The Impacts of Climate Change, Carbon Dioxide, and Sulfur Deposit ion on Agricultural Supply
8. Discussion and Conclusions
World population is espected t o alillost double between 1990 and 2050 from 5 t o about 10 billion people, which in turn will necessitate major increases in the level of economic activities, in energy consumption, and in food produc- tion. The analysis presented starts from economic projections t h a t stipulate a more t h a n 10-fold increase of GDP in developing regions between 1990 and the middle of the nest century. Undoubtedly, such dramatic demographic and economic changes will put heavy demands on resources and will require the application of more efficient and environmentally benign technologies.
T h e costs of such enviroilmentally benign technologies, however, are con- siderable. T h e projected differences in energy investments between abate- ment scenarios (both MOM and MIS) and the coal-intensive HER scenario amount t o about 0.5% of global C:DP (US$ value), and more than 1% of G D P in East Asia (CPA region). It is justified, therefore, t o carefully ana- lyze the regional and global consequences of a failure t o implement emission abatement in the energy sector.
Wheil looking only a t the projected climate and C 0 2 effects of the three alternative energy and emission scenarios, conditions in the high-emissions scenario are more beneficial t o agriculture than those in the abatement sce- narios. This perhaps counterintuitive finding derives from the projected conditions, namely, t h a t the high-emissions scenario produces the highest C 0 2 level ( a positive effect) and causes the least warming ( a negative im- pact) of the three cases analyzed. Thus, global impacts on agriculture alone, and on the basis of the single pollutant taken into account here (i.e., S O z ) , do not seem t o provide sufficient economic justification for abatement.
However, unlike the deba.te on cli~llate change impacts where the regions mainly responsible for the increa.se in atmosplleric C 0 2 concentration may be different from those most affected by it, the damage caused by air pollu- tion stays more closely withill the region of origin, a t least when analyzing the effects in terms of broa.der world regions. Hence, from a regional per- spective, abatement appears t o be foremost in the interest of t h e polluters themselves. Thus, emissioil a,batenlent in terms of agricultural impacts is a regional issue much more than a globa,l one. Furthermore, high levels of SO2 emissions pose a llumber of enviroilmelltal risks not included in this anal- ysis. T h e detrimental inlpacts of a,irborile chemicals include human health effects, acidification of soils and wa.ter bodies, forest dieback, and damage t o buildings and infrastructure. Whereas the cost of abatement measures is determined by rather well-specified investment requirements, the damage caused by SO2 and related polluta.nts is complex, of multiple forms, and widespread.
Appendix. Aggrega.tion of BLS couiltsy modules into world regions.
Economic
group Region BLS component."
Developed NAM Canada, USA
WEUSODE Austria, EC-9, Rest of the worldb EEUSFSU Eastern Europe & USSR
P A 0 Australia, Japan, New Zealand Developing AFR Kenya, Nigeria,
Africa Oil Exporters,
Africa medium income/calorie exporters, Africa medium income/calorie importers, Africa low income/calorie exporters, Africa low income/calorie importers LAM Argentina, Brazil, Mexico,
Latin Ainerica high income/calorie exporters, Latin America high income/calorie importers, Latin America inediuin income
WAS Egypt, Turkey,
Near East Asia oil exporters, Near East Asia medium-low income SAS India, Paltistan,
Asia low income
CPA China,
Far East Asia high-medium income/calorie importers PAS Indonesia, Thailand,
Far East Asia high-medium income/calorie exporters
"For details of country grouping in t,he BLS, see Fischer et nl. (1988).
b ~ h e main characteristics of the Rest of the world region derive from developed countries mainly in Europe; the region also inclndes some developed and developing countries in other parts of the world.
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