ABSTRACT
Human-induced climate change is only an issue if it is large enough and rapid enough to create real problems for natural ecosystems and for human societies. The chapter describes projected changes in climate based on both these special report on emissions scenarios and on some 'stabilisation scenarios' that assume policies leading to a levelling off of carbon dioxide concentrations at various values. Warming in continental interiors and in the high latitudes of the northern hemisphere is expected to be greatest with less expected over the oceans and windward coastlines. Global average precipitation and evaporation are projected to increase by about 1 to 9% by 2100, depending on which scenario and climate model is used. Sea-level rise is obviously important, given that a rapidly increasing number of people live in low-lying coastal areas. The problem for climate change projections is therefore to capture the possibility and the probability of, and risk from, Large-scale abrupt changes.
