperate evergreen forest is intermediate between the TEM estimates for temperate conifer and temperate mixed forest. Their estimate of 16000 g Cm-2 for vegetation carbon of temperate evergreen forest is similar to the TEM estimate of 15224 g Cm-2 for temperate mixed forest; the TEM estimate for temperate conifer forest (37 803 g Cm-2; Table 3) is much higher because the calibration site is an old-growth forest in the Pacific Northwest of the United States. 2

The Schlesinger estimate of 11 800 g Cm-2 for temperate forest soil carbon is similar to the TEM estimate for temperate mixed forest (10612 g Cm-2; Table 4). Again the TEM estimate for temperate conifer forest (18804 g Cm2; Table 4) may be higher because the calibration site is an old-growth forest.

8


Development' of Future Climate Scenarios

We obtained the output of two general circulation models (GCMs) from the National Centre for Atmospheric Research. The simulations estimate equilibrium climates that correspond to a doubling of the atmospheric CO2 concentration and include one from the Geophysical Fluid Dynamics Laboratory and one from Oregon Stale University. The GFDL GCM represents a high temperature impact scenario and predicts increases of 4.9 °C for the grassland biome and 6.2 °C for the conifer forest biome. The OSU GCM represents a low impact scenario and predicts increases of 3.2 and 3.4 °C for the grassland and conifer forest biomes. Precipitation for grasslands is predicted to increase by both GCMs with larger increases predicted by OSU (82.0 mm) than by GFDL (46.5 mm). Precipitation is also predicted to increase for conifer forests, with similar increases predicted by GFDL (67.7 mm) and OSU (75.9 mm). Cloudiness is predicted by GFDL and OSO to decrease 1.4 and 2.1% for grasslands, respectively. For conifer forests, cloudiness is predicted by GFDL to increase 0.6%, but by 050 to decrease 2.5%. To help separate the effects of changes in CO2 concentration from those of the GCM climates on estimates of NPP and carbon pools, performed a factorial experiment with the 1 m calibration of TEM involving two levels of CO2 (312.5 and 625.0 ppmv) and three climate scenarios (contemporary and the two GCM climates). Responses to Doubled Carbon Dioxide

For doubled CO2 and no climate change, TEM predicts that NPP, vegetation carbon, and soil carbon for individual grid cells of grasslands and conifer forests either do not change or increase. For global grasslands, TEM predicts that NPP increases 0.2 Pg C (9.1 %; Table 5), vegetation


9

carbon increases 0.3 Pg C (9.1 %; Table 6), and soil carbon increases 3.4 Pg C (4.3%; Table 7). For global conifer forests, TEM predicts NPP to increase 0.4 Pg C (5.5%; Table 5), vegetation carbon to increase 17.5 Pg C (6.2%; Table 6), and soil carbon to increase 9.0 Pg C (3.9%, Table 7). Thus, for doubled CO2 and no climate change conifer forests are potentially a more responsive carbon sink than grasslands. The response of conifer forest NPP and soil carbon to elevated CO2 predicted by TEM depends on the degree to which NPP is limited by nitrogen availability. In moist regions of temperate conifer forest, where NPP is predicted by TEM to be limited by nitrogen availability more than by soil moisture, there is little response to elevated CO2• In dry regions elevated CO2 promotes enhanced water-use efficiency in TEM which translates into increased NPP. Because most of the conifer forest region considered in this study is moist conifer forest, i.e. in the boreal and temperate-mixed regions, the enhancement of NPP and soil carbon in response to elevated CO2 is small. Responses to Changes in Climate

With no change in CO2 concentration, TEM predicts for both the GFDL and OSU climates that responses of NPP, vegetation carbon, and soil carbon for individual grid cells of grasslands and conifer forests can be either positive or negative. For global grasslands, TEM predicts annual NPP to increase 0.4 Pg C (18.2%) for the GFDL climate and 0.2 Pg C (9.1 %) for the OSU climate (Table 5). Vegetation carbon is predicted to increase 0.7 Pg C (21.2%) for the GFDL climate and 0.6 Pg C (18.2%) for the OSU climate (Table 6). For the GFDL climate, soil carbon decreases 3.8 Pg C(5.1 %; Table 7). In contrast, soil carbon is predicted to increase slightly for the OSU climate (0.7 Pg C, 0.9%; Table 7).

10


For global conifer forests, TEM predicts annual NPP to increase 1.0 Pg C (13.7%) for the GFDL climate and 0.9 Pg C (12.3%) for the OSU climate (Table 5). Increases in vegetation carbon are slightly higher for the GFDL climate (38.1 Pg C, 13.5%; Table 6) than for the OSU climate (34.4 Pg C, 12.2%; Table 6). The decreases in soil carbon predicted for the GFDL climate (31.3 Pg C, 13.7%; Table 7) are more than three times those predicted for the OSU climate (9.2 Pg C, 4.0%; Table 7). Thus, for the climates considered with no change in CO 2, grasslands are potentially either carbon sources or sinks and conifer forests are potentially sinks. The sink strength is greater for conifer forests than grasslands because of the ability of forests to store carbon in woody tissue. In grasslands, and in boreal and cool-moist temperate

regions of conifer forest, elevated temperature generally increases the NPP predicted by TEM through enhanced nitrogen availability. Schimel et al., based on 50-year simulations of climate change with the CENTURY model for sites in the Great Plains, attributed increased NPP to elevated nitrogen availability because of enhanced decomposition, but indicated that nitrogen losses related to higher decomposition could decrease NPP in the long term. Burke et al. applied the doubled-C0 2 climate predicted by the Goddard Institute for Space Studies (GISS) GCM to the central Great Plains and reported that above ground NPP for the region increased less than 10% after 50 years of simulation with CENTURY. This result is similar to the equilibrium response predicted by TEM for the OSU climate applied to global grasslands. Linked models of forest productivity and soil processes have also predicted that elevated temperature enhances conifer growth through increased nitrogen availability for simulations at specific sites.

11

Global Clinuzte Change and Carbon Cycling

Decreases in NPP may result from elevated temperature by reducing soil moisture. This mechanism primarily affects the NPP response of TEM in dry regions of conifer forest. Other models have predicted that elevated temperature may increase evapotranspiration to decrease forest growth in both dry and wet regions of present-day conifer forest. Elevated temperature may also decrease NPP by enhancing respiration costs relative to carbon uptake. This mechanism has been observed to primarily affect the NPP response of TEM in warm moist regions of temperate conifer forest; it has also been observed to be an important factor influencing the NPP response predicted by the Forest-BGC model to elevated temperature at a site in warm-moist temperate forest. Because elevated temperature influences processes that can both enhance or decrease the NPP predicted by TEM, the NPP response to the high-temperature GFDL climate did not substantially differ from the NPP response to the lowtemperature OSU climate.

Table 5 Response of NPP (1015 9 C yrl) by region for experiment involving two levels of atmospheric C02 and three levels of climate (parameterised for 1 m soil carbon) Climate: CO2 concentration (ppm): Grasslands Tall Short Total Conifer forests Boreal forest Temperate conifer Temperate mixed Total

Contemporary

GFDLI

OSU

312

625

312

625

312

625

1.2 1.0 2.2

1.3 1.1 2.4

1.4 .12 2.6

1.5 1.4 2.9

1.3 1.1 2.4

1.4 1.2 2.6

2.9 1.1 3.3

2.9 1.2 3.6

3.8 1.1 3.4

4.4 1.3 4.0

3.5 1.1 3.6

3.7 1.3 4.0

7.3

7.7

8.3

9.7

8.2

9.0


12

The NPP response of TEM to elevated temperature influences the response of vegetation carbon; increased NPP translates into increased vegetation carbon for both the GFDL and OSU climate scenarios. Linked models of forest productivity and soil processes have also predicted increased above ground vegetation carbon in response to climate warming for conifers of both the temperate and boreal region, although the response depends on whether or not soil moisture is affected.

Table 6: Response of vegetation carbon (1015 g C) by region for experiment involving two levels of atmospheric CO 2 and three levels of climate (parameterised for 1 m soil carbon) Climate: GFDLI Contemporary C02 concentration (ppm): 312 625 312 625 Grasslands 2.3 Tall 1.8 1.9 2.1 2.2 Short 1.5 1.7 1.9 Total 3.3 3.6 4.0 4.5 Conifer forests Boreal forest 117.9 120.5 154.9 178.2 98.0 88.6 108.9 Temperate conifer 88.3 Temperate mixed 75.7 80.9 76.5 91.9 Total 281.9 299.4 320.0 379.0

OSU 312

625

2.1 1.8 3.9

2.2 2.0 4.2

144.7 89.7 81.9 316.3

151.5 104.7 91.7 347.9

Table 7 Response of soil carbon (1015 g C) by region for experiment involving two levels of atmospheric CO2 and three levels of climate (parameterised for 1 m soil carbon) Climate: CO2 concentration (ppm): Grasslands Tall Short Total

Contemporary

GFDLI

OSU

312

625

312

625

312

625

58.0 17.0 75.0

60.0 18.1 78.1

54.9 16.3 71.2

59.6 18.4 78.0

58.7 17.0 75.7

61.7 18.4 80.1


13

Conifer forests Boreal forest 131.9 Temperate conifer 44.3 Temperate mixed 53.1

134.2 48.0 56.1

114.1 37.3 46.7

129.5 45.0 54.7

128.6 40.8 50.7

133.9 46.4 55.6

Total

238.3

198.1

229.2

2201

235.9

229.3

The response of soil carbon to elevated temperature will depend on the NPP response, which influences inputs into the soil, and on the decomposition response per unit soil carbon, which influences CO2 losses from the soil organic pool.

In TEM, if elevated temperature does not substantially decrease available soil moisture, then it will increase decomposition per unit soil carbon. Elevated temperature is predicted by TEM to decrease soil carbon for the hightemperature GFDL climate, but not for the lowtemperature OSU climate. Schimel et a1. indicated that soil carbon levels decreased in response to elevated temperature at sites in both the northern and southern Great Plains of the United States. Similarly, Burke et a1. reported that soil carbon levels of the central Great Plains decreased approximately 3% after running CENTURY for SO years with the GISS climate. This decrease is intermediate to the responses predicted by TEM for the GFDL and OSU climates; the temperature increase predicted by the GISS climate is intermediate between the GFDL and OSU climates. Elevated temperature is predicted by TEM to decrease the soil organic pool of conifer forests for both the GFDL and OSU climates, with greater decreases predicted for the high-temperature GFDL scenario. A linked model of boreal forest productivity and soil processes also predicts that soil organic carbon of boreal conifers decreases in response to climatic warming.

14

Simulations of the Effects of Climllte Change

Responses to Changes in Climate and Carbon Dioxide

With changes in both climate and CO2 concentration, TEM predicts that responses of NPP, vegetation carbon, and soil carbon for individual grid cells of grasslands and conifer forests may be positive or negative. For global grasslands, TEM estimates annual NPP to increase 0.6 Pg C (27.3%) for the GFDL climate (Table 5). The predicted increases for the OSU climate are slightly less (0.4 Pg C, 18.2%; Table 5)., Vegetation carbon increases 1.2 Pg C (36.4%) for the GFDL climate and 0.9 Pg C (27.3%) for the OSU climate. The predicted increases in soil carbon are less for the GFDL climate (3.0 Pg C, 4.0%; Table 7) than for the OSU climate (5.1 Pg C, 6.8%; Table 7). For global conifer forests, TEM predicts annual NPP to increase 2.4 Pg C (32.9%) for the GFDL climate, which is about 40% more than the 1.7 Pg C (23.3%) increase for the OSU climate. Increases in vegetation carbon predicted for the two climates show a similar pattern; for the GFDL climate, the 97.1 Pg C increase (34.4%) is more than 40% higher than the 66.0 Pg C increase (23.4%) predicted for the OSU climate (Table 6). Soil carbon decreased slightly for the GFDL climate (0.1 Pg C; < 0.1 %; Table 7), but increased for the OSU climate (6.6 Pg C; 2.9%; Table 7). Thus, for the climates considered with elevated CO 2 concentration, conifer forests are potentially much stronger carbon sinks than grasslands because of the ability to store carbon in woody biomass. The response of NPP to elevated CO 2 and temperature predicted by TEM is influenced by moisture availability. In moist regions of temperate forest, elevated temperature enhances decomposition to increase nitrogen availability. The increased nitrogen availability allows the vegetation to generally 'incorporate elevated CO2 into _production, but the overall effect on NPP is sensitive to the plant respiration response. In contrast, the FOREST -

Global ClimJlte Change a1ld Carbon Cyc1iug

15

BGC model predicts a slight decrease in NPP for a site in warm-moist conifer forest because the enhanced respiration costs of elevated temperature more than offset the photosynthetic gains from elevated CO2, In dry regions of temperate forest, NPP is predicted by TEM to increase because enhanced carbon uptake in response to elevated CO2 generally more than compensates for decreased soil moisture or increased plant respiration caused by elevated temperature. Similarly, fO{ a site in a dry conifer forest the ForestBGC model predicts increased NPP in response to elevated temperature and CO2 because photosynthetic gains more than offset respiration costs. The increases in NPP predicted by TEM for conifer forests in response to elevated temperature and C02 translate into increased vegetation carbon for both the GFDL and OSU climates. However, the enhanced NPP is able to compensate for the increased decomposition per unit soil carbon for the lowtemperature OSU climate, but not for the GFDL climate. Thus, soil carbon increases are predicted for the OSU climate and decreases for the GFDL climate. Table 8 Response of soil carbon (1015 g C) in tall grasslands and temperate conifer forest for the 1 ill and 20 cill calibrations in the experiment involving two levels of atmospheric CO2 and three levels of climate Climate:

Contemporary

CO2 concentration (ppm): 312 Tall grasslands 1 m calibration 58.0 20 cm calibration 17.4 Temperate conifer forests 1 m calibration 44.3 20 em calibration

12.7

GFDLI

OSU

625

312

625

312

625

60.0 18.0

54.9 16.6

59.6 18.0

58.7 17.6

61.7 18.6

48.0

37.3

45.0

40.8

46.4

13.8

10.7

12.9

11.7

13.3

16


Sensitivity to the Calibration Depth of Soil Carbon

The responses of NPP and vegetation carbon to changed climate or CO2 do not demonstrate any sensitivity to the calibration depth of soil carbon for either tall grasslands or temperate conifer forests. However, the ,absolute responses of soil carbon for the 1 m calibrations of tall grasslands and temperate conifer forest are approximately three to four times larger than for the 20 cm calibrations (Table 8), Although the absolute response of soil carbon is always greater for the 1 m calibration, the proportional responses are essentially identical for both the 1 m and 20 cm calibrations. For models that make equilibrium estimates, these results indicate the importance of identifying at the calibration site the soil carbon that is likely to be actively decomposing over the time frame of interest. For climate change studies involving a doubled CO2 atmosphere, the appropriate time scale is decades to centuries. The inclusion of soil carbon that turns over on the time scale of millennia ('old carbon') will overestimate the response of soil carbon. The CENlURY model estimates soil carbon to a depth of 20 cm. This depth may be approximately appropriate for identifying the relevant soil carbon in grasslands where most inputs are near the surface, but in forests the rooting zone may be much deeper than 20 cm. Because both recent and old carbon may occur at all depths in a forest soil, depth may not be the best metric to identify the actively decomposing soil carbon that is appropriate to doubled CO2 climate studies. Spatial Scale for the Comparison of Model Responses

During the next century, substantial simultaneous changes are predicted to occur jn several climatic variables


17

including CO2 temperature, precipitation, and cloudiness. To assess the infh.;.,-nce of these changes on regional carbon cycling, it is desirable to represent how the interactive effects of climate change and elevated CO2 influence ecosystem processes in a spatially continuous manner. Although several models have been used to study the potential effects of climate changes on carbon cycling in grasslands and conifer forests, few have been used to study the interactive effects of climate with elevated CO'. Also, most investigations have focused on potential responses at specific sites rather than the responses at larger spatial scales; the results of site-specific investigations can appear contradictory so that responses at the regional scale are difficult to assess. The spatial scale is considered at two resolutions. The fine resolution is 'site', which may include a grid ceB or polygon for whiClh the climate variables were treated in the study as having no spatial variability. The coarse spatial scale is 'regional', which define as an aggregation of grid cells or polygons. The CENTURY model has been used to study potential responses of NPP and soil carbon in the grassland biome at both the site and regional scales. The region considered by Burke et al. is the central Great Plains of the United States, which is contained within the total grassland region considered by TEM. The climatic responses predicted by both models are consistent at both the site and the regional spatial scales, although the regions considered by CENTURY and TEM are not identical. Of the CENTURY studies, only Ojima et al. consider responses to changes in both climate and CO2; these are consistent with the TEM results at the site scale.

18


The application of models to study the potential responses of conifer forests has primarily focused on the effects of climate change at the site scale. The results of these studies are consistent with responses predicted by TEM at the site scale, but only one of the studies has examined the response of soil carbon.

2 Greenhouse Effect and Ecosystems Significant changes of the marine system on a global scale are less well documented, but it has been shown clearly that man-made pollutants are invading even the deep sea. Air and water pollution are generally increasing. It is, of course, hardly surprising that the presence of almost 5000 million people on Earth is altering the natural systems significantly. Some such changes must be accepted in order to permit the exploitation of the natural resources on which man is dependent. What do the changes of the terrestrial and marine ecosystems and other ongoing changes mean to man in a long-term perspective? It is important to keep in mind throughout the following discussion that the CO2 problem, or rather the problem of a possibly changing climate due to emissions of greenhouse gases into the atmosphere, cannot be considered in isolation. It is one of many important environmental problems that must be addressed but in a long-term perspective probably the most important one. Ute realisation that the climate might change as a result of emissions of carbon dioxide into the atmosphere is not new. Arrhenius pointed out that the burning of fossil fuels might cause an increase of atmospheric CO2 and

20


thereby change the radiation balance of the Earth. During the 1930s Callendar for the first time convincingly showed that the atmospheric CO2 concentration was increasing. Earlier attempts had not been successful primarily due to non-representative sampling. The problem was revived again by C. G. Rossby in the 1950s, who was the driving force behind the initiation of CO2 measurements in Scandinavia, and by R. Revelle, who was instrumental in getting C. D. Keeling engaged in the observational programmes on Mauna Loa, Hawaii, and at the South Pole in 1957-58. At about the same time Revelle and Suess presented the first more careful assessment of the likely future CO2 increases due to fossil fuel combustion. This was followed by a more elaborate analysis by Bolin and Eriksson. The observations begun in 1958 have clearly shown that the concentration of carbon dioxide (C02 ) in the atmosphere has increased from about 315 ppmv then to about 343 ppmv in 1984. Approximately the amounts of CO2 that have been emitted into the atmosphere by fossil fuel combustion and changing land use (deforestation and expanding agriculture) and can relate the observed increase of atmospheric CO2 to these human activities. Since a continued increase of the atmospheric CO2 concentration might lead to changes of the global climate, it is essential to be able to project the likely future concentrations that may occur due to various possible rates of CO2 emission. The reason for concern about climatic effects is the so-called 'greenhouse effect' of CO 2 • While CO 2 is transparent to incoming short wave radiation from the Sun, it absorbs outgoing long wave radiation and re-emits this energy in all directions. Therefore, an increase of the atmospheric CO2 concentration leads to a warming of the Earth's surface and lower atmosphere. In addition, it is


21

becoming increasingly clear that a number of other greenhouse gases in the atmosphere similarly affect the radiation budget. Their concentrations are also changing as a result of natural and human causes. Since increased concentrations of CO2 as well as of these other greenhouse gases all lead to a warming of the Earth's surface and lower atmosphere, the estimated climatic effects and further impacts (e.g. on sea level and agriculture) must be considered as a result of a combined effect of these potential origins of the warming. However, in order to be able to make estimates of their relative contributions to the warming and associated climatic changes at any given time, their effects are studied separately. NUMEROUS ASSESSMENTS OF THE

CO2 PROBLEM

The first international assessment of the CO 2 issue organised by UNEP, WMO and ICSU resulted from an expert meeting held in Villach, Austria, in November 1980. The projection of future fossil fuel use made at that meeting was largely based on a scenario developed at the Institute for Energy Analysis, Oak Ridge (USA). The projection of the atmospheric carbon dioxide concentration in 2025 was made by assuming that 40-55% of the total emissions would remain in the atmosphere (the so-called airborne fraction). The globally averaged surface temperature response to a doubling of the atmospheric CO 2 concentration was estimated, by examining the results of numerical models of the climate system. The WCP report concludes that C0i"induced climatic change is a major environmental issue but that, because of existing uncertainties, the development of a management plan for control ~f CO 2 levels in the

22


atmosphere and for preventing detrimental impacts on society would be premature. It was felt that research to place decision-making with respect to CO 2 on a firm scientific basis merits high priority. The meeting further emphasised that the CO2 problem affects both developing and developed nations and nUs for a special partnership of effort. The report of the Carbon Dioxide Assessment Committee of the U.S. National Research Council gives a detailed assessment of the various aspects of the CO2 problem. The model used a range of paths and uncertainties for major economic, energy and carbon dioxide variables, which allowed a 'best guess' of the future path of carbon dioxide emissions and a reasonable range of possible outcomes given present knowledge. The estimate of the net emissions of CO 2 from the biota was made on the basis of information presented in the report and available in the scientific literature. The possible future atmospheric CO2 concentrations were calculated using an estimate of 0.60 ± 0.10 as the likely future airborne fraction of the projected emissions due to fossil fuel combustion. The effects of CO2-induced climatic changes on agricultural, social and economic system were also assessed with emphasis on the United States. It was concluded that the longer-term agricultural effects are uncertain and depend strongly on the outcome of future research, development, and new technology in agriculture. The CDAC report reached a general conclusion similar to that of the WCP report, Le. that the evidence at hand about CO2-induced climatic change does not support steps to change current fuel-use patterns away from fossil fuels, although such steps may be necessary or desirable at some time in the future. The report pointed out that steps to control climatic change should start possibly with reductions of the emissions of other greenhouse gases,


23

since their control may be more easily achieved. Further, the CDAC report suggested that the CO2 problem might serve as a stimulus for increasingly effective cooperative treatment of world issues. The study of the US Environmental Protection Agency, EPA took a different approach to the problem by examining whether specific policies aimed at limiting the use of fossil fuels would prove effective in delaying temperature increases over the next 120 years. The projections of future energy demand and supply were made using the world energy model of the Institute for Energy Analysis. A global carbon model developed at Oak Ridge National Laboratory (ORNL) was used to estimate the atmospheric CO2 concentration. The changes of the atmospheric temperature were evaluated using a simplification of a one-dimensional radiative-convective model developed at the Goddard Institute for Space Studies. The EPA analysis concluded that only a ban on coal use instituted before 2000 would effectively slow down the rate of a global temperature change and delay a 2°C increase until 2055. It was concluded further that major uncertainties include the increasing concentrations of other greenhouse gases and the atmospheric temperature response and that alternative energy futures produced only minor shifts in the calculated date of a 2°C warming. Although the results suggested that bans on coal and shale oil are most effective in reducing temperature increases in 2100, the EPA study concluded that a ban on coal is probably economically and politically infeasible. A Committee of the Health Council of the Netherlands made an assessment of the CO2 problem in 1983. The energy scenarios upon which the assessment was based were taken from the IIASA study, with CO2 emissions

24


from fossil fuels in 2030 ranging between 8.9 GtC/year and 16.2 GtC/year. The changes in the atmospheric carbon dioxide concentration were calculated using a model of the carbon cycle. The concentration in 2030 was estimated to be 431 ppmv and 482 ppmv for the IIASA 'low' and 'high' scenarios respectively. Considerable emissions from the further exploitation of the terrestrial ecosystems were assumed but also more effective uptake by undisturbed forest systems and by soils due to charcoal formation in the process of burning during deforestation. The likely future temperature 500 pm) are taken at each station, according to a sampling protocol that takes into account the different types of flexible net (diameter = 500 nun), using: retractable panels, removable base (1/20 m 2), sampler "Surber" position, rack, metal frame, cutting blade, sampler "Shrimpnet" p0sition, and habitats defined by the support structure and the flow speed. A representative sample consists of eight samplings. The sorting and identification of the sampled taxons are performed to determine the taxonomic variety of the sample and its fauna indicator group. The habitats located in calm water (lentic facies) are prospected with the help of a shrimper, using traction over 50 em, or, by default, by back-and-forth movement over an equivalent surface (the additional surface compared with that of the Surber compensates for the loss of a portion of the individuals). A ring-shaped illumination lens is used for the sorting in a binocular lens (stereoscopic microscope G £ 50) issued for the identification of the taxons.


185

SAMPLING

The !BGN is determined per station, which is defined as the segment of a water stream whose length is virtually equal to 10 times the width of the stream bed at the time of the sampling. The detection of disturbance is facilitated in extreme situations at the moment of low waters (minimum flow, maximum temperature) or during critical periods (discharges and seasonal human activities). The samples must be taken during a period of stabilised flow for at least 10 days. For each station, the benthic fauna sample consists of eight samplings of 1/20 m2 each (volume sampled for the loose substrates: 0.5-1 L) performed separately in eight different habitats selected from among the combinations defined for each station. The eight samples together must provi!ie a representative picture of the mosaic of habitats of the station. Each habitat is characterised by a support-speed set. In the absence of certain habitats, the samples can be obtained according to the strata. Each stratum, sampled separately, constitutes a complete sampling. For example, in the absence of a len tic habitat in a mountain stream, the surface of the grid is sampled; then, separately, the inside surface and the underlying substrate are sampled a second time. The samples are taken wIth the help of the sampling devices. Each sample is immediately fixed on site by the addition of a 10 percent (v Iv) formaldehyde solution, placed in a plastic bag, transported packed in ice, and then stored in the refrigerator. The surface speeds are estimated for each habitat. The support categories (5) are studied in the order of the succession (from 9-0). For each support category, the sampling is made in the speed class where the support is best represented. The speed classes (5 to 1) are listed in decreasing order.

Simulatiolls of the Effects of Climate Change

186

When a monotonous station (straightened course, silted bed, or canal) does not include the eight different types of support, the number of samplings is extended to eight through samplings taken of the dominant support. The percentage of coverage of each habitat (SV set) can be estimated from the following: % r =

>75%

class =

5

50% 4

25%

10

>10

3

2

1

BIOLOGICAL ANALYSIS

Selected Taxonomic Unit

The selected taxonomic unit is the family with the exception of some fauna groups (branches or classes) with little representation or where the taxonomic analysis unveiled specialisations. The repertory includes 138 taxons which may be included in the overall variety (L t), of which 38 are indicator taxons that form the nine indicator fauna groups. The Mollusks and the Achetes are also listed. The collected organisms are sorted and determined according to larval, nymph or adult stage, provided that this latter stage is aquatic. Empty sheaths or shells are not taken into account. To facilitate the interpretation of the results, the samplings should not be mixed and the fauna list of the station should be prepared by indicating the distribution of the taxons in the eight habitats. Global Biological Index (IBGN)

The following must be determined sequentially: The taxonomic variety of the sample (L t), equal to the total number vf taxons collected even if they are represented only by a single individual.

187

Assessme1lt of Freshwater Quality

Indicator fauna class (GI) considering only the indicator taxa represented in the samples by at least three individuals or 10 individuals depending on the taxons. !BGN can be derived from the at and GI values. For example: GI

= 8, L t = 33 »>

IBGN

= 17

GI

= 5, L t = 30 »>

IBGN

= 13

L t = 14 »> IBGN = 7

GI =3,

Because of the significant absence of indicator taxa (3 or 10 individuals), the IBGN score equals O. Test Report

For each station, the test report must include the date; the exact geographic location (Lambert coordinates); the ecological type, if known; the distance from the source; the altitude; the length of the wet bed at the time of the sampling; the water temperature; the nature of the support and the flow rate pertaining to the eight samplings performed for the station (SV set) with an indication of the dominant habitat or, preferably, the approximate collected classes; the list of sampled taxons with their distribution over the eight habitats, with a possible indication of their relative abundance; the taxonomic variety of the sample t); the indicator fauna group (sequence number of GI); and the standardised global biological index (IBGN). For cartographic representation of the results, each segment of the stream can be assigned one of the following colours, depending on the value of IBGN:

0:

IBGN

~

17

16-13

12-9

8-5

~4

colour

blue

green

yellow

orange

red

188

Simulations of the Effect.; of Climate Change

The IBG variations throughout a segment or a water stream in its entirety can be plotted in a graph where the distance from the source is the abscissa and the index values are the ordinate. Example

An illustration has been prepared by the author of the Pont de Fleurey on the Dessoubre stream (affluent of the Doubs) at Jura Massif in France. The Dessoubre, a mesorhithron stream with the association Tadpole-TroutGrayling-Minnow-Loach, presEi!nts a habitat diversity and a water quality corresponding to its ecology type. The start of a trend manifested by the most stenoecious fauna to leave the habitats of the lenitic facies should be noted. In 1981, this station was one of the stations used for the sampling of the range of index values in search of optimal values. BIOLOGICAL QUALITY OF LAKES

Basis

Although benthic macrofauna, because of its variety and abundance, constituted the material of choice for the establishment of practical biological methods for the assessment of the general status of streams, at present no similar methods can be applied to still-water systems, although Limnology emerged with lacustrine investigations. This can be explained by several factors. The Character of the Organisms

Whereas benthos constitutes the core of the organism of streams, lakes are, however, characterised by microscopic planktonic organisms (phytoplankton and zooplankton) that have very brief developmental cycles, and present significant spatial and time-related variations. Thus, this

Assessment of Freshwater QualIty

189

material is difficult to use to determine the significance to the entire system. Therefore, employment of the zoomacrobenthos, whose integration power is much greater, has been projected. However, a portion of the species only colonizes in the littoral zones whose habitat mosaics prove to be very different from one lacustrine basin to the next. Brinkhurst shows the general phenomenon of a decrease in fauna (here, generic) variety with depth. The main components of the macrobenthos capable of colonizing lacustrine sediments up to depths of 250300 m belong to the "difficult groups," such as Mollusks, more specifically Pisidies, the Oligochetes, and especially the Chironomide dipters for which the analysis of a great number of species associations has offered for a long time the basis for lacustrine biotypology with the work of the great forerunners such as Thienemann or Brundin in the late 1940s. The studies of comparative biocenotics, performed with this material, can be conducted only by true specialists, which unfortunately is increasingly less the case. Interpretation Ambiguities (Simplified Methods)

While simplified methods are proposed based on the single phytoplankton or on the basis of the species of a single faunistic class, order, or family, the challenge is in uncovering the meaning of the analytical findings, especially when a global qualitative perspective requires considerable integration of widely diverse information. Therefore, the indices proposed by Lafont et al. by a simplified analysis of the Oligochete populations objectively express the biological quality of the watersediment interface; Saether considers the communities of Chironomide dipters of the deep zone to be the indicators of the "quality of the waters," and links his results to a

190


"trophic level" relative to the system, pollutions, and dysfunctions that are included and not differentiated. The application of this method to the lakes of the Jura approximates "eutrophic" effects; the phytoplanktonic biomasses mark a varied range of partial primary productions, and physicochemical analyses of the sediment reveal a great variety of sedimentological types. Yet, equally apparent is the absence of relationships between the global sedimentary composition (% carbonates and MO), the primary production, and the depths of the basins. Two main conclusions can be drawn from these comparisons: The need to differentiate the trophic level from the nutritive substance content which express a potential and the "trophic status" of a system, by expressing a functioning or dysfunctioning mode whose sediments and fauna supply images for which interpretations must be found. The usefulness to have available a practical biological method for the assessment of the general biogenic aptitude of a lake, which would offer sufficient synthetic significance. Besides the recent proposals of Lafont et al. and Mouthon which propose, respectively, simple assessment methods for the biological quality of lacustine systems on the basis of Oligochetes and Mollusks, all other proposals tend to define different "trophic levels," but not the resulting biogenic aptitudes. Estimate the Biogenic Qualify of Lakes

An experimental classification of lacustrine systems based on a comparative analysis of the benthic fauna has been proposed. This method is called the Lacustrine Biogenic


191

Index, and includes a comparative sampling protocol, original biologic descriptors, and a standard table that allows the definition of the biological type and the biogenic index of a lake. Only fine sediment over 5 cm is collected using a modified Ekman bucket with the addition of lateral ballast as well as a penetration limiter. Coarse substrates and hydrophytes are avoided, as are certain sites such as beaches, harbours or substrate enclosures. Two samplings are performed each station to form a station sample; and two depths, to which two isobaths correspond, are prospected (Zo at 2-2.5 m; and Zf at 3/4 Z maximum relative depth). The number of stations per isobath is proportional to the length of each isobath, and should be determined using the following factors:

= 1.8.JlOL

(1)

at Zf nf = 1.4 .JlOL

(2)

at Zo, no

where L is the length of the isobath in question, expressed in km. The stations are distributed regularly (virtually in an equidistant manner) over each isobath. The samples are taken during a single sampling trip during an isothermia period which follows thawing and springtime circulation. Depending on the altitude, in the Jura lakes the expeditions took place in April or in May. Each sample (consisting of two samplings) is filtered through a conic net with a mesh width of 250 11m; then 5 percent formaldehyde solution is added and the sample is then placed in a plastic bag with the air removed. The samples are transported on ice, and stored in a refrigerator. The samples are analysed separately. The


192

macroinvertebrates are identified but not counted out. The selected taxonomic unit is genus except for the Oligochetes, Nematodes, Hydracarians, and Ceratopogonidae. A listing shows the fauna data and the frequency of each taxon is expressed in percentage of occurrence in relation to the no and nf counts of the stations (or the samples per isobath). The quality coefficient of the fauna of the fine sediment is determined where the found taxa are classified in the decreasing order of sensitivity to the physicochemical quality of the water-sediment interface. Only taxon indicators are selected whose frequency is at least equal to 50 percent of the number of samples no taken at depth Zoo The descriptors include: va = fauna variety ( generic) at depth Zo, qo = quality of the fauna at depth Zo, and df = bathymetric distribution coefficient at depth Zf

vj

dj=kva

(3)

where k = 0.047 vo + 1, F = relative faunistic deficit index, and F = ?df. qo. For example, if vo = 38 and F = 0.77 for type B4, then biogenic index/20 = 15; and if vo = 23 and F = 0.38 for type B~ then biogenic index/20 = 08. Qualitative levels include eubioric lake, eumerobiotic lake, merobiotic lake, merodysbiotic lake, and dysbiotic lake; and the quantitative levels include oligobiotic lake, oligomesobiotic lake, mesobiotic lake, mesopolybiotic lake, and polybiotic lake. The combinations of the two series of information is used to define the type of lake as either euoligobiotic or mesomerobiotic or dyspolybiotic lake. The variety of endobenthic fauna sampled in the littoral zone beyond the river zone (Zo = -2, -2.5 m) constitutes a good indication of the biogenic potential of the system in relation to consumer organisms.

10 Ecological Risk Assessment The ecosystem health metric proposed is a comprehensive, multiscale, dynamic, hierarchical measure of system resilience, organisation, and vigour that closely tracks the concept of sustainability. Assessment scale is an important issue, because it tends to define the scope of the policy options considered for mitigation. Currently, an overemphasis exists on population and process-level analyses at the expense of the ecosystem and ecoregion levels. As with the health metric proposed, assessment of ecosystems at multiple levels is important to insure that the cure is no worse than the disease. Finally, a somewhat different perspective to assess ecological systems is discussed. By considering changes in an ecosystem's delivery of ecological benefits (goods and services), the assessment may be able to answer more directly the question of significance. ECOSYSTEM HEALTH

The term "health" is commonly used in reference to ecosystems by both scientific and policy documents, but a satisfactory definition of ecosystem health remains to be developed. While the framework of human health may

194


provide a starting point, severe limitations are imposed on the parallel between human health and ecological health. In addition to its use in ecological assessments, a definition of ecosystem health also provides a means to aid the integration of the analyses of ecological and economic systems. As a starting point, this analysis begins with five axioms of ecological management: The Axiom of Dynamism. Nature is more profoundly a set of processes than a collection of objects; all is in flux. Ecosystems develop and age over time. The Axiom of Relatedness. All processes are related to all other processes. The Axiom of Hierarchy. Processes are not related equally, but unfold in systems within systems, which mainly differ regarding the temporal and spatial scale on which they are organised. The Axiom of Autopoiesis. The autonomous processes of nature are creative, and represent the basis for all biologically-based productivity. The vehicle of that creativity is energy flowing through systems that in turn find stable contexts in larger systems, that provide sufficient stability to allow self-organisation within them through repetition and duplication. The Axiom of Differential Fragility. Ecological systems, which form the context of all human activities, vary in the extent to which they can absorb and equilibrate human-caused disruptions in their autonomous processes. These axioms regularly recur, even if implicitly, in the following discussion, and they are essential elements of the definition of ecosystem health proposed below.

Ecological Risk Assessment

195

Ecosystem health is often framed in terms of human health. While both are complex systems, medical science has a large body of knowledge and expert systems (in the form of doctors) available to advance diagnosis. Such analytical tools are absent for ecosystems. However, ecosystems have been studied extensively with respect to their stability and resilience. Six major concepts are most often used to describe ecosystem health : homeostasis, the absence of disease, diversity or complexity, stability or resilience, vigour or scope for growth, and 'balance between system components. Each concept represents a piece of the puzzle, but none is sufficiently comprehensive, especially in terms of being able to deal with many different levels of ecological systems. Homeostasis is the simplest and most popular definition of system health: any and all changes in the system represent a decrease in health. The greatest difficulty with this approach is in differentiating between naturally occurring stresses and .external (including anthropogenic) stresses. This definition is best used for warm-blooded vertebrates, since they are homeostatic and since normal ranges can be more easily determined from large populations. However, for ecological systems, all changes (or even any given change) cannot be assumed to be bad. The best exampl\f this is succession*for the initial state,

196


succession is an irr~versible change, and one that might be necessary for the system to be sustained. Given that ecosystems are constantly changing, this definition does not deal with a fundamental characteristic of ecosystems. The definition of ecosystem health as the absence of disease has several failings. First, while various (including anthropogenic) ecosystem stresses can be described, their mere existence does not indicate that they are adverse stresses. A separate, independent definition of ecosystem health would be required. Second, this definition yields only a dichotomous result that is inadequate to characterise complex systems. The notion of basing a definition of ecosystem health on a system's diversity or complexity rests on the assumption that these characteristics are predictors of stability or resilience and that these are indicators of ecosystem health. Presently, the analytical basis is insufficient to use this concept, but network analysis may yield a more sophisticated framework for incorporating system diversity into a definition of ecosystem health. Stability and resilience are key measures of ecosystem health, since healthy organisms and systems have the ability to recover from stresses or to use the stress in some creative manner to improve their status. A failing is that these measures do not characterise the level of system organisation or the level at which the system is functioning. Odum has suggested that the level of a system's metabolism (energy flow) is an indicator of its ability to deal with stresses. The concept of ecosystem balance is based in Eastern traditional medicine, and the notion that a healthy system is one that maintains a proper balance between its parts. However, the proper balance can only

Ecological Risk Assessmerzt

197

be determined by some independent measure of ecosystem health.

Based on these framing concepts, a practical definition of ecosystem health must have four essential characteristics. First, it must integrate the definitions described above into one that combines system resilience, balance, organisation (diversity), and vigour (metabolism). Second, it must represent a comprehensive description of the ecosystem. Third, it must use weighting factors to compare and aggregate different components of the system. Finally, it must be temporally and spatially hierarchical. Such a definition would be: "An ecological system is healthy and free from distress syndrome, if it is stable and sustainable-that is, if it is active, and maintains its organisation and autonomy over time, and is resilient to stress". Accordingly, a diseased system is one that is not sustainable, and will eventually cease to exist-clearly illustrating the importance of the temporal and spatial aspects of the definition. Distress syndrome refers to the irreversible processes of system breakdown leading to death. Two very important tools for making operational this definition are network analysis and simulation modelling. Network analysis, in this context, refers to all variations of the analysis of ecological and economic networks. It has the potential for yielding an integrated, quantitative, hierarchical treatment of all complex systems, including ecosystems and combined ecological-economic systems. An important area of network analysis is the development of common pricing mechanisms for ecological and economic systems. In complex systems with many interdepen-dencies, a problem with mixed units is often present. Ecological analyses have ignored this

198


problem by choosing a single commodity as an index; yet this ignores interactions between commodities, and is consequently unrealistic and quite limiting. Evaluating the health of complex systems demands a pluralistic approach and an ability to integrate and synthesise the many diverse perspectives that may be present. An integrated, multiscale, transdisciplinary, and pluralistic approach is required to quantitatively model systems (including organisms, ecosystems, and ecologicaleconomic systems). Achieving such a capability requires the ability to predict the dynamics of ecosystems under stress as well as advances in high-performance computing. ECOLOGICAL ASSESSMENT OF REGIONAL SCALE

Assessment of scale is important, because scale tends to define the scope of the policy options considered for mitigation. Currently, an overemphasis exists on population and process-level analyses at the expense of the ecosystem and ecoregion levels. As with the health metric proposed above, assessment of ecosystems will be important at multiple levels to insure that policy decisions do not result in undesired ecological consequences. Also, guarding against haphazard aggregation of measures across ecological levels of organisation will be important. Different scales of ecological systems may be driven by very different dynamics so the best indicators or metrics for one level may be inadequate or misleading at another scale. While the concept of multiscale analyses is logical and desirable, it poses significant difficulties since most ecological research deals with very small geographic areas (usually 1 m 2). Recognising the need for ecological assessments to deal with much larger landscapes, some


199

ecologists began in the 1980s to argue, that regional-level ecology was important to understand the smaller scale and that ecological assessments must be capable of assessing at the regional level. "Ecological risk assessment, unlike human health risk assessment, must address a diverse set of ecological systems, from tropical to Arctic environments, deserts to lakes, and estuaries to alpine systems.... Ecological risk assessment may occur over much wider temporal and spatial scales than those for human health risk assessment". Meeting this need for multiscale analysis will require the same type of research required to provide the foundation for the definition of ecosystem health, namely, network analysis and simulation modelling. Analyses such as these will be much more feasible because of recent advances in high-powered computing and visualisation techniques. An important element of multi scale analysis of ecosystems, and even single scale analyses, is the proper characterisation of uncertainty. Even with the significant advances in modelling, large amounts of uncertainty will exist with respect to anthropocentric effects on ecosystems. Developing the means and the methods to characterise this uncertainty in a meaningful manner for policy makers should be a major research area for ecological assessment. Ecological Benefits Patterns

Even when unable to assess ecological health across scales, space, and time, some often-asked issues remain, such as the significance of the findings. Even if public policy advances were at the point where the maintenance of ecological health is considered an important goal, tradeoffs and choices will be needed by policy makers. This situation strongly suggests that simply characterising the

200


risk of potential outcomes will be an inadequate response. By developing the ability to characterise ecological benefits more completely and by characterising the impact from the loss of ecosystem health on the delivery of those benefits, ecological assessments will make great strides towards resolving the signifi:ance matter. Current ecological assessment documents and frameworks clearly state that policy makers must be consulted to develop the ecological risk assessment endpoints and that the assessment must ascertain the significance of observed changes. The selection of assessment endpoints relates in part to policy interests (e.g., to specified regulatory endpoints or to public concerns); thus, changes in assessment endpoints must be related ultimately to changes in parameters of the ecosystem that humans care about (anticipating the significance issue) . The products that will result from the process clearly will not be couched in terms with which policy makers are most comfortable nor in the metrics that they will understand and be able to communicate to their various constituencies. This tendency to describe scientific findings in terms that are, in the view of the policy- maker, either arcane or in multiple metrics has been referred to as multidimensionality. The result is that the findings are described in a manner so detailed and fragmented that no one can grasp the overall implications. Benefits are ecological goods and services, and have been compared to ecological structure and function. Ecological goods and services can be described as those benefits that humans derive from ecological systems. For example, cut trees provide lumber (an economic and ecological good), while uncut trees take up air pollutants (an economic and ecological service). The uptake benefit


201

will be lost when the trees are cut for lumber, and vice versa. To economists, the term "benefits" often denotes a monetised valuation of an economic good or service. However, in this context, the term "benefit" is used to refer to all ecological goods and services whether or not their value has been monetised. Since the monetisation step is often controversial, leaving it aside permits these efforts to focus on the scientific questions surrounding the identification and quantification of benefits. However, an analytical loss will exist in the absence of monetising (a common metric with which to measure and express the magnitude of the benefits). Ecological benefits occur in four groups: (1) market benefits (first wave), such as lumber, for which economic markets exist; (2) non-market use benefits (second wave), such as recreational benefits, for which no direct markets exist; (3) non-market, non-use benefits (third wave), such as the existence value and bequest value; and (4) fourth wave benefits are those that would fit into any of the three previous categories, but which have not routinely included in previous benefits analyses, such as pollution uptake, climate modification, habitat, and biodiversity. While a variety of graphical methods can depict the status and change in magnitude of these benefits, a polartype chart may be best to demonstrate the technique. The polar chart has some appeal, because of its division into four quadrants.

202


By placing first wave benefits in quadrant one, second wave benefits in quadrant two, etc., the status of each wave's benefits can be clearly shown. This graphical analysis might illuminate a policy maker's choices; for instance, consider the choice to harvest the trees in a hypothetical old-growth forest.

11 Environmental Monitoring The atmosphere has few mixing constraints and, therefore, this can be achieved by measurements in remote areas and in the upper atmosphere. Carbon dioxide. Historical trend of atmospheric carbon dioxide as well as estimates of future concentrations are based primarily on a sole set of continuous observations, which dates only from 1958. Additional and continuing baseline data are necessary to determine the global representativeness of the current trend, to verify the future estimates and to study the partitioning of CO2 between the atmosphere, oceans and biosphere. Aerosols and particles. Aerosols and particles in the

atmosphere play a special role in the atmospheric energy balance and in physical processes important in the fonnation of clouds, precipitation, fogs, etc. Moreover their role depends not only on the total particle count but also on the number of particles of various sizes and their distribution with height. The rapid development of vertically directed LIDAR as a measurement technique gives promise of an early capability for monitoring the vertical distribution of particle loadings well into the stratosphere. This technique should be utilised as soon as feasible to complement or perhaps replace periodic aircraft

204


sampling. By monitoring the intensity of solar radiation at selected narrow-bands in the visible and ultra-violet spectral regions (e.g., 0,50 and 0,38 micrometers), direct information can be obtained on the total atmospheric loading of aerosols (atmospheric turbidity) in the optically effective size range.

Solar radiation. Since solar radiation is the critical energy source to the earth and atmosphere, comprehensive monitoring is required for trends in the solar energy received at the surface. Instruments for the following measurements are commercially available and are used in operational programmes: Broad-band direct and diffuse radiation (e.g., measurements of all wavelengths>0.40, >0.53, and >0.70 micrometers) Narrow-band direct radiation (e.g., measurements between the wavelengths of 0.30 to 0.35, 0.35 to 0040, ... 0.55 to 0.60, 0.60 to 0.70, 0.70 to 1.00 and 1.00 to 1.80 micrometers) Net (incident minus reflected) all-wave radiation. Meteorological data. Standard meteorological surface observations, induding wind, temperature, humidity, pressure, prevailing weather, etc., should also be obtained to complement the basic measurements. In addition, vertical observations of temperature, humidity, pressure and wind velocity by rawindsonde should be made.

The earth's surface. Various land-use practices that significantly alter the earth's surface such as deforestation and creation of man-made lakes, can affect local climate by influencing the energy balance. To determine whether large-scale changes have occurred, global land-use should be inventoried periodically, for example, every five years. Such a survey can best be carried out by satellite measurements.

Environmental Monitoring

205

Qoudiness and albedo. Since global climate is particularly sensitive to changes in cloudiness, surveys by satellite of this parameter should be encouraged even though there is no defmite indication that man has as yet caused wide-spread alterations in cloudiness. Measurements of stratospheric cloudiness and water vapour may have to be made from aircraft. Another particularly useful satellite"measurements is that of wholeearth albedo. Variations of the earth's reflectivity, which can be affected by land-use, cloudiness, etc., can be documented by such measurements. Waste heat. Because of the increasing rate of energy consumption throughout the world, the amount of waste heat produced by man could become a significant regional climatic factor in several decades. Therefore, energy-use statistics should be inventoried continuously on a regional basis to determine their current importance. Nitric oxide and ozone. Concentrations of these trace gases in the stratosphere may be affected by the operations of supersonic aircraft. Background concentrations of nitric oxide, a product of combustion, and ozone, a product of stratospheric gas reactions, should be determined before large scale supersonic flights begin. Recommend that the following variables be initially monitored at low exposure (baseline) stations: Atmospheric carbon dioxide content: atmospheric turbidity; solar radiation (including broad-band direct and diffuse radiation, narrow-band direct radiation, and net all-wave radiation); standard meteorological variables. Were commend that the following variables be considered for inclusion at a later date: Vertical distribution of aerosols; size aistribution of aerosols; rawindsonde data; surface vertical fluxes of carbon dioxide; global albedo (by satellite); ozone, water vapour and trace gases in the

206


stratosphere (by aircraft). The following variables be monitored at medium exposure (regional) stations: Atmospheric turbidity; solar radiation (including broadband direct and diffuse radiation and net all-wave radiation); standard meteorological data. DATA FROM AIR, WATER, SOILS AND BIOTA PERTINENT

Before considering in detail, the range of variables from air, water, soils and biota for possible inclusion in a monitoring system it is useful to stress the dynamic interrelation of these media via the geophysical, geochemical and biological transport mechanisms operating in the environment.' Effective analysis of any secular trends for potentially hazardous substance will be made much simpler. This involves a study of the sources and rates of injection of each substance into each environmental medium and the rate of removal into other media, i.e., residence times. The ultimate fate of each substance, whether it accumulates irreversibly in anyone medium or whether it continues to cycle indefinitely.

Air. Residence times of substances emitted to the lower atmosphere are generally short (weeks or less) unless they enter the stratosphere where they can remain for many months or years. The atmosphere is thus more appropriately regarded as a transport mechanism with rapid and efficient mixing, making it possible to obtain accurate representative measurements of atmospheric constituents by sampling at a few selected points only. When monitoring the quantities of the different substances it is necessary to take into consiqeration whether the substance occurs as a gas, as particles or attached to particles. The actual size distribution of particles is very important when considering their availability to organisms, including man. .


207

From the budgeting point of view it is important to monitor injections of substances to the air and the transfer mechanisms from the air to water and soil. The interfaces between atmosphere and water and between the atmosphere and the continents deserve particular attention. Of special significance among the transfer mechanisms is precipitation since it has an important scrubbing action on atmospheric gases and particles. Its composition (precipitation chemistry) is a useful guide to the nature and amount of airborne substances carried to the earth's surface and available to interact with biota. Water. Residence times in water are longer than those of air and the presence of serious mixing constraints in oceans makes representative sampling much more difficult unless many more sites are involved. Despite this qualification, bodies of salt and freshwater reflect the history of surrounding land use in an informative way. Substances released into rivers etc. find their way into aquatic biota and bottom sediments which may often irreversibly accumulate many substances and thus act as a valuable historical record of previous changes and trends. The output from rivers to the oceans is not only a national and regional problem but also of concern to any global budgeting of critical substances essential for the global monitoring system. Soils. Soils like sediments are often the ultimate sinks of many important substances particularly in low rainfall areas. They are the most intensively used resource of any nation and the irreversible accumulation of substances in them is thus of critical importance. Mixing constraints are of course greater in soils than in air or water and there are large-scale geographical differences in the accumulation and loss of substances to soils, depending on local usage by man, soil chemistry, rainfall etc.

208


They not only receive substances by dry deposition and precipitation from the air but are the source of dusts and gaseous exhalations which can be atmospherically transported over great distances. Volatile substances such as organochlorine compounds and dimethyl mercury are of interest in that they may evaporate from warmer soils and condense in soils of cooler regions. Special attention should be paid to the occurence of new technical substances in the soils of tropical regions.

Biota. The reason for monitoring certain substances in biota is twofold. They may cause adverse biological

effects and they may be in greater concentrations and therefore more readily detectable. Knowledge about the levels found may be used in risk evaluation. For substances with threshold-effects the existing levels should be used for an estimate of the safety margin before effects appear. Organisms are important as a means of transport for substances through the biosphere. They can take up and accumulate certain chemicals and transmit them through food chains, by a process of biological magnification, where an increased accumulation at higher trophic levels occurs. Therefore the effects are often most pronounced at the tops of the food chains. The transport of substances along food chains takes time and it is thus of great importance to detect any significant accumulation of substances at the lowest trophic levels. By using sophisticated chemical methods it is now possible to detect even very minute amounts of substances. Organisms at the bottom of the food chains contribute to an early warning system. Even similar substances may behave differently in the same food chain. This depends on different metabolic patterns and abilities to excrete substances. This variability


209

has a marked genetic component and is partly the explanation of the development of tolerance. In aquatic organisms, the direct uptake of substances from water may sometimes be more important than via the food chains. When chemical methods are not sufficiently sensitive to estimate the trace amounts of a substance in the abiotic environment, accumulator organisms may be analysed instead. Bioaccumulators also often integrate the chemical environment both in time and space. A fish in a lake may integrate the conditions in that lake over a long period of time and wide ranging marine organisms may reflect the situation in extensive marine areas. In certain cases specific organs may give additional information on the chemical situation in the environment. For example, different amounts of mercury accumulating In the feathers of migratory birds formed at their summer and winter quarters respectively, indicate geographical differences in mercury exposure.

In certain cases organisms may be used as indicators of the presence or absence of a specific substance or of certain levels of it in the environment. The foregoing discussion emphasizes the need to sample and measure environmental substances in such way in all media that their flux rates can be calculated and an "environmental balance sheet" drawn up for each substance. This will help us to gather valuable information such as, for example, whether a detected increase of a substance in one medium represents a real overall global increase or merely the appearance of the substance working its way through the environmental cycles from another medium." Since ,nearly all scientific competence in investigating the environment is traditionally media oriented, it is unrealistic to erect a completely new system based on this

•

210


dynamic approach. It is thus proposed to discuss below the range of monitorable parameters in each of the media separately and to attempt a synthesis at the end which once more emphasizes the need for a dynamic overview of the whole environment. Atmosphere

Carbon dioxide. Land plants obtain all their carbon from atmospheric carbon dioxide and from carbon dioxide released from soil respiration. All animals, including man, exist from the carbon compounds made by plants. Changes in the amount of atmospheric carbon dioxide might have an influence on global climate as previously indicated or may alter primary productivity in green plants since carbon dioxide is sometimes a limiting factor to plant growth. Sulphur dioxide and hydrogen sulphide. Numerous epidemiological studies clearly indicate an association between sulphurdioxide and health effects of varying severity. Other studies have shown that chronic injury to plants can occur with prolonged low concentrations of these gases as well as adverse economic and aesthetic phenomena related to atmospheric visibility, and the soiling, and corrosion of materials. Carbon monoxide. This gasis known to have important physiological effects on man at the increased levels found in dense traffic. It is now known that the surface of the oceans releases substantial amounts into the atmosphere. However, its fate in the atmosphere is not known and it is of some importance to as certain whether the gasis accumulating there. Nitrogen oxide and nitrogen dioxide. These gases play important roles in the formation of "photochemical smog" which is being recognised as an increasing problem to man


211

and plants in and about urban complexes in the temperate zone. When released into the lower stratosphere by high flying aircraft, these gases possibly may interfere with the ozone balance.

Ozone (and ozone precursors). These substances have an important chronic and acute impact on biological systems by the impairment of performance, on pulmQnary function, and by vegetation damage. Ammonia. Almost all of the ammonia in the atmosphere is produced by natural biological processes although considerable increases are found over industrial cities. The ambient air concentrations are lower than those hazardous to plants and animals. However, a long-term trend would have an important biological significance. Aerosols and particulates. The impact of these substances on biological systems covers a wide range of important physical and pathological consequences, both direct and indirect. For instance, Aitken Nuclei of less than O.IJl radius are important in the formation of precipitation, fogs, and haze, etc. The so-called "large" particles in the 0.1-2 Jl range affect optical phenomena such as visibility and turbidity and can be important lung irritants in man, especially the particulate decay products of sulphur oxides, which can carry absorbed or adsorbed gases deep into the respiratory system. Insecticides, herbicides and other biotoxins (in air and precipitation). The bio-environmental problems associated with the use of insecticides and herbicides and a number of other biotoxins, particularly those from industrial processes, fuel and refuse burning have been well documented. Since one of the most rapid and effective methods for distribution of these materials on a global basis is via the atmosphere, early detection of significant changes in their distribution could be achieved by

212

Simulations of the Effects of Climate CMnge

monitoring the concentrations of these materials in air and precipitation.

Chlorinated aliphatic hydrocarbons. Carbon tetrachloride, trichlorethylene and similar compounds used in cleaning may become important atmospheric constituents in the future. Water

Although the organisational pattern required for monitoring freshwater is likely to differ substantially from marine monitoring, many of the critical variables to be studied are the same in both media. The following discussion, dealing principally with the marine environment, also applies to freshwater unless otherwise stated. There are two major groups of parameters of potential importance in water monitoring. Biological stimulants. Biological toxins including radionuclides.

Biological stimulants. The effects of biostimulants on the environment are usually observed on a local scale and may result in unsightlyblooms of aquatic vegetation, algae and bacteria. Unless these products are removed from the system and allowed to decay elsewhere~ premature deoxygenation of the aquatic environment can occur. Chemical species known to stimulate the growth of primary and heterotrophic producers include N0'3,NH3,PO;-,K+, CO;-,HC03 and organic matter, along with various trace metals. Other substances regarded as biostimulants are a variety of organic compounds such as vitamins, hormones and other unidentified "growth factors" present usually in trace amounts, particularly in domestic sewage.


213

In coastal areas, estuaries, fjords, lagoons and epicontinental seas, the increasing input of nutrients and potential nutrients from sewage and industrial outlets as well as from dumping is often the cause of a disturbance in the normal biological equilibrium. Because of sampling and storage problems, it seems inadvisable at present to split up the different phosphorus and nitrogen containing nutrients into subgroups. However, total phosphorus and total nitrogen (excluding gaseous nitrogen) both in dissolved and particulate form should be included in a monitoring system for the seas. This restriction to total P and total N may be less satisfactory for freshwater. Because of the anticipated effects that a rise in the carbon dioxide content of the atmosphere might have on climate, it is necessary to understand the circulation of carbon dioxide not only in the atmosphere but also in the oceans, and especially the exchange of carbon dioxide between sea-surface and atmosphere. It is expected that an increasing amount of information about carbon dioxide in the sea and components of the carbonate system will be achieved by ongoing research and survey activities within the next five years. This will be accomplished through improved methods and instrumentation. Continental erosion, industrial activities, sewage injection and dumping of mass residues from chemical production e.g. red mud, nutrification and overproduction might change the turbidity of surface waters considerably. Such events might also effect offshore areas all over the world and become an international problem, especially when the dumping of large quantities of relevant material is carried out in off shore waters. Unusual depletion of oxygen normally indicates high organic loading of water. This is certainly not a world wide issue, but may be a regional problem, especially in such areas where natural processes and man-included

214

Simulatiolls of the Effects of Climnte Challge

effects both lead to stagnation and emphasize an already existing natural tendency of oxygen deficiency as is the case in the Baltic. It is therefore desirable to include oxygen measurements in a monitoring system. Biological toxins. Potential toxins include almost all heavy metals and many organic compounds. Toxicity may manifest itself at any level of the food chain or may significantly alter the species composition of biota by enhancing those populations of organisms differentially tolerant of the specific toxin involved. In other cases, where substances are not directly toxic, they may concentrate in tissues of living organisms making them unfit for consumption by other organisms, including man. Such materials, if they are persistent in the environment, can increase in concentration in aquatic systems.

Many metals, including mercury, lead, cadmium, vanadium, chromium, copper, zinc, iron, arsenic and selenium and their related inorganic and organic compounds are considered to be potentially hazardous. The levels of mercury and lead are believed to have risen considerably in the surface layer of the oceans through man's production and use of them. Both have regional if not global effects on the marine ecosystem and are accumulated in food chains. The other metals mentioned here are mostly of local or regional interest only. Chlorinated organic compounds such as DDT and its metabolites, Aldrin, Dieldrin, Endrin, residues from the fabrication of polyvinyl chloride and similar chlorination products, i.e., aliphatic, chlorinated hydrocarbons, polychlorinated biphenyls, and residues from the fabrication of such compounds, alicyclic chlorinated compounds such as Lindane (' g- BHC) are considered to be potentially hazardous.


215

The toxicity of various oils and oil-products varies widely depending on the combination of environmental factors and also on the biological state of the organisms at the time of contamination. Different species and different life stages of organisms have been demonstrated to show different susceptibilities to pollution. Natural biogenic hydrocarbons on the other hand may have well defined biological functions. Therefore methods for oil pollution monitoring must be able to deal with the entire spectrum of oils and oilproducts ai: high and low concentrations as well as with Hie natural hydrocarbons in sediments and organisms. Further, for pollution research and for law enforcement there is a need for differentiation between natural hydrocarbons and pollutants and for the recognition of oils form different sources and among oil-products resulting from different refining processes. Existing analytical technology, using gas-liquid chromatography is well on the way to achieving this. Many organic compounds, which occur naturally or are emitted by human activity, may influence biota indirectly through their capacity to complex with or in other ways modify the chemistry of inorganic ions. These processes may alter the biological availability not only of the toxic heavy metals but also of essential trace metals required for the normal growth of organisms. The full magnitude of such problems cannot be understood until the organic contaminants are identified and their chemical stability and affinity for metals assessed. For the present, wherever possible, metal analysis should differentiate between species in ionic solution and those in organic combination. The availability or toxicity of metal ions is also strongly dependent upon concentrations of accompanying ions, particularly hydrogen, calcium and magnesium.

216


Metal toxicity to fish is known to be reduced by factors of ten to a hundred in "hard" as against "soft" waters. Soil

Soil composition. A great deal is already known about the physico-chemical composition of the world's soils, largely as a result of the long-term painstaking surveys of surface geology and soil patterns necessary for mapping the potential mineral at:ld agricultural resources of a nation. These are essentially national or regional problems. A recent and more sophisticated development has been the use of stream sediment analysis. Streall'l, lake and marine sediments average the prevailing soil chemical conditions for trace elements over a wide area and their use as indicators is proving a valuable tool in studying the occurrence of mineral deficiencies. In future it may be possible to use this method for studying the regional buildup of aerially distributed pollutants which fall onto and accumulate in soils often thousands of kilometers from their source. The great value of the analysis of plant and animal tissues as indicators of prevailing soil conditions is already well understood. Non-ferrous (heavy) metals emitted to the air or directly deposited on soils can be fixed, particularly by soil organic matter. Many of the metals including lead, arsenic, antimony, nickel, indium, mercury, cadmium, zinc, cobalt and chromium are known or suspected to be a hazard to human and animal health, several having been linked with the occurrence of cardiovascular disease and gastric and other cancers. Mercury can be alkylated in certain soils to highly toxic forms by soil bacteria. DDT, PCB and other organochlorines may be fixed in certain soil horizons and also have significant effects on biota in soils. Any of these


217

contaminants may undergo a process of biological / concentration as they passup the human food chain. Studies of the dynamics of their accumulation, movement, and their residence times in soils are needed using soil, plant and animal analyses. Macronutrients (5, N, P and C compounds) constitute major factors of soil fertility. Problems may arise in connection with the wide and intensive use of fertilisers or improper land use. Soil structure and cover. Under intensive grazing and/ or mineral fertilising, soil structurE:" and the vegetational cover of soils often suffer a decline. This is normally a local problem but may be a matter of international concern where extensive deforestation or overgrazing, overburning or other human pressure leads to a loss of soil organic matter, to bare soil, to windblown soil and even perhaps to the extension of arid zones. This can be particularly serious where plant regeneration is very slow. The extension of bare ground can be registered by satellite sensing.

Organisms Organisms will collect and sometimes accumulate from air, water and their food, certain toxic substances and radionuclides. The coverage of the monitoring programme should include monitoring at the four main trophic levels: primary producers (green plants); primary consumers (herbivores); secondary consumers (predators); decomposers and scavengers. It also follows that particular attention must be paid

to those organisms that show high accumulation rates. These can be used as test organisms and temporal integrators. It should also be recognised that organisms that feed over a wide area can effectively integrate geographical variation in contamination levels.

218

Simulations of the Effects of Climate Change ANALYTICAL METHODS FOR DIFFERENT CRITICAL SUBSTANCES

The above general review of a wide range of variables needs to be followed by a discussion of groups of critical substances leading to a selection of the priority substances for the initial stage of the monitoring programme. Here taken note of the preliminary results of a special working party of SCOPE dealing with: "Materials which may significantly alter the biosphere and their determination and assessment". This working party will later report on analytical methods for different critical substances. The relevance and technical feasibility of monitoring the priority variables and are satisfied that they are appropriate to the problems, and can be monitored with available techniques. Special operational manuals have to be prepared at a later stage when the final decisions about variables have been made.

Pesticides and related substances. DDT and its metabolites and degradation products may serve as a valuable model for the monitoring of pesticides in general. Other persistent organochlorines are aldrin, dieldrin, BRC, endrin, methoxychlor, lindane and heptachlor. Some of these compounds are widely used, but it is not yet proved that they have the same general global distribution as DDT. Polychlorinated biphenyls (PCB) are very resistant to biodegradation, have a global distribution and marked effects on biota. They should be given high priority in any initial monitoring programme. Substituted phenoxy acetic acids (herbicides) and' organophosphorus compounds may be considered later for further inclusion in the global system. It has yet to be established whether these compounds have a global distribution. Non-ferrous (heavy) metals. Once liberated to the environment from mineral extraction and purification, these will always be a potential hazard as they are never


219

biodegradable. It is possible that they may eventually become immobilised as very stable substances in marine sediments but more information is needed on this. One particular difficulty is that unlike organochlorine compounds, metals already occur in the natural environment so the problem of arriving at natural levels is much more difficult. First priority should be given to lead, mercury and cadmium as these three metals are already significantly involved in environmental problems. Other metals such as arsenic, zinc, vanadium, selenium, berylium, nickel, chromium and manganese, may be included in the monitoring system at a later date. Organic substances in the oceans. The occurence of petroleum products in the oceans is regarded by some scientists as a very serious global problem. The compounds from crude oil may enter the oceans from oil spills; during the transport of oil products over the seas or, in the case of volatile fractions, through aerial transportation. The oil problem is important and possible global effects are foreseen. Pilot activities are given high priority.

The Chlorinated aliphatic hydrocarbons, waste products from the plastics industry, have been found to have an extensive distribution in the North Atlantic as a result of ocean dumping. Even if they are rather toxic, they are broken down within a comparatively short time. These substances do not have the same priority as PCB but may be considered for inclusion in a global system at a later date. Substances in relation to geochemical cycles. Human activities may change the geochemical cycles of the major macro nutrient elements at least in local areas. Much attention has been paid to the environmental problems relating to the sulphur cycle. As the man-made emissions of sulphur to the atmosphere have about the same size as the natural emission, it is possible that man's activities

Simulatiolls of the Effects of Climate Challge

220

have changed the sulphur cycle in a profound way, with resultant effects on ecosystems. The "acid rain" problem is linked to this. For the present moment, extensive research activities are being undertaken which might contribute to a better understanding of the mechanisms involved. This work is an essential prerequisite to any future global monitoring. Extensive emissions both to air (NOx automotive emissions) to waters (sewage) and to the soils (artificial fertilisers) may have global importance. Changes in the phosphorus cycle may also be critical as this element may play an important role in the eutrophication of water. On the other hand phosphorus is an element which might be limiting to agricultural ~ductivity in the future and resource conservation and ma~ment may be very important. " An~lt&, critical substance is carbon, by some regarded as the limiting substance in eutrophication. Carbon dioxide levels in air are also of great importance for organic productivity. We are not yet prepared to recommend immediate implementation of monitoring programmes for the geochemical cycles, but research and pilot activities directed towards their inclusion at a later stage are recommended. On the basis of the foregoing considerations, first priority that data be collected on the following substances in air, water, soils and biota, at a number of stations for the purpose of assessing secular trends in relation to the pollution of the biosphere: Mercury. Lead. Cadmium.


221

DDT, its metabolites and degradation products. Polychorinated biphenyls (PCB). We further recommend that the following substances be considered for a later inclusion in this network. Petroleum products Persistent organochlorine compounds other than DDT Chlorinated phenoxy acetic acid derivates. Organophosphorus compounds. Chlorinated aliphatic hydrocarbons. Other metals (As, V, Zn, Se, Cr, Cu, Be, Ni, Mn). Relevant compounds in the cycles of 5, N, P and C. Oxygen in water. PHYSICAL, CHEMICAL AND BIOLOGICAL DATA

The interest expressed in the idea of environmental monitoring by various governments and by the world scientific community stems from a basic concern with the safe guarding of human health and well-being as defined in the very broadest sense, Le., any phenomenon which can be detected as a significant disamenity to man. Thus, apart from the direct harm to human health, arising from exposure to incipiently pathogenic agents (e.g. harmful micro-organisms, toxic substances) in air, water and food, indirect harm could arise from: certain forms of climatic change; a reduction in the productivity of crops; other changes in livestock and biota; modified aesthetic values and environmentally induced social problems. This is the total human environmental problem and further clarification is required to obtain a more practical view of human health in the context of the present discussion.

222


The indirect effects referred to above, Le. any future climatic change or future reduction in biological productivity, can influence nutritional and living-standard factors, which could predispose man to succumb more readily to pathogenic agents on a much wider scale in the future than he does at present. The action of such indirect effects in areas of the world where because of adverse local climates or poor soils, underfed populations living in extreme poverty exhibit high moribundity and mortality rates from pathogenic agents. Such nutritionally generated health problems have been with us for many years, aggravated by bad housing, defective sanitation and pest-infestations. Existing national and inter-governmental health organisations still recognise this as their basic area of involvement and continue to be very active in this field. Apart from this more traditional area of concern, there exists a strong feeling that nowadays, man may be exposed to an additional and growing burden of environmentally induced health hazards generated by his intensive agricultural and urban-industrial use of the environment. Thus, superimposed on the patterns of disease characteristic of pre-urban-industrial or pre-intensive agricultural societies can discern a newer component which is either known or suspected to be induced by exposure to these 20 th century conditions. They include: diseases of the blood and circulatory system (e.g. anaemia, hypertension, arteriosclerosis and is chaemic heart disease): certain forms of cancer (e.g. leukaemia, kidney, liver, stomach, lung, bladder); respiratory complaints (e.g. asthma, emphysaema, chronic bronchitis); impairment of nervous function (e.g. encephalopathy, mental disorders); teratogenic effects (e.g. congenital malformations) and mutagenic or allergy effects.


223

The possible causal agents here are generally agreed to be one or more of the following, some less certain than others: oxides of sulphur and nitrogen, ozone, carbon monoxide, non-ferrous metals (e.g. Pb, Hg, Cd, As, Be, Ni, Zn, Cr); radionuclides; nitrates and nitrites; organochlorine compounds (e.g. pesticides, chlorinated dioxans, polychlorinated biphenyls, chlorinated aliphatic compounds) and other more or less complex pharmaceutical substances and food-additives with poorly understood side-effects. It is generally agreed that we need a more thorough registration of morbidity and mortality attributable to these diseases or some form of index-parameters to these (e.g. crude morbidity and mortality rates in excess of normalised data, perinatal mortality, rates of first admission to mental-care as against re-admission rates). This survey may be carried out in four broad strata or critical groups:

Very high exposure groups at special risk from the suspected causal agents listed above. High exposure groups below occupational exposure levels but having higher than average exposure on account of living in large cities, or intensively industrial or agricultural regions. Medium exposure groups living in rural parts of densely populated countries with a high level of technology and/or intensive agriculture but not at risk levels (a) or (b) above. Low exposure (baseline) groups living in remote regions of the world practising primitive agriculture, pastoralism or hunting. Along with such studies, a simultaneous programme of exposure assessment should be conducted. This would

224


attempt to evaluate the levels of the suspected causal substances in the local air, food (including imported foodstuffs) and drinking water and relate it to the levels actually present in huma.n tissues (e.g. bone, liver, kidney, spleen, blood, skin, hair, body fat). It is important here to analyse materials for as many substances as possible at the outset. Multifactorial statistical processes will later enable the investigators to concentrate on a priority list of two or three substances for each disease category. The ways in which such causal substances accumulate with age in the various categories (a) - (d) above has already proved valuable for Cd and Pb. This kind of knowledge, acquired directly from field studies can be effectively supported by long-term chronic toxicological studies carried out on experimental animals in order to induce experimentally the various types of illness by the administration of trace amounts of suspected causal agents, over several generations if necessary. Another valuable experimental approach is a biochemical search for impaired enzyme activity, the apperance of intermediate metabolites accumulating in tissues or body fluids of affected organisms, including man, as a result of impairment of metabolic function (e.g. D-aminoIaevulinicacid dehydrogenase activity and the appearance of this acid in urine of lead intoxicated subjects). This combined field- and experimental- approach helps to associate with more certainly each disorder with its specific causal agents. It also provides information on what threshold levels of each substance are harmful to human health. Without these critical values it will not be possible to assess the seriousness of current global levels of the various substances and much time and/f'esources will be wasted in a costly and elaborate monitoring process which cannot be evaluated.


225

Many technical problems exist in obtaining representative sampling, natural ranges of genetic tolerance, synergistic effects and the computation of reliable threshold dose levels. This latter difficulty has been avoided for radionuclide exposure by adopting the simple concept that there is no zero-effect dose of a radionuclide and that all exposures are cumulative and additive with an effect proportional to the final dose received by the body or population studied. This operational concept used by UNSCEAR and IRCP of calculating the so called "overall harm commitment" of population and relating it to a stochastic index of damage to a human population merits attention for pollutants. There is already some evidence indicating thai some pollutants may act like radionuclides are supposed to behave in having no toxicity threshold, and attempts to follow this radionuclide approach for contaminants such as lead or methyl mercury. Again it is important to recognise from the outset that in assessing "total harm commitment" for contaminant it is necessary to make an "ecological" approach to the dynamics of the substance studied. Thus, one must know its rate of supply to the body via food-webs, its absorbtion rates in gut and lung, its elimination rate by the body as well as its environmental stability or persistence. It is also important to continue to review new chemical substances for their possible long term harm to man.

In the light of the above remarks the following be periodically surveyed wherever data can be obtained: Human life expectancy. Population age-structure. Excess crude mortality.

226


Growth rate in terms of body weight and height. Frequency of diseases of blood and cardio-vascular system (anaemia, is chaemicheart-disease, arteriosclerosis, hypertension). Frequency of certain forms of cancer (leukaemia, cancer of stomach, liver, kidney, bladder, lung). Surveys should be carried out in various age groups and in the following four critical groups representing various degrees of exposure: - Very high exposure (occupational). High exposure (urban-industrial, or intensive agricultural exposure). Medium exposure (rural populations in densely populated countries). Low exposure (populations from remote regions). A simultaneous programme of tissue analysis (bone, blood, liver, kidney, spleen, body fat) for lead, mercury, cadmium, DDT and its metabolites, polychlorinated biphenyls, should be carried out on postmortem and other material, carefully selected to represent various age-groups and levels of exposure. Data collected under 1-6 above should be correlated using traditional threshold-dose-Ievel quality criteria and also attempts made to use the "no zero-dose effect" method used for radionuclides. We recommend a periodic review of other potentially hazardous substances, including new chemicals, to help determine whether they have any long-term effect on human health. We recommend research to establish biochemical monitors of disease e.g. accumulation of intermediate metabolites in the human body.


227

BIOLOGICAL SYSTEMS

Relevant physical and chemical measurements of the abiotic environment will not in them selves be informative concerning actual effects on biota. The rationale for monitoring animals and plants and their associations is that only by doing this. Moreover, the whole concern about the environment has evolved because from time to time directly adverse effects on biota and man have been observed. Biological parameters therefore constitute an indispensible, if not the most important part of any comprehensive environmental monitoring system. Monitoring of the physical or chemical properties of the environment is relevant only in conjunction with established or strongly suspected effects on biota. The view taken in this report, that biological parameters constitute effect parameters means that there is motivation for biological mor itvring even if a direct and specific cause and effect relationship has not yet been established. Observed adverse d"'a!1ges in the living environment will provide warning signals and detection mechanisms and will draw attention to the fact that research is needed to clarify the underlying cause as a preparation for corrective management. Biological systems are extremely complicated and possible variables for monitoring very numerous. It is thus essential to fmd those biological variables that most efficiently provide reliable information about effects on biota. First the feasibility of performing observations and measurements most likely to be informative and then, by developmental research, further refme them into workable parameters. The effects on biota that need to be monitored are caused by (1) more or less direct human impact, (2) climatic changes and (3) biologically active chemicals

Simulations of the Effects of Climate Clumgt

228

introduced into the environment. The variables selected should be informative regarding at least one of these three groups of causes. The biological parameters may be sought at different levels of biological organisation, from the lowest level of molecules, via populations to the levels of whole communities and biocoenoses. When looking into the problems at the highest levels it is necessary to take the totally integrated picture of the biotic and the abiotic environment into consideration. Therefore studies on ecosystems and biomes must be carried out and the biological monitoring activities integrated with physical and chemical monitoring. Our approach here will be to make a broad review of different possible areas where effects can be expected and to isolate those where monitoring is both feasible and relevant. The following list includes those kinds of biological parameters that will be considered in the evaluation of a minimum programme. Biomestudies. Distribution of vegetation types. Species diversity. Primary productivity, biomass and growth rate. Size and distribution of species populations. Specific population characteristics: reproductive success, mortality, age structure and migrality. Physiology, ontogeny and pathology. Genetics. Behavioural responses and mental performance. Phenology. Registration of short lived biological phenomena.

Environmental Monitorillg

229

Biome studies. It is an impossible task to analyse each of them separately. However, there is enough evidence to indicate that a number of basic principles are the same over large regions with roughly similar ecosystem structures, e.g. within tundra ecosystems or within tropical forest ecosystems. Regions with similar ecosystems are called biomes, and the logical approach is to call for studies in representative ecosystems within each biome, i.e. biome studies. From the monitoring point of view, biome studies should provide information on where in the total circulation of energy and substances the critical points are located in terms of sensitivity to environmental stresses and to human control. Information of this kind is of great importance for the determination of the most efficient biological and other parameters for monitoring. By comparing states and processes of comparable ecosystems in low, medium and high exposure situations it will be possible to detect effects caused by human impact without time-consuming long-term monitoring at fixed plots. The biome studies will, if properly designed, constitute indispensible parts of a global monitoring programme as centres for research and analysis activities directed to the integrative evaluation of complex biological processes and to the isolation of specific parameters suitable for large scale routine monitoring.

Distribution of vegetation types. The surface of earth is continuously changing. Ecosystems are disappearing and being replaced. It would be an important task to make repetitive surveys of the occurrence and distribution of different ecosystems on a global scale.

Species diversity. It is well known that one of the major cri,teria for the health of ecosystems is their degree of

230


stability. A useful measure of the degree of stability is species diversity. Agents causing environmental damage generally cause decreased species diversity. Measurements of species diversity are difficult to carry out expect for very limited parts of total biota. The soil still remains the most important and intensively used part of the biosphere, and soils are not renewable in the same way that air or water is. Toxic substances often accumulate in soils and changes in soil quality tend to be more or less irreversible. It is therefore particularly important to detect changes in soil quality as early as possibble. The programme should include sampling of representative soil transects from low exposure to high exposure situations in relevant biome types. Identification of species will generally not be possible and therefore the relative occurrence of different ecological groupings of organisms has to be used. An interim approach to soil health monitoring pending the development of methods for a more detailed programme is to use grosss oil respiration as an index of biological activity of soils. Aquatic algae often show very early and characteristic reactions to changes in the physical and chemical properties of water. They are particularly sensitive to increased levels of nutrients but also to toxic chemicals. Paricular attention should be paid to changes of the algal communities in the marine environment, since changes there may mean that global effects of pollution are occurring. Air plankton (pollen, fungal spores, bacteria, etc.) are often carried long distances by moving air masses. The quantitative and qualitative composition of air plankton may provide information on the movements of specific air masses across continents, assist in forecasting animal and plant diseases and allergies in man and contribute to the detection of major changes in the general composition of vegetation and microfauna and microflora.


231

Primary productivity, biomass and growth rate. These variables depend primarily on climate, water and soil quality but may also be affected by toxic chemicals. It seems however that the prospects for detecting effects of human impact upon these parameters are not great. Natural ecosystems have generally a high buffering capacity and modified ecosystems are generally managed with the purpose of preventing changes of any kind. However, these are a group of parameters that should be carefully analysed in connection with the biome studies for possible future inclusion in the routine programme. Size and distribution of species populations. One of the most characteristic and significant adverse effects of man's impact on the environment is that many species decrease in number or in distribution range. Some species even become extinct. These effects have been observed particularly in birds and mammals but also in other vertebrates, plants and in some invertebrates and microorganisms. The decreases in population size in many birds, particularly birds of prey, as a consequence of reproductive failure induced by mercury compounds and organochlorines have been particularly instructive. These decreases in population size, whether caused by toxic chemicals or by other forms of human impact, have been of tremendous importance in establishing the present concern about the environment. When looking further into the problems of defining suitable organisms it is recognised that a very restricted number of groups are suitable for monitoring. These groups are: (1) Vanishing or endangered vertebrates, because they are sensitive to environmental changes and because monitoring programmes already exist which have provided useful information, and (2) Birds,. because they have proved to be responsive to a wide range of environmental changes, because they are easy to monitor

232


(taxonomically well known and easy to count) and there are numerous reputable ornithological organisations capable of taking part in a programme at minimum cost.

Specific population characteristics: reproductive success, life expectancy, mortality, age structure and migrality. Certain specific population characteristics may often be detected much earlier than changes in population size or distribution because most species reproduce at a rate much higher than necessary to keep the population level constant. It is now known that the decreases in population size of many birds of prey is caused by reproductive failure, i.e. decreased natality. However, it takes some time before this affects the population size. Increased mortality has been observed for many animal species without accompanying population decreases. Life expectancy and age structure are important from the point of view of evaluation of the cause and effect relationship. Migrality is also necessary in the same context.

Physiology, ontogeny and pathology. Organisms respond to environmental stresses in many different ways. Effects of air pollution can be detected in the blood of vertebrates, congenital malformations are known to be partly environmentally induced and it is well known that plants react to different toxic substances with sometimes very specific pathological symptoms. We believe that the use of certain sensitive plants for the detection and monitoring of effects from air and other forms of pollution is promising. In many cases naturally occurring plants such as mosses, liverworts, lichens, may be used, particularly in high exposure situations. Promising results have been obtained with specially planted species selected either because of their general sensitivity to pollutants or because of their specific sensitivity to certain other substances.


233

Genetics. A number of substances released into the environment including the radionuclides are known to cause genetic changes, either affecting genetic variability or mutation rates. A number of possible ways to monitor the effects of such substances: studies of the genetic variability and mutation rates of a number of natural and laboratory populations of standard strains of animals, plants and micro-organisms. Suitable organisms include genetically well known standard strains of cultivated plants, Musca, Drosophila and laboratory mice and rats. There are however for the present no preparations for such a programme. It is known that some organisms may rapidly become adapted to tolerate elevated levels of toxic chemicals. This property provides a possibility of determining recent history of exposure by tolerance bioas says or by following gene-linked morphological changes as with industrial melanism.

Behavioural responses and mental performance. Extremely early effects from low levels of toxic chemicals can be detected on a laboratory scale in the behaviour and performance of animals, for example in relation to mating behaviour, learning ability. The techniques available are however not yet standardised. Phenology. The biological effects of climatic change are expected to be apparent first as changes in the seasonal timing of different biological phenomena (flowering of plants, arrival of migratory birds, mating, pupation and flying of insects etc). Extensive observations have been made of regional and local variations in time of flowering of widely distributed and genetically uniform species such as the common lilac (Syringa vulgaris). German foresters have made extensive use of phenological observations in the

234


planning of forest operations. Worldwide studies of phenology were proposed as a part of the International Biological Programme, but this work was carried out only in a few countries. Such a programme requires a large number of observations with a representative geographic distribution. A principal advantage of the use of phenology in environmental monitoring is that many competent amateur observers can be enlisted. It might also be possible to use remote sensing techniques for registering the flowering of certain trees.

Short-lived biologicalphenomena (local catastrophes). A number of short--lived biological phenomena may serve as very informative detectors of unknown environmental problems. Extensive kills of sea-birds have occurred from time to time along most coasts of the world. To some extent they may be caused by bad weather conditions but toxic chemicals and/or heavy metals have been supposed to constitute an important contributary factor. Thus, such observations may deserve monitoring in order to be reported in a systematic way so that research efforts can be diverted to the problem immediately in order to find out what the cause was. If the results show that some neglected environmental factor was responsible, it should be decided whether it deserves more or less permanent inclusion in the monitoring system. Other short-lived phenomena that could be mentioned as possible candidates for inclusion into the reporting system are sudden plankton blooms in the oceans, certain kinds of pest outbreak, certain rapid and unexpected species extinctions etc.

12 Costs of Climate Change Mitigation Climate change due to the enhanced greenhouse effect is likely to be the most significant environmental issue confronting the global community in the twenty first century. Of all industrialised countries, Australia is one of the most vulnerable to the impacts of climate change. This reflects Australia's already variable climate, poor soils, vulnerable ecosystems and high proportion of population living in coastal areas. Thus the potential impacts of climate change and the need to develop appropriate adaptation strategies are now important considerations in the context of national, state and local government responses to the issue. The economic costs of climate change mitigation are relatively well understood, as are the sectors and industries most likely to be affected by mitigation policies and measures. By contrast, the economic costs of climate change impacts are not well understood. It is essential that economic assessments of climate change are framed in the context of a sound appreciation and understanding by decision-makers of all of the potential costs and benefits associated with climate change and climate change response. Once the costs of climate change impacts and net benefits of adaptation strategies

236


are better understood, decisions can be made about the most appropriate combination of mitigation and adaptation measures. REASONING FOR COSTING CLIMATE CHANGE IMPACTS

Climate Change Response Rationale

Climate change due to the enhanced greenhouse effect is likely to be the most significant environmental issue confronting the global community in the twenty first century. The Third Assessment Report (TAR) of the Intergovernmental Panel on Climate Change (IPCC), released in 2001, confirms that the global climate "has demonstrably changed 011 both global and regional scales since the preindustrial era, with some of these c1u/llges attributable to human activities".

The TAR also stresses that, even with concerted international action to reduce greenhouse gas (GHG) emissions, further global warming is likely to occur over the next few decades leading to regionally and locally significant impacts. An IPCC special report, 'The Regional Impacts of Climate Change: An Assessment of Vulnerability', indicates that Australia is one of the most vulnerable of all industrialised countries to the impacts of climate change. This reflects Australia's already variable climate, poor soils, vulnerable ecosystems and high proportion of population living in coastal areas. The TAR has confirmed the vulnerability of a range of ecosystems, economic sectors and communities in Australia to climate change including, in particular: water supply and hydrology; natural ecosystems including:

Costs of Climate Change Mitigatioll

237

coral reefs forests and woodlands alpine systems; wetlands riverine environments;' agriculture, forestry and fisheries; coastal settlements and the built environment; energy sector human health; and tourism. Thus the potential impacts of climate change and the need to develop appropriate adaptation strategies are now important considerations in the context of national, state and local government responses to the issue. The Australian Government has recognised the importance of impacts and adaptation with the establishment of a National Climate Change Adaptation Programme in 2004. This programme aims to prepare all spheres of government, vulnerable industries, communities and ecosystems to manage unavoidable consequences of climate change. The Adaptation Programme is closely linked with the Australian Greenhouse Science Programme, which improves the scientific understanding of the causes, nature, timing and consequences of climate change to better inform industry and government decisionmakers. The AGO release, in 2002, of 'Living with climate change', which provides an overview of the potential impacts of climate change in Australia, and a more recent AGO publication 'Climate Change. Economic Rationale

Any external 'shock' to the economic system (such as climate change) can be examined in terms of:

238

Sillll/latiolls of tile Effects of Climate Challge

first, the (hypothetical) costs if individuals, companies and governments take no action to avoid or reduce the costs associated with that shock; or second (more likely), the costs if action is taken to avoid at least some part of these costs by mitigating the size of the shock itself or by adapting to the shock as efficiently as possible - the assumption being that economic agents are flexible and will act to reduce the costs of an external shock. Both mitigation and adaptation involve investment and other costs and both provide benefits in terms of lower impact costs. In relation to the climate change issue, the economic costs of climate change mitigation are relatively well understood, as are the sectors and industries most likely to be affected by mitigation policies and measures. By contrast, the economic costs of climate change impacts, the sectors likely to be affected and the costs and benefits (Le. net benefits) of adaptation measures are not well understood. It is essential that economic assessments of climate

change are framed in the context of a sound appreciation and understanding by decision-makers of all of the potential costs and benefits associated with climate change and climate change response. The assessment of costs of climate change impacts and net benefits of adaptation strategies is most appropriately undertaken as a two-staged process, with the focus in _the first stage being on identifying the concepts, issues and methodologies appropriate for a robust analysis. Once these concepts, issues and steps have been identified, decision-makers can then proceed with the more expansive and involved task of costing the impacts of climate change, under a range of scenarios, at the regional, sectoral and national levels. Once the costs of climate change impacts

Costs of Climate Change Mitigation

239

and net' benefits of adaptation strategies are better understood, decisions can be made about the most appropriate combination of mitigation or adaptation measures. FRAMEWORK FOR CLIMATE CHANGE CHANGE ADAPTATION

The purpose of this chapter is to examine and establish an appropriate framework for costing the impacts of climate change and climate change adaptation. This framework consists in turn of: the economic framework for the assessment - welfare economics remains the most coherent and consistent framework for valuing, in dollar terms, the impacts of climate change; the objectives and scope of the assessment; and baseline definition. Economics Framework Welfare Economics

The foundation of all economic analysis is that scarcity necessitates trade-offs between alternative resource us~s. The trade-offs are made on the basis of the value of the resources to individuals and society. This value is determined by individual preferences, with the total value of any resource being the sum of the values that individuals place on its use. Individual preferences can be expressed in two equivalent ways: willingness to accept (WTA) - the minimum payment that the owner of a resource is willing to accept for its use - with marginal WTA being represented diagrammatically in economic analysis as a supply curve; and

240

Si/lllliatio/ls of the Effects of Climate Challge

willingness to pay (WTP) - the maximum amount a consumer is prepared to pa~ for using the resource with marginal WTP being represented diagrammatically in economic analysis as a demand curve. Thus if applied in the context of costing the impacts of climate change, WTP measures the maximum people would be willing to pay to avoid a particular impact (by adopting, for example, adaptation or mitigation strategies), while WT A measures the minimum people would be prepared to accept (as compensation) for living with the impact. When measuring the costs of climate change impacts it is important that the cost assessment should consider all value or welfare changes as a result of the climate change impacts. In measuring welfare changes need to draw a distinction between economic (opportunity) cost and financial cost, and between social cost and private cost. The net economic LOst of a given climate change impact (or adaptation option) is the total value that society places on the resources that have been used to produce the goods and services forgone as a result of the impact (or of the resources diverted from alternative uses to adapt to the impact). These resources are measured in terms of the value of the next best alternative to which they could have been applied (i.e. the value of the opportunity foregone or opportunity cost - measured in tum by WTP / WTA). Thus economic costs may differ greatly from financial (accounting) costs which are simply a measure of the financial payments made for goods and services. The net economic cost of a climate change impact on society will comprise both the private costs (benefits) of the impact and the external costs (benefits). Collectively, these are defined as the social cost (benefit). Thus:

241


Social cost

= private costs

+ external costs

Where: Private costs are the costs internal to the individual consumer or producer arising from the impacts of climate change. These will typically be measured in terms of changes in 'consumer surplus' and 'producer surplus' which arise from the impacts of climate change on consumer demand or producer supply of a good or service, where: consumer surplus is the value consumers place on a good or service over and above the purchase price; and producer surplus is the amount by which a producer's revenues from selling a good or service exceed production costs. External costs are costs that are external to the market. Many of the environmental, health and social impacts of climate change will fall into this category. Within a welfare economics framework, it is the social cost of climate change impacts that represent the full economic costs of impacts and therefore will determine the most economically efficient policy response. Analysis to Economic Assessment

Within the welfare economics framework, there is a spectrum of approaches or levels of analysis that can be used to assess the costs of climate change impacts. As we move through that spectrum the level of detail and completeness provided by the analysis increases, as does the level of complexity of the analysis. The two main levels of economic assessment are as follows: Partial equilibrium analysis. The impacts of climate change or adaptation policies and measures can be

242

Simlliations of the Effects of Climate Change

examined in terms of direct effects on the economic value of a single market for a good or service. Consumer and producer surplus are the measures typically used to estimate economic value. There are number of economic valuation techniques that can be applied to valuing the impacts of climate change on an industry or market within a partial equilibrium framework. Economic valuations can be undertaken at a level that is detailed enough to provide analysis of the specific workings of a market or industry. However, flow-on effects and feedbacks between the target market and the rest of the economy are not captured in these valuation studies. This requires the use of general equilibrium analysis. General equilibrium analysis. Where the impacts of climate change on a market result in indirect economic impacts or economic flow-on effects throughout the economy or where the impacts of climate change are being assessed for number of markets or industries, then general equilibrium analysis should be used. Macroeconomic (input-output) modelling and Computable General Equilibrium (GCE) modelling are the two main approaches to general equilibrium analysis. It should be recognised that these approaches are not

mutually exclusive. Thus, in practice, the results of the results of an economic valuation assessment or partial equilibrium analysis can be used as input into a general equilibrium analysis. Economic efficiency and Decision-making

Economic efficiency is only one outcome that is likely to guide decision-making on climate change and responses to the impacts of climate change. This is because other societal objectives may not be captured fully in the welfare

Costs of Climate Cha1lge Mitigatioll

243

economics approach to costing climate change impacts. Some analysts argue that an efficient response to the impacts of climate change - in the sense that nobody can be made better off without someone being made worse off - does not guarantee an equitable outcome. Thus there may be a trade-off between an efficient policy response and an equitable one. Another issue often raised in relation to welfare economics is that, notwithstanding the use of hypothetical market techniques such as contingent valuation it cannot adequately measure the non-use values of natural systems or the extent to which human-produced stocks of capital may not be substitutable for natural capital stocks. Regardless of these limitations, welfare eco!\omics when extended to address externalities, uncertainties, equity etc - provides the best framework for placing a dollar value on the impacts of climate change, encompassing a consistent and flexible set of methods and tools for costing most impacts. There are however, alternative or complementary tools or methods for assisting decision-making on the impacts of climate change and climate change response more generally, including multi-criteria decision analysis. Objectives and Scope of the Assessment

It is crucial that the objectives and scope of an economic assessment of the impacts of climate change are fully defined prior to any assessment being undertaken and that these reflect the problem at hand. The objectives and scope of the assessment are a function of the decision problem, which in turn relates to: the decision-making context - and associated baseline; the climate change impacts to be Ineasured - their type and geographic scale.

244

Sill/ulatiolls of tile Effects of Climate Challge

Decision-making Contexts

There are essentially two decision-making contexts in which the cost estimates of the impacts of climate change are likely to be used: Impact assessment/prioritisation. The objective is to produce estimates of the net economic costs of climate change impacts, for the purpose of establishing the relative importance of different impacts or possibly of establishing the significance of impact costs relative to mitigation costs. Adaptation option appraisal. The objective is to produce estimates of the net benefits of adaptation to specific climate change impacts for the purpose of choosing between different adaptation options. For each of these contexts a baseline (or reference scenario) needs to be specified.

Baseline Specification for Impact Assessment As previously noted, the objective in this context is to estimate the net economic costs (positive or negative) of climate change impacts in the absence of adaptation measures. The baseline (or reference scenario) can be defined as the situation assumed to exist (in a system, sector, industry or region) in the absence of climate change (the 'without climate change' case). The difficulty with baseline specification is that there are potentially two different baselines which can be used to cost the impacts of climate change: A static baseline (or fixed reference scenario) assumes that existing socioeconomic, environmental and physical conditions will continue to prevail in the study sector or region into the future. Using the impact of climate change on tourism to the Great Barrier Reef as an example, the use of a static baseline


245

would assume that current tourism levels will continue into the future and the costs of climate change to tourism in the region are therefore the difference between the current net benefits of tourism and the net benefits of tourism with climate change. Due to expediency, this static baseline approach has been frequently used in studies of the costs of climate impacts. As noted by Metroeconomica however, the use of a static baseline is an unrealistic representation of the future. A more realistic approach is one that uses a dynamic (or moving) baseline to describe the future without climate change. This requires constructing realistic projections of future environmental, social-economic and physical conditions relevant to the study sector or region. Baseline Assessment for Adaptation Option Appraisal

The baseline (or reference scenario) is the future impacts (and associated costs) of climate change in the absence of adaptation. The effect of the adaptation response is to reduce the impact of the climate change on the system or sector, with the reduction in the cost of the impact representing the net benefit of the adaptation response. In this way, the net benefits (or costs) of different adaptation responses can be compared. Impacts of Climate Change on Systems

A sound understanding of the likely or simulated impacts of climate change on systems, sectors and/or regions is obviously an essential prerequisite for any assessment of the costs and benefits of those impacts. This includes an understanding of the following: The type of impacts to be costed. Climate change will generally involve a spectrum of impacts from direct

246

Simlliations of the Effects of Climate Change

impacts, such as warmer atmospheric and ocean temperatures, through to indirect biophysical impacts on natural systems, and socio-economic impacts on human systems and sectors. For each impact, 'exposure units' will be affected. Generally, the economic analyst attempting to value the impacts of climate change will, for any system or sector, seek to value all of the impacts along the spectrum. This may not always be the case though, particularly if the decision-making context is the assessment of the costs and benefits of different adaptation responses to a specific impact. One issue confronting the analyst is that the extent to which all impacts can be quantified across all exposure units will vary considerably depending on the level of data aggregation and the level of uncertainty associated with the impacts. The geographic scale of the impacts. Decisions about the geographic scale of impacts to be valued (e.g. local, regional or national) will both influence and be influenced by the level of data aggregation and accuracy and the method of valuation used. Close liaison between economic analysts and scientific community will be important, not only to understand the spectrum of impacts relevant to a particular economic assessment but also the risks and uncertainties associated with those impacts. ECONOMIC TeCHNIQUeS

Applying Techniques

The economic valuation techniques can be used to cost local or regional scale climate change impacts on a single industry or market, within a partial equilibrium framework. Because they use disaggregated data, studies


247

drawing on these techniques are sometimes referred to as 'bottom-up' studies. The techniques have the advantages of being: flexible, in the sense that they can potentially be applied to a wide range of impacts, sectors or markets; and relatively straightforward to apply (e.g. they do not require complex economic models). However, the use of these techniques in isolation is predicated on an assumption that a climate change impact will not lead to price changes in the affected market. Where climate change is likely to lead to a change in output or demand for a good/service that is significant enough to affect its price, then the measurement of changes in producer or consumer surplus will require knowledge of the demand and supply functions that exist in the particular market. This, in turn, will require information on the price elasticity of demand for the affected good or service. This additional analysis will often require the processing of significant amounts of information, although this can generally be done by means of a simple model. If the impacts of climate change are expected to have economic flow-on effects then general equilibrium analysis will be required. General equilibrium analysis could draw on information derived through economic valuation studies. Discussion of Techniques

Although there is no established categorisation of economic valuation techniques, they can generally be grouped into two major categories - methods that use 'directly observed market behaviour' and methods that draw upon 'hypothetical market behaviour'.

248


Direct Observation Direct observation methods use the prices for goods and services that are traded in the market to estimate producer and consumer surplus and thereby directly or indirectly infer cost or value relating to the affected good or service. For example, in calculating the economic impact of climate change on commercial fisheries in the Great Barrier Reef, an observed market method might calculate how much the catch is valued in the market and use an estimate of how much catch may decline in the future (as a result of the loss of coral reefs and other impacts of climate change) to value lost consumer surplus. In this case, prices of the affected 'good' (fish) are observed and their use allows the direct estimation of loss in value. These methods are sometimes also referred to as 'revealed willingness to pay' methods since willingness to pay is 'revealed' through market prices. Direct observation methods can, in turn, be split into two further categories: Direct markets will cost climate change impacts using the market price of the affected good or service which has been obtained in a conventional market through the forces of supply and demand. Methods in this category include: estimates of the change in input/output of a market; and estimates of replacement or restoration costs. Indirect markets will cost climate change impacts by observing behaviour in surrogate markets for an affected good or service. These surrogate markets can be applied to the impacts of climate change when changes to the flows of valued 'services' are not priced in conventional markets, such as impact of climate

Costs of Climate Challge Mitigatioll

249

change on the value of recreational fishing or diving in the Great Barrier Reef. Many environmental and social services fall into this category. Methods include: the travel cost method; and hedonic pricing.

Hypothetical Markets Hypothetical market methods are generally used when value is not directly observable in the market, as is the case with 'non-use' valuess. For example, the non-use values of coral reef ecosystems are not directly observed in the market. To estimate these values, survey questionnaires can be used to directly or indirectly elicit individual valuations in a hypothetical or constructed market for the ecosystems. Hypothetical market methods are sometimes referred to as 'expressed willingness to pay (WTP), methods, since people are asked through surveys to 'express' their willingness to pay for a good or service based on a hypothetical scenario. Methods in this category include: contingent valuation (direct valuation); choice modelling (indirect valuation). The different categories and types of costing techniques are discussed further below. Change in Input or Output of Markets

In many cases climate change could have a direct impact

on: the ability of an economic agent or pro.ducer (e.g. a commercial fisher, a farmer or a tourist operator) to produce a good or service; and/or

250

Simulatiolls of the Effects of Climate Clumge

the costs that the agent incurs in producing that good or service. For example, if climate change led to loss of coral reefs on the Great Barrier Reef, which in turn led to a decrease in fish stocks, commercial fishers could either: allocate more resources in order to maintain current harvest rates; or more likely reduce the size of their overall catch. Either way, the commercial fishers will suffer economic loss. This loss can be measured as the costs of the increased resource inputs - known as the 'production cost technique' or as the value of decreased output - referred to as the 'change in productivity approach'. The choice of approach adopted will depend on the anticipated response of the producer to the impact. There are a number of ways in which changes in production costs or productivity can be measured. These include: measuring gross margin for each unit of output and multiplying by the estimated change in output as a result of climate change impacts; in the case of agriculture, estimating the changes in land values with and without climate change impacts (as rural land values are linked to the land's productive capacity); calculating the unit costs of resource inputs, such as labour or natural resources, and multiplying by the projected change in resource use; and using the total budget approach to estimate the difference between net income (the value of gross output minus the cost of gross resource inputs) with and without climate change impacts.

Costs of Climate Change Mitigati01l

251

Examples in Australia of the application of these methods to cost the impacts of climate change include: Beare and Heaney, who as part of study into climate change and water resources in the Murray-Darling Basin (MOB), modelled changes in net returns (total budget approach) to estimate the loss in agricultural returns arising from the impacts of climate change on water availability and salinity. Howden, Reyenga and Meinke, who estimated changes (generally increases) in gross margins for wheat cropping arising from increases in yields due to a doubling in CO2 concentrations and temperature increases. Restoration Costs

Another group of direct market methods relying on observable market behaviour that can be used to estimate the costs of climate change impacts are the preventative expenditure and replacement cost techniques. Preventative Expenditure

The preventative expenditure technique measures the expenditure incurred in order to avert damage to the natural environment, human infrastructure or to human health. The technique can be used to measure the impacts of climate change on both marketed and non-marketed goods and services, with the exception of non-use values. In terms of costing climate change impacts, preventative expenditure should be seen as a minimum estimate of impact costs since it does not measure the consumer surplus. Preventative expenditure, if undertaken, would in reality be an adaptation cost, since it is an expenditure aimed at reducing the impacts of climate change. As such, great care needs to be taken if using the technique in the context of a cost-benefit analysis of adaptation options.

252

Simulations of the Effects of Clinuzte Cluznge

Replacement Cost Technique

The replacement/restoration cost technique can be used to measure the costs incurred in restoring or replacing productive assets or restoring the natural environment or human health as a result of the impacts of climate change. As with preventative expenditure, restoration costs is a relatively simple technique to use and has the added advantage over preventative expenditure of being an objective valuation of an impact - i.e. the impact has occurred, or at least is known. Use of the replacement costs method relies on replacement or restoration measures being available and the costs of those measures being known. As such, the method is unlikely to be appropriate for costing the impacts of climate change on irreplaceable assets such as biodiversity or cultural heritage or indeed, the loss of a human life. Another shortcoming with the technique is that actual replacement or restoration costs do not necessarily bear any relationship to willingness of individuals' to pay to replace or restore something. This can be seen in relation the potential health impacts of climate change - the health service costs incurred to restore the health of someone made ill by a tropical disease may be less than that person's WTP to avoid getting the disease in the first place. Hedonic Pricing

Hedonic pricing is an indirect or surrogate market technique that attempts to judge individuals' value for a non-marketed good or service by observing their behaviour in related markets. The two markets often used for hedonic pricing are the property market and the labour market. The hedonic property value approach attempts to measure the welfare effects of changes in environmental goods or services by estimating the


253

influence of environmental attributes on property prices. The method assumes that people buy property for different attributes such as size, quality and proximity to work, and that some of these attributes, such as views, proximity to parks and local air quality, relate to environmental values. By estimating the demand and prices of properties with different sets of attributes, it is possible to estimate how much a specific environmental attribute, such as coastal views, is valued by people. Econometric models are generally used to isolate the effects of specific environmental attributes on property prices. This 'hedonic property price function' is then used to infer how much people are willing to pay to protect that environmental attribute. In the context of costing the impacts of climate change, the method has already been used internationally to assess the costs of climate change on coastal resources. It could also potentially be used to assess individuals' WTP to protect valued scenic areas from the impacts of climate change or possibly even their WTP to live in a particular climate zone. The hedonic wage risk approach is applied to wage rates to measure the value of changes in health (morbidity and mortality) risks. It involves identifying a relationship between the risk of death in a job and the wage rate for that job. This method can potentially be applied to costing some aspects of the impacts of climate change on human health and life expectancy. The main strengths of the hedonic pricing methods outlined above are that they rely on observed markets and that they can be applied to quite a wide range of environmental and social values. One weakness of the methods is that results of hedonic studies are very sensitive to assumptions used in the econometric modelling of the price function. A further weakness is that

254


hedonic pncIng studies, to be rigorous, will generally require the collation of a comprehensive and relevant database for the relevant market. The process of collecting this data can be expensive and time-consuming. Travel Cost Method

The travel cost method is another method that attempts to infer value for particular environmental or social attributes from observed behaviour in related markets. The method has been commonly used both in Australia and overseas to indirectly value specific sites valued for their environmental and social amenities such as national parks, wetlands, rivers and heritage sites. The method uses information (often obtained from user surveys) on visitation rates and travel costs involved in people visiting a site (as a proxy for an admission fee) to predict changes in demand for the site in response to changes in travel costs. This data is then used to derive a. demand curve for the recreational services provided by the site and thereby the total benefits (consumer surplus) that present visitors derive from the site. For example, the travel cost method could be used to estimate the total consumer surplus enjoyed by present users of the Great Barrier Reef. Provided information on quality has been used to derive a 'whole experience' demand curve, it may then be possible to assess the impact on the visitation rate and consumer surplus of damage to the Great Barrier Reef due to climate change. Contingent Valuation and Choice Modelling Methods

In contrast to the methods discussed above, which all use observed data, the contingent valuation and choice modelling methods rely on surveys to elicit directly (contingent valuation) or indirectly (choice modelling) the values that respondents place on non-marketed environmental goods and services. ,

1 I

~


255

Contingent Valuation Method (CVM)

The contingent valuation method (CVM) involves directly asking people in a survey how much they would be willing to pay to protect from damage specific environmental or cultural services such as a national park, biodiversity, ecosystem 'or cultural heritage site. In some surveys, people are asked how much they would be willing to accept to allow the environmental service to be damaged or lost. It is called contingent valuation because people are asked to state their WTP /WTA, contingent on a specific hypothetical scenario. The CVM is probably the most widely used method to estimate non-use environmental and cultural values. It is also probably the most controversial nonmarket valuation method. Many CVM studies have been subject to considerable debate, especially over whether hypothetical markets adequately measured people's willingness to pay for environmental quality. In particular, studies using an openended elicitation format are often criticised for strategic bias, in that the respondents may have understated or overstated their true WTP /WTA in order to influence the decision-making process. Another criticism is that the CVM places individuals in the role of consumers rather than citizens and therefore cannot adequately capture nonuse values. Choice Modelling Method

The choice modelling method (often referred to as 'contingent choice') is similar to contingent valuation in that it can be used to estimate non-use environmental values and that it asks people to make choices based on a hypothetical scenario. However, it differs from CVM in that it does not directly ask people to state their values in dollar terms. Instead, dollar values are inferred from the hypothetical choices or trade-offs that people make. The

256

Simulatiolls of the Effects of Cli11Ulte Change

method asks respondents to state a preference between one group of environmental services at a given price or cost and another group of environmental characteristics at a different cost. Because it focuses on trade-offs among scenarios with different environmental outcomes, choice modelling is likely to be particularly suited to decisions involving a choice between different policy options or measures such as between different options for adaptation to climate change. Choice modelling has the advantages over contingent valuation of: allowing respondents to think in terms of preferences or priorities rather than directly expressing dollar values; de-emphasising price as simply another attribute and therefore allowing respondents to choose between attribute bundles that include price; and reducing the likelihood (If protest responses. Thus, when appropriately designed, choic~ modelling can minimise many of the biases that can arisE! in open-ended or discreet choice contingent valuation studies. A potential drawback with choice modelling is that by providing respondents with a range of attributes and possible options, the approach can increase the complexity of the task for respondents during questioning, making it difficult for them to evaluate preferences or tradeoffs. Also, the choice modelling approach requires more sophisticated statistical techniques to estimate willingness to pay than contingent valuation. A number of choice modelling studies have been undertaken in Australia recently, focussing in particular on valuations of wetlands and riverine ecosystems.


257

Benefit Transfer Method

In addition to the methods described above, the 'benefit transfer' method can provide a relatively low cost, 'shorthand' means of valuing non-market environmental and social benefits by transferring values derived in other valuation studies to the case study in question. For example, numerous overseas and Australian contingent valuation and choice modelling studies have been undertaken over the past 20 years examining the WTP of households or visitors to preserve different species, ecosystems or natural areas from real or perceived environmental threats. It may be possible, using the benefit transfer technique, to apply the results of one or more of these studies to an assessment of the economic costs of climate change on the ecosystems and biodiversity of the Great Barrier Reef. A major shortcoming with the benefit transfer method is that it relies on derived values from another source. Thus, great caution would need to be exercised when considering applying the values from other studies to assessing, for example, the economic costs of climate change on the ecological values of the Great Barrier Reef. Problems that could affect the validity of derived values include: differences between the species/ecosystem or other environmental 'good' valued in the source study and the species or ecosystems of the Great Barrier Reef; divergence in the magnitude of impacts under consideration; disparity of socioeconomic characteristics; and potential bias or other deficiencies with the source study.


258

In any case, it is rarely appropriate to directly trans~er aggregate value estimates from one study to another; some reworking of the original valuations being required. The NSW EPA database 'Envalue' provides a database of environmental valuation studies, including an overview of the studies and their potential application using the benefit transfer method. Adaptation Option

Once the net costs of climate change impacts have been assessed for a given market or sector, it becomes possible for decision-makers to value the benefits of adaptation to those impacts.By assessing the resource costs of different adaptation options (policies or programmes) then it becomes possible for the decision-maker to determine which adaptation option offers the greatest benefits relative to costs. There are two main techniques available for as~essing the relative costs and benefits of alternative adaptation responses (measured solely or principally in monetary terms): Cost-Benefit Analysis (CBA); and Cost-Effectiveness Analysis (CEA). A third available technique for assessing alternative adaptation options, in the_ absence of full information on monetary costs and benefits, is multi-criteria analysis. Cost-benefit AnalYSis

Cost-Benefit Analysis (CBA) is an economics decision support tool designed to show whether the total benefits of a project or programme, measured in economic terms, outweigh the costs of implementing that programme. It is the most widely accepted technique for determining the economic viability of a project. In the context of climate


259

change, CBA can be used to determine whether the total benefits of an adaptation response (policy or programme), measured in terms of reduced costs of the impacts of climate change, exceed the costs of the adaptation response. CBA methodology is well established, involving the following standard steps: Step 1: objective definition- define objective of project or policy. Step 2: option specification - specify and. define project options, including the base case (without project) option. Step 3: quantify costs and benefits - identify and quantify the negative effects (costs) and positive effects (benefits), including external effects, associated with each option. Step 4: value costs and benefits - value (price) cost stream and value benefits stream for each option using one or more of the methods. Step 5: NPV /BCR determination - determine the present value of the net benefit stream (NPV) and/or the benefit cost/ratio (BCR). Step 6: sensitivity analysis - conduct sensitivity analysis based on changes to assumptions affecting cost or benefit streams and discount rate. Step 7: distributional analysis - identify the distributional effects of each option. Step 8: assess non-monetary costs and benefits qualitatively assess costs and benefits which cannot be priced. Step 9: decision-making - make decision on preferred option based on NPV, distributional effects and nonmonetary costs and benefits.

260


Avoiding Double Counting of Benefits An important pitfall to avoid when conducting a costbenefit analysis is double counting of costs or benefits. This could well be an important issue when undertaking a CBA of adaptation options involving a range of impacts that are not mutually exclusive. Taking the example of impacts of climate change on the Great Barrier Reef again, these impacts are likely to include biophysical impacts such as loss of coral reefs and associated ecosystems, as well as socio-economic impacts on the commercial fishing industry and tourism. Double counting could occur when attempting to cost the biophysical impact (e.g. the loss of the reef system) by aggregating all of the dependant socio-economic impacts, or when assessing use and non-use values. This problem can be avoided by ensuring that the individual socioeconomic impacts are counted only once in the assessment process. \

Assessing all Costs and Benefits Another key issue is to ensure that all costs and benefits are fully addressed in the assessment. It is likely when assessing climate change adaptation options that many impacts of climate change will not have been quantified because of uncertainties about the extent of the impacts. Even if the impacts have been quantified, it is possible that certain non-market goods and services cannot be adequately valued in monetary terms due to difficulties with applying the surrogate or hypothetical market techniques discussed above. Lack of monetary estimates for climate change impacts however, should not mean that those impacts can be overlooked. As outlined in Step 8 above, non-monetary costs and benefits should be qualitatively assessed as part of the decision-making process.


261

The treatment of non-monetary costs and benefits is one of the major criticisms of CBA - either that they are overlooked in the analysis or that the process by which the non-monetary impacts have been assessed in relation to the monetary costs and benefits is not clearly established. One way of dealing with the issue of nonmonetary costs and benefit in the context of a CBA is to make transparent the process by which these costs and benefits have been assessed. Thus it would certainly be possible and acceptable with respect to some analyses of climate change adaptation options, for example, to stipulate that the known benefits of an adaptation measure clearly exceed the costs of adaptation even if some of the benefits have not been valued in monetary terms. The point here is that the application of CBA will not always require perfect knowledge of the monetary costs and benefits of climate change impacts. Another possible way of dealing with the absence of information on monetary costs and benefits is to combine assessment of monetary and non-monetary costs and benefits within a multi-criteria decision analysis framework. Proponents of multicriteria analysis argue that this is the best way of making transparent judgements about the relative importance of monetary and nonmonetary costs and benefits. Cost-effectiveness Analysis (CEA)

Cost-effectiveness analysis (CEA) is another economics decision support tool. It is generally used to determine the least-cost way of achieving a predetermined physical or environmental goal. It can also be used to identify a means of maximising an environmental or physical benefit for a given economic cost. An advantage that CEA analysis has over CBA is that it does not require a desired benefit of an adaptation to

262


be explicitly valued in monetary terms. Provided each adaptation option is likely to achieve the._same or similar level of benefit, only the costs of adaptation need to be monetised. Thus simplification of analysis is achieved. CEA is likely to have widespread application to the assessment of climate change adaptation options. --\

In general terms, the steps taken in applying CEA to assessment of adaptation options will be is follows: Step 1: objective definition - define objective or goal of adaptation project or policy. Step 2: option specification - specify and define adaptation options. Step 3: value costs - identify and value the costs (capital and recurrent) of each option. Step 4: quantify benefits - benefits of each option need to be quantified (but not valued) (e.g. ML of water delivered; km2 of foreshore protected; species saved). Step 5: cost-effectiveness - calculate the present value of the net incremental cost stream of each option per benefit associated with the option (e.g. $ per ML delivered). Results can be presented in the form of incremental cost (or supply) curves. Step 6: sensitivity analysis - conduct sensitivity analysis based on changes to assumptions affecting cost streams and incremental benefits. Step 7: decision-making - make decision on preferred option(s) based on cost effectiveness. CEA can potentially be applied to all levels of decisionmaking on climate change adaptation, from assessment of individual adaptation projects to regional or national level adaptation policies and strategies.


263

The techniques provide flexible and generally straightforward approaches to estimating the costs of climate change impacts or f~r assessing the costs and benefits of alternative adaptation options. The techniques are essentially limited to assessing the impacts on individual sectors or markets, although the results from these assessments (:an integrated into general equilibrium analysis. There are question marks against the use of some of these methods to estimate the costs of non-market impacts of climate change, particularly non-use values. Methods for assessing non-use values, such as contingent valuation and choice modelling have been refined significantly in recent years and are now quite widely applied both in Australia and overseas. Nevertheless, the methods remain controversial and can be quite time consuming and expensive to apply. MODELLING THE COSTS OF CLIMATE CHANGE

Equilibrium Analysis

General eqUilibrium analysis accounts for the inter-sectoral reallocation of resources that could occur as a consequence of climate change. It accounts for the effects on the inputoutput structure of the economy, effects that cannot be captured through partial equilibrium analysis. Thus, it is appropriate to use general equilibrium analysis when the impacts of climate change (or adaptation policies and measures) to be modelled are likely to simultaneously affect many sectors or markets and factor prices and incomes. The two main types of models that can be used to undertake general equilibrium analysis are input-output (10) models and Computable General Equilibrium (GCE) models. Integrated Assessment (IA) models, a generic term describing the models that attempt integrate the physical

264

Sillluiatiolls of the Effects of Climate Challge

impacts of climate change, with socio-economic effects. These often include GCE modelling. Computable General Equilibrium Models Features of CGE Models

Computable General Equilibrium (GCE) models are models of the total economy, covering all sectors of the economy and the interactions between those sectors. Essentially they simulate markets for factors of production and products across the whole economy using systems of equations specifying supply and demand behaviour across the different markets. The models are designed to examine the welfare changes (measured in terms of GDP or GNP) arising from an external 'shock' impacting on price. The shocks examined may relate to a hypothetical or actual government policy such as the introduction of a carbon or energy tax. Other shocks, such as those relating to the impacts of climate change can also be examined, provided they are price-related. Common features of GCE models include that they: determine quantities (of product and factors) and prices; focus on equilibrium resource allocation; product and factor markets are perfectly competitive; all markets clear; households (product) demand and (factor) supply functions are consistent with utility maximisation; and producer supply and demand functions are assumed to be consistent with profit maximisation., Weaknesses of CGE Models

A key strength of CGE models, already alluded to, is their

Costs of Climate Challge Mitigatioll

265

ability to model effects of policies and other external shocks on the total economy, rather than just on discrete, individual markets or sectors. This is an important consideration in the context of costing the impacts of climate change which is likely to involve simultaneous impacts across a wide number of markets and sectors. Furthermore, CGE models have now been developed at different levels of aggregation. Thus, some GCE models are essentially domestic models containing qUite significant sectoral, regional and household detail. Other GCE models are global models and tend to have little domestic disaggregation but can assess the international effects of policy shocks such as terms of trade effects. Another important characteristic of many (although not all) recent GCE models is that they are dynamic - that is, they include relationships between variables in the model at different points in time. Thus, they do not assume a static baseline. Potential limitations with CGE models have been raised, particularly in the context of their application to the climate change issue. These include: By their nature, the models can say little about the implications of non-price policies and shocks. This means that important policy responses to the impacts of climate change relating to adaptation, such as landuse planning, public information, product and building standards, and the development of new technologies and systems in response to impacts cannot effectively be modelled. It also raises questions about the ability of the models to effectively assess nonmarket impacts and 'Catastrophic events. Most GCE models do not model the equity effects of policies for different income levels. Thus, the impacts of climate change involving significant distributional issues are unlikely to be reflected well in GCE models. In response, it is important to note that these possible

266


limitations are not unique to GCE models and could equally well apply to all methods of economic analysis. Furthermore, there are potential techniques and methods for dealing for equity issues and with non-price policies. GCE Models Applied to the Climate Change Issue

The application of CGE modelling to the assessment of costs of climate change impacts has yet to be undertaken in Australia. A number of models have been developed or adapted specifically for the purpose of evaluating the economic implications of Australian and international greenhouse gas (GHG) mitigation policies. These include: MMRFGreen (Monash University), MM600+ (Econtech), GTEM (ABARE) and G-Cubed (Australian National University). These models have all assessed the economic costs but not the benefits of GHG mitigation. Pezzey and Lambie provide a comparative analysis of the technical specifications of the models. As Pezzey and Lambie have noted, GHG control is an issue that is suited to the application of GCE modelling since as it involves ".. a long time horizon, global pollution derived from a major commodity, pervasive economic effects that include impacts on trade and public finance, a case for economic instruments". Many of these characteristics apply equally to the potential impacts of climate change and adaptation to those impacts. Other key points from Pezzey and Lambie's analysis that are pertinent to the potential application of GCE models to costing the impacts of climate change include: Each model can make a valuable contribution to greenhouse policy analysis but the choice of model will depend upon the policy question of interest.


267

The models' emission reference levels, representations of technical change and substitution and demand elasticities are important influences on cost projections. The realism of policy analysis and the estimation of abatement costs using these models may be restricted by: the inability of the models to include non-price policies (for example information campaigns, exhortation and land-use planning); and the representation of the rate of technical change (all current versions of the models treat technical change as exogenous to some degree). GeE models could potentially be used in several ways to

model the impacts of climate change. These include: examining the general equilibrium impacts of a specified or assumed change in the market price of commodi ty resulting from the impacts of climate change. For example,. assume a significant increase in the price of water for domestic, industrial or agricultural users (resulting from measures taken to adapt to reduced rainfall and runoff in water supply catchments estimate for a given climate change scenario) and then trace this change through the rest of the economy; or modelling directly the general equilibrium impacts of climate change on a market or sector by drawing on the results of 'bottom-up' studies. This requires demand and supply responses for relevant industries to be built into the model. For example, 'bottom-up' studies are used to estimate the costs of adapting to a reduction in available water supplies for a given climate change scenario. These costs are then traced through the rest of the economy.

268


As indicated by an earlier point made in relation to Pezzey and Lambie's analysis, the choice of model and the way in which it is used will depend very much upon the climate change impact to be assessed or the adaptation policies or measures of interest. Internati9nally, a number of models have been developed to assess the costs of climate change impacts at regional or global levels, usually within an integrated assessment framework. As previously noted, some of these models have been developed or adapted to assess the costs and benefits of climate change mitigation within a costbenefit framework. Their objective is to assess at what point the marginal benefits of climate change mitigation policies (Le. reduced costs of climate change impacts), are outweighed by the marginal costs of the mitigation (Le. emission abatement policies or targets) and thereby determine an optimal level of emission reduction. Critics of some of the models have pointed to the models' treatment of non-market impacts, distributional effects and catastrophic events. Integrated Assessment (lA)

Integrated assessment (IA) seeks to combine socioeconomic and biophysical assessments of climate change. It is an: " ... interdisciplinary process tlwt combines, interprets and communicates knowledge from diverse scientific disciplines in an effort to investigate and understand causal relationships within and between complicated systems" Ahmad and Warrick.

Integrated assessment can employ a range of methods including scenario analysis, qualitative assessment and computer modelling. Many integrated assessment models of global climate -'change have been developed over the past decade or so, most of which have a focus on mitigation responses and costs. Many of these models have


269

taken a 'top-down' approach, assessing damages at a regional or global level based on a global mean temperature change associated with a doubling of atmospheric CO 2 concentrations. Given this level of aggregation and widely different assumptions used in terms of the nature of associated impacts, it is not surprising to find that these studies have produced a very wide range of results. More recent 'bottom-up' IA models have sought to capture the individual direct effects of climate change at the local or regional level. As Mendelsohn et al. note however, "Although these models have done a good job of capturing spatial and sectoral detail, they oftell cOlltain so much detail that they are difficult to interpret. Further, they often lack sound damage estimates because they do not seek to estimate welfare effects and because they fail to accoullt for adaptation (thus they are) far from providing clear alld careflll damage estimates".

The ~hallenge therefore is to make use of the spatial and sectoral detail of 'bottomup' models, while ensuring that: inter-regional and economy-wide effects and feedbacks are addressed; feedbacks arising from policy responses and adaptation measures are fully captured; and impacts are assessed on the basis of realistic scenarios of changes to future environmental, social-economic and land use conditions that are unrelated to climate change. The results must then be presented in way that is useful for decision-making purposes. In Australia, an integrated assessment of climate change in the Cairns and Great Barrier Reef (CGBR) is currently the subject of a scoping study for the AGO. lie

270


proposed IA is to comprise a number of elements including: development of climate change projections specific to the region; development of regional models of land use and socioeconomic change; development of spatial vulnerability and hazard maps; integrated assessment models for the key sectors in the region, incorporating models and methodologies from different disciplines wit:l)in a unified systems framework; c;:ost-benefit analysis of adaptation options; and expanded monitoring to reduce knowledge gaps. Many of the important elements of effective IA identified earlier - a strong regional and sectoral focus, projections of environmental, socio-economic and land use changes, and incorporation of feedbacks including from adaptation - appear to have been included in the proposed CGBR region study, although it is unclear how inter regional and economy wide effects are to be addressed.

Bibliography Alverson, Keith D. and Thomas Pedersen, "Environmental Variability and Climate Change", {Stockholm]: International

Geosphere-Biosphere Programme, 2001. Balifto, Beatriz M., Michael J.R. Fasham, and Margaret C. Bowles, eds., "Ocean Biogeochemistry and Global Change: JGOFS Research Highlights, 1998-2000", Stockholm, Sweden:

International Geosphere-Biosphere Programme, 2001. Edgerton, Lynne T., "The Rising Tide: Global Warming and World Sea Levels", Washington, D.C.: Island Press, 1991. Gates, David Murray, Climate Change and its Biological Consequences. Sunderland, MA: Sinauer Associates, 1993. International Geosphere-Biosphere Programme, A Study of Global Change. Stockholm, Sweden: IGBP Secretariat, Royal Swedish Academy of Sciences, 1998. Knox, Joseph B. and Ann Foley Scheuring, eds., "Global Climate Change and California: Potential Impacts and Responses. Berkeley, CA: University of California Press, 1991. Minger, Terrell J., "Greenhouse Glasnost: The Crisis of Global Warming: Essays", New York: Ecco Press; [Salt Lake City, Utah]: Institute for Resource Management, 1990. Mortensen, Lynn L., ed., Global Change Education Resource Guide, [Boulder, CO]: University Corporation for Atmospheric Research, 1996. Nunn, Patrick D., Environmental Change in the PacifiC Basin: Chronologies, Causes, Consequences, Chichester, West Sussex, England; New York: Wiley, 1999.

272


Peters, Robert L. and Thomas E. Lovejoy, eds., Global Wanning and Biological Diversity. New Haven, CT: Yale University Press, 1992 Revkin, Andrew, Global Wanning Understanding the Forecast, New York: Abbeville Press, 1992. Somerville, Richard, The Forgiving Air: Understanding Environmental Change, Berkeley, CA: University of California Press, 1996. Thompson, Russell D. and Allen Perry, eds., Applied Climatology: Principles and Practice. London; New York: Routledge, 1997. Veroustraete, F., et al., eds., Vegetation, Modelling and Climatic . Change Effects, The Hague, The Netherlands: SPB Academic Pub., 1994.

Index Aerosol forcing 63 Agricultural systems analysis 47 Atlantic deep water 71 Atmospheric CO2 concentration 25 Calcium carbonate sediments 78 Carbonate deposition 75 Carbon-cycle modelling 45 Clean water act 116

Forest fires 93 General Circulation Models (GCMs) 1 Global temperature change 23 GreenHouse Gas (GHG) 236 Gross Primary Production (GPP) 2

Hydrological cycle 51

Climate models 50 Computable General Equilibrium (GCE) 263 Contingent Valuation Method (CVM) 255 Cost-Benefit Analysis (CBA) 258 Crop impact analysis 39 Cultivated land 92 Deep water formation 64 Dynamic changes 129 Ecological goods 200 ~cological succession 134 Euphotic zone 74 Experimental Lakes Area (ELA) 155 Faecal pellet bomb 102 Forcings-volcanic plumes 104

Integrated Assessment (IA) 263 Intergovernmental Panel on Climate Change (IPCC) 236 International Biological Programme (IBP) 127 Land-biota soil reservoir 102 Land surface processes 63 Local ecosystem 86 Mineral nutrients 100 Modelling programmes 51 National Pollutant Discharge Elimination System (NPDES) "116 Nitrogen fertilisers 31 Oak Ridge National Laboratory

274


(ORNL) 23 Oceanic carbon pool 70 Photosynthetically Active Radiation (PAR) 109 Production cost technique 250 Reducing Acidification In Norway (RAIN) 157 Regional climatic change 47 Soil carbon mass 93 Stratospheric processes 64

Terrestrial Ecosystem Model (TEM) 1 Third Assessment Report (TAR) 236 Tropical evergreen forests 92 Volcanic aerosols 54 Volcanic eruption 104 Watershed Manipulation Project (WMP) 169 Wildlife conservation 140 Willingness To Accept (WTA) 239

Simulations Of The Effects Of The Climate Change

Climate: Causes and Effects of Climate Change

Climate: Causes and Effects of Climate Change (Our Fragile Planet)

The Economics Of Climate Change

The Economics of Climate Change

The Economics of Climate Change

Causes Of Climate Change

Politics of Climate Change

Politics of Climate Change

Climate Change: Causes, Effects, and Solutions

Meeting the Climate Challenge: Recommendations of the Climate Change Taskforce

Climate Change: Causes, Effects, and Solutions

The Ethics of Global Climate Change

The Benefits Of Climate Change Policies

Urbanism in the Age of Climate Change

Overheated: The Human Cost of Climate Change

Climate and Climate Change

Adapting to the Impacts of Climate Change (America's Climate Choices)

Limiting the Magnitude of Future Climate Change (America's Climate Choices)

The Economics of Climate Change Policies: Macroeconomic Effects, Structural Adjustments and Technological Change (Sustainability and Innovation)

Limiting the Magnitude of Future Climate Change (America's Climate Choices)

Advancing the Science of Climate Change (America's Climate Choices)

The Economics of Climate Change Policies: Macroeconomic Effects, Structural Adjustments and Technological Change

Adapting to the Impacts of Climate Change (America's Climate Choices)

Ecological Impacts of Climate Change

Dictionary of Global Climate Change

Climate and Climate Change (The Living Earth)

Climate Change

Climate change

Climate Change

Climate Change

Simulations Of The Effects Of The Climate Change

Climate: Causes and Effects of Climate Change

Climate: Causes and Effects of Climate Change (Our Fragile Planet)

The Economics Of Climate Change

The Economics of Climate Change

The Economics of Climate Change

Causes Of Climate Change

Politics of Climate Change

Politics of Climate Change

Climate Change: Causes, Effects, and Solutions

Meeting the Climate Challenge: Recommendations of the Climate Change Taskforce

Climate Change: Causes, Effects, and Solutions

The Ethics of Global Climate Change

The Benefits Of Climate Change Policies

Urbanism in the Age of Climate Change

Overheated: The Human Cost of Climate Change

Climate and Climate Change

Adapting to the Impacts of Climate Change (America's Climate Choices)

Limiting the Magnitude of Future Climate Change (America's Climate Choices)

The Economics of Climate Change Policies: Macroeconomic Effects, Structural Adjustments and Technological Change (Sustainability and Innovation)

Limiting the Magnitude of Future Climate Change (America's Climate Choices)

Advancing the Science of Climate Change (America's Climate Choices)

The Economics of Climate Change Policies: Macroeconomic Effects, Structural Adjustments and Technological Change

Adapting to the Impacts of Climate Change (America's Climate Choices)

Ecological Impacts of Climate Change

Dictionary of Global Climate Change

Climate and Climate Change (The Living Earth)

Climate Change

Climate change

Climate Change

Climate Change

Recommend Documents