Elements of change
Most models predict that future climate change could include:
The global average surface air temperature is estimated to increase between 1.4°C and 5.8°C by 2100. Climate models cannot yet provide a detailed picture of regional climate change, but it is likely that nearly all land areas, particularly those at high latitudes in the winter season, will warm more rapidly than the global average. Most notable is the warming in the northern regions of North America, and northern and central Asia. This can be seen in the image to the right. In contrast, the warming is Less than the expected global mean over South and Southeast Asia in summer and southern South America in winter. The surface temperature is likely to rise least in the North Atlantic and the circumpolar Southern Ocean.
Globally, it is expected that water vapour and precipitation will increase along with the warming. However this increase in precipitation will not be evenly spread across the globe. It is expected that precipitation will increase over northern middle and high latitudes and Antarctica in winter. It is also expected that more precipitation will fall in larger single events rather than spread over numerous events. At low latitudes both regional increases and decreases of rainfall over land areas are expected. Larger year-to-year variations are likely over those areas where the mean precipitation is predicted to increase. The graph shows projected changes to precipitation late in the century under a high emission scenario.
At high latitudes in the Northern Hemisphere, snow cover and sea-ice extent will continue to decrease. Glaciers and ice caps are projected to continue their widespread retreat. Over Greenland, the ice sheet is expected to lose mass as a result of ice melt runoff and iceberg calving. Only the Antarctic ice sheet is likely to gain in mass because of greater precipitation.
Global mean sea level is projected to rise between 0.09 and 0.88 m above the 1990 level by 2100. This rise is due primarily to thermal expansion of the warmer oceans combined with melting of glaciers and ice sheets. Rising sea levels are expected to have severe effects on many low-lying areas, forcing populations to move inland to higher levels.
Even if CO2 concentrations are stabilized by the year 2100, the global mean temperature and sea level are projected to continue to increase. This continued increase is due to the slow thermal response of the oceans.
[Further information] can be found in the IPCC’s Frequently asked questions, How are temperatures on Earth Changing?, How is precipitation changing?, Is the Amount of Snow and Ice on the Earth Decreasing? and Is sea Level rising?
[More in depth information] on expected impacts and elements of climate change can be found in the IPCC Fourth Assessment Report, working group 1, specifically chapter 10 and 11 on climate change projections.
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