Abrupt Climate Change: A Report

The U.S. Climate Change Science Program (CCSP), headed by the USGS (U.S. Geologic Service) has just released it latest Synthesis and Analysis Product (SAP) “focus[ing] on abrupt climate change events where key aspects of the climate system change faster than the responsible forcings would suggest and/or faster than society can respond to those changes.”

The short view is:

• Rapid and sustained September arctic sea ice loss is likely in the 21st century.
• The southwestern United States may be beginning an abrupt period of increased drought.
• It is very likely that the northward flow of warm water in the upper layers of the Atlantic Ocean, which has an important impact on the global climate system, will decrease by approximately 25–30 percent. However, it is very unlikely that this circulation will collapse or that the weakening will occur abruptly during the 21st century and beyond.
• An abrupt change in sea level is possible, but predictions are highly uncertain due to shortcomings in existing climate models.
• There is unlikely to be an abrupt release of methane, a powerful greenhouse gas, to the atmosphere from deposits in the earth. However, it is very likely that the pace of methane emissions will increase.

You can read the final report, here, [scroll down to see the chapters listed separately.]

The Executive Summary may be the best place to begin.

“This report reflects the significant progress in understanding abrupt climate change that has been made since the report by the National Research Council in 2002 on this topic, and this report provides considerably greater detail and insight on these issues than did the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). New paleoclimatic reconstructions have been developed that provide greater understanding of patterns and mechanisms of past abrupt climate change in the ocean and on land, and new observations are further revealing unanticipated rapid dynamic changes of moderns glaciers, ice sheets, and ice shelves as well as processes that are contributing to these changes. This report reviews this progress.”

Or, you may prefer the colorful, four page brochure, suitable for printing and handing out at coffee houses….

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