The climate has changed. Human beings are responsible. And the climate will change further as energy use, agriculture, deforestation, and industrial production continue to increase. In the course of this century it could get up to 6 °C warmer, with more heat waves, droughts, floods, and storms. As a result a wide range of impacts can be expected. Food production and water availability will diminish. Nature will suffer, with a large percentage of species threatened with extinction. New health problems will arise. Coastal areas and river deltas will face more floods. The overall effect of this will be devastating for poor countries, undermining their efforts to eradicate poverty. But even rich countries will see the costs of these impacts rise to significant levels.