Note: This is the 1997 edition of UNEP's Global Environment Outlook. If you are interested in more recent information, please see the 2000 and 2002 editions.

United Nations Environment Programme (UNEP)
Global  Environment Outlook-1 - The Web version

Chapter 4: Looking to the Future

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Climate Change and Acidification

Interactions Between Climate Change and Acidification

To consider the interaction of climate change and acidification, the IMAGE 2, RAINS Europe,  and RAINS Asia models were used, focusing on Europe and Asia (Posch et al.,1996).

Emissions of acidifying pollutants, especially sulphur dioxide, lead to the accumulation of particles in the upper atmosphere, which partly masks the climate change caused by greenhouse gases. If global emissions of sulphur dioxide increase in parallel with the use of fossil fuels in developing countries, then the mass of those particles in the atmosphere will also increase, moderating this warming trend. (See Figure 4.8.)

Nevertheless, global average temperature is still projected to increase significantly even if sulphur dioxide emissions grow uncontrollably (which would have separate, adverse effects on the environment), and important shifts in global weather systems could occur. If emissions of acidifying gases were reduced while those of greenhouse gases were not, decreasing sulphur dioxide particle concentrations would "unmask" the warming caused by greenhouse gases, leading to even greater increases in global temperature affecting both industrial and developing nations. This underscores the importance of studying the interactions among environmental problems rather than just looking at, for example, acidification and climate change in isolation.

Trends in emissions of sulphur dioxide in two regions for two different sets of assumptions (no controls and partial controls) are depicted in Figure 4.9.

Land areas that could be affected by both acidification and climate change in Europe and Asia in 2015 and 2050 according to the model simulations are shown in Figure 4.10 a, b, c, d, e, and f. It is predicted that 12.5 per cent of Europe and 7.3 per cent of Asia are liable to be affected by both problems in the year 2050 (Alcamo et al.,1995; Posch et al., 1996).

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