New abrupt climate change report says greater sea level rise and more arid U.S. Southwest likely


The United States faces the potential for abrupt climate change in the 21st century that could pose clear risks to society in terms of our ability to adapt, concludes a recently released U.S. Climate Change Science Program synthesis report. The report’s conclusions suggest the need for a U.S. climate change adaptation policy to prepare for impacts of rising sea level on coastlines, and for the prospect of a long-term shift to a more arid climate in the Southwest with the potential for periods of prolonged drought.

The Abrupt Climate Change report (CCSP Synthesis and Assessment Product 3.4), one of 21 such reports initiated in 2003, was more than a year overdue, having originally been scheduled to be issued by September 2007.  Thus the report has been yet another victim of the Bush administration’s and the CCSP leadership’s lack of timeliness in keeping to publication schedules (except when under a court order).

That being said, however, the authors had the benefit of significant recent advances in observations and research on accelerated ice melt in the polar regions since the work that was used in the 2007 assessment by the Intergovernmental Panel on Climate Change—and it now appears that the IPCC may have significantly lowballed the likely rate and amount of global sea level rise in the 21st century.

Now that the report has been published, something should follow from the work of the scientists who drafted it.  They have provided an assessment of the current state of scientific understanding of key issues bearing on the potential for abrupt climate change. But, despite the CCSP’s description of these synthesis reports as “decision support resources,” they are not really designed to meet the needs of decisionmakers at the national level and in states and local communities for planning and technical assistance in coming up with real-world resilience-building responses to the likely acceleration of harmful climate change impacts discussed in the report. Policy planning and technical assistance is the currently missing link in connecting science with action.

Juliet Eilperin had a good article about the report on page 2 of the (December 25) Washington Post.  A few excerpts: 

Faster Climate Change Feared
New Report Points to Accelerated Melting, Longer Drought

The United States faces the possibility of much more rapid climate change by the end of the century than previous studies have suggested, according to a new report led by the U.S. Geological Survey.

The survey—which was commissioned by the U.S. Climate Change Science Program and issued this month—expands on the 2007 findings of the United Nations Intergovernment Panel on Climate Change. Looking at factors such as rapid sea ice loss in the Arctic and prolonged drought in the Southwest, the new assessment suggests that earlier projections may have underestimated the climatic shifts that could take place by 2100….

On potentially accelerated and greater sea level rise:

[T]he report projects an amount of potential sea level rise during that period that may be greater than what other researchers have anticipated, as well as a shift to a more arid climate pattern in the Southwest by mid-century….

In one of the report’s most worrisome findings, the agency estimates that in light of recent ice sheet melting, global sea level rise could be as much as four feet by 2100. The IPCC had projected a sea level rise of no more than 1.5 feet by that time, but satellite data over the past two years show the world’s major ice sheets are melting much more rapidly than previously thought. The Antarctic and Greenland ice sheets are now losing an average of 48 cubic miles of ice a year, equivalent to twice the amount of ice that exists in the Alps.

On the potential for prolonged drought in the U.S. Southwest:

Scientists also looked at the prospect of prolonged drought over the next 100 years. They said it is impossible to determine yet whether human activity is responsible for the drought the Southwestern United States has experienced over the past decade, but every indication suggests the region will become consistently drier in the next several decades. Richard Seager, a senior research scientist at Columbia University’s Lamont-Doherty Earth Observatory, said that nearly all of the 24 computer models the group surveyed project the same climatic conditions for the North American Southwest, which includes Mexico.

“If the models are correct, it will transition in the coming years and decades to a more arid climate, and that transition is already underway,” Seager said, adding that such conditions would probably include prolonged droughts lasting more than a decade.

On the need for preparedness:

[Tom] Armstrong [of the U.S. Geological Survey] said the need for “downscaled models” is one of the challenges facing the federal government, along with better coordination among agencies on the issue of climate change. When it comes to abrupt climate shifts, he said, “We need to be prepared to deal with it in terms of policymaking, keeping in mind it’s a low-probability, high-risk scenario. That said, there are really no policies in place to deal with abrupt climate change.”


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