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The Debate Over Evidence
The debate over whether or not the atmosphere is warming has been quite intense
since the late 1990s. Satellite records, with a more limited period than surface temperatures,
suggested that the rapid warming in since 1970 might be artificial, but a subsequent
re-calibration of the temperature data eliminated the differences in the two records.
The "Summary for Policy Makers" of the Intergovernmental Panel on Climate Change Fourth Assessment Report issued in February 2007 produced a strongly worded statement about the role of humans in climate change:
"Changes in climate are now affecting physical and biological sysems on every continent. Effects on human systems, although more difficult to discern due to adaptation and non-climatic drivers, are emerging. Over 99% of obeserved changes in systems and sectors are consisten with regional temperature trends. Many of the changes are now attributed to temperature increase caused by anthropogenic greenhouse gas emissions."