Combating Acid Deposition and Climate Change: Priorities for Asia

Abstract

The article addresses two interactions relevant to acid rain and global warming. First are interactions between sulfur and carbon emissions in producing important impacts, e.g., agricultural impacts in Asia. Second are behavioral interactions, i.e., rational responses to policies targeting one problem that make the other more difficult to solve. Initial calculations for the case of no new policies to limit sulfur or carbon emissions suggest that the cooling effect of sulfate aerosols would offset global warming from carbon dioxide, while carbon dioxide fertilization would more than offset crop losses due to acidification. The net result for the world as a whole in 2050 would be slight increases in agricultural production and GDP, and a slight decrease in prices - hardly a reason to limit carbon and sulfur. Two weaknesses of such global calculations are, first, that reasonable changes in assumptions about carbon dioxide fertilization plus the inclusion of agricultural impacts after 2050 could tip the balance slightly in the other direction, and, second, that they ignore regional differences and politics. The centrally planned countries of Asia are unlikely to tolerate the acidification they would suffer in the absence of new sulfur control policies. Indeed, China has already begun sulfur reductions. However, sulfur reductions without carbon reductions risk removing much of the potential sulfate aerosol shade that would otherwise tend to limit global warming and, perversely, entrenching the importance of coal. To explore the possibility of reducing both sulfur emissions and carbon emissions, the article concludes with an example focused not on one side or the other of the carbon-sulfur equation but on the technologies that are common to both.