The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) stated for the first time that scientific evidence of human-induced global warming is unequivocal, and that the latest predictions are much worse than previous estimates (Houghton et al., 2001). The last 100 years have been the warmest on record. Furthermore, warming during the last 50 years has a clear human signature. Global temperatures will increase by 1.4°C to 5.8°C by 2100; sea levels are rising and are expected to increase by 14 to 88 cm by 2100, flooding low-lying areas and displacing hundreds of millions people. Rainfall patterns are changing, El Niño events are increasing in frequency and intensity, Arctic ice is thinning, and tropical mountain glaciers are retreating.
The consequences of these changes are also dire according to this report. Agricultural productivity in Africa and Latin America could decrease by as much as 30% during this century. Severe droughts will occur in Southern Africa and Southeast Asia. Wetter climates and more floods are predicted for parts of East Africa and Latin America. And more smoke and haze problems are predicted for Southeast Asia and Central America. Higher worldwide food prices are likely to result, negatively affecting the urban poor.
Major changes are also predicted in critical ecosystems, particularly coral reefs and tropical forests. The geographic spread of malaria and increased crop pest and disease pressure in wetter climates are also predicted. The IPCC reported global economic losses of around $40 billion due to existing global warming in 1999, of which 25% occurred in the tropics (Houghton et al., 2001). The capacity of people to adapt to these global changes is correlated with poverty level. Countries with the least diversified agriculture, forestry, and fisheries will suffer the most. Africa is considered to be the region most vulnerable to global warming (Houghton et al., 2001). A major discrepancy exists between developed and developing countries in terms of human-induced global warming and who pays for the consequences. About 75% of anthropogenic CO2 emissions are due to fossil fuel burning, mainly from the
North, while the remaining 25% is due to changes in tropical land use, especially deforestation in the South. While contributing the least to global warming, the tropical countries will suffer the most from it.
The following section includes a discussion of some key research issues identified by the Consultative Group on International Agricultural Research (CGIAR) Inter-Center Working Group on Climate Change (2001). The tropics will face a special challenge in coping with climate change. Issues discussed are arranged in terms of impact, adaptation, and mitigation of climate change.
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