You’re getting warmer
The Intergovernmental Panel on Climate Change is finalizing its “Climate Change 2007” report, which shows the findings of more than 2,500 scientific experts from about 130 countries during six-plus years of research. The final report will be issued in November in Spain. The full draft is found at www.ipcc.ch. Here are some highlights from its “robust findings” section:
• Fossil fuel use, agriculture and land use have been the dominant cause of increases in greenhouse gases over the last 250 years.
• The sustained rate of increase in radiative forcing from CO2, CH4 and N2O over the past 40 years is larger than at any time during at least the past 2,000 years.
• It is extremely likely that human activities have exerted a substantial net warming influence on climate since 1750.
• Global mean surface temperatures continue to rise. Eleven of the last 12 years rank among the 12 warmest years on record since 1850.
• The amount of ice on the Earth is decreasing. There has been widespread retreat of mountain glaciers since the end of the 19th century. The rate of mass loss from glaciers and the Greenland Ice Sheet is increasing.
• The global temperature (or heat content) of the oceans has increased since 1955.
• Thermal expansion of the ocean and loss of mass from glaciers and ice caps made substantial contributions to the observed sea level rise.
• It is very unlikely that the Earth would naturally enter another ice age for at least 30,000 years.
• It is extremely unlikely (less than 5 percent) that the global pattern of warming during the past half century can be explained without external forcing, and very unlikely that it is due to known natural external causes alone.
• Future warming would tend to reduce the capacity of the Earth system (land and ocean) to absorb anthropogenic CO2. As a result, an increasingly large fraction of anthropogenic CO2 would stay in the atmosphere under a warmer climate.
• Projected warming due to emission of greenhouse gases during the 21st century will continue to contribute to sea level rise for many centuries.