The most recent IPCC report states:
For the next two decades a warming of about 0.2 °C per decade is projected for a range of emission scenarios. Even if the concentrations of all greenhouse gases and aerosols had been kept constant at year 2000 levels, a further warming of about 1 °C per decade would be expected.
Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 2oth century.
In the figure below, are predicted global average surface temperature changes for several emission scenarios, relative to 1980 to 1999 averages). The shading is the uncertainty range (one standard deviation). The orange line is the prediction assuming that emissions are held constant at 2000 levels. The grey bars on the right indicate the likely range for all scenarios studied. See the (Summary for Policy Makers)

for an explanation of the various scenarios. The range of possible global temperature increase by the year 2100 is between 1.1 °C and 6.4 °C (2 °F and 11.5 °F).

Other IPCC observations:
Warming will reduce land and ocean uptake of atmospheric carbon dioxide, which will increase the fraction of carbon dioxide remaining in the atmosphere.
The projected sea level rise for the end of the 21st century is between 0.18 and 0.59 m (7 and 23 inches), with a mid range of about 0.39 m (15 inches). These predictions are for sea level rise due to expansion of warming seas; the predictions do not include the contribution from melting snowpack and ice over land surfaces.
Increasing carbon dioxide absorption by oceans will lead to increasing acidification of seawater.
There is now higher confidence in projected patterns of warming and other regional scale features, including changes in wind patterns, precipitation, and some aspects of extremes and of ice. The figure below provides projections of regional surface temperatures for the period of 2020-2029 and 2090-2099. The predictions are based on an average of three scenarios and several warming models. The panel on the left provides an indication of the uncertainties associated with the predictions for the various models for each of the scenarios.

Snow cover will continue to contract and increases in thaw depth are projected for most permafrost regions. Sea ice is projected to shrink for both the Arctic and Anarctic.
It is very likely (>90% confidence) that hot extremes, heat waves, and heavy precipitation will become more frequent.
Future tropical cyclones (typhoons and hurricanes) will become more intense.
Both past and future carbon dioxide emissions will continue to contribute to warming and sea level rise for more than a millennium, due to the timescales required for removal of the gas from the atmosphere.

http://zfacts.com/p/811.html | 01/18/12 07:18 GMT
Modified: Mon, 07 May 2007 01:52:11 GMT