Humans are “very likely” causing global warming

“Friday, 2 February 2007 may go down in history as the day when the question mark was removed from the question of whether climate change has anything to do with human activities” — Achim Steiner, Executive Director of the United Nations Environment Program (UNEP) [1]

In an important report published yesterday in Paris, France the Intergovernmental Panel on Climate Change (IPCC) declared that human are “very likely” a cause of global warming. While this isn’t exactly breaking news, what is significant is that in a 2001 report the IPCC said humans are “likely” a cause of global warming. In more concsete terms, the IPCC definition for likely is a 66-90% probability. This means the probabilty of a human effect is now greater than 90%. [2]

Another interesting paragraph of the IPCC Executive Summary read the following:
“The observed widespread warming of the atmosphere and ocean, together with ice mass loss, support the conclusion that it is extremely unlikely that global climate change of the past fifty years can be explained without external forcing, and very likely that it is not due to known natural causes alone.” [3]

Other highlights from the IPCC report:
1. By the end of the century, temperatures will probably rise 1.8-4C (3.2-7.2F) and could possible rise between 1.1-6.4C (2-11.5F)
2. Sea level likely to go up by 28-43 cm (11-16 inches)
3. By the second half of the century, Arctic sea ice will disappear entirely during the summer months.
4. Eleven of the last 12 years are some of the warmest on record
5. Changes in weather patterns will lead to longer and more intense droughts, heatwaves, and tropical storms.

The IPCC will release a full report later this year and will release reports on how to adapt to climate change and suggestions towards reducing greenhouse gases. Stay tuned for more updates.

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Posted by Tim Roth, author of the political blog Think Anew and Act Anew

Sources:
1. “Analysis: Through the climate window” by Richard Black, BBC News
2. “Humans blamed for climate change” by Richard Black, BBC News
3. IPCC report (PDF), released on February 2, 2007