Potential increase in global average surface temperatures resulting from enhancement of the greenhouse effect by air pollution .
In 2001 the U.N. Intergovernmental Panel on Climate Change estimated that by 2100 global average surface temperatures would increase by 2.5 to 10.4 °F (1.4 to 5.8 °C), depending on a range of scenarios for greenhouse gas emissions. Many scientists predict that such an increase would cause polar ice caps and mountain glaciers to melt rapidly, significantly raising the levels of coastal waters, and would produce new patterns and extremes of drought and rainfall, seriously disrupting food production in certain regions. Other scientists maintain that such predictions are overstated. The 1992 Earth Summit and the 1997 conference of the UN Framework Convention on Climate Change attempted to address the issue of global warming, but in both cases the cause was hindered by conflicting national economic agendas and disputes between rich and poor nations over the cost and consequences of reducing emissions of greenhouse gases.