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December 19, 2008
U.S. Could Experience Impacts of Climate Change Sooner Than Expected
The American Geophysical Union, meeting this week in San Francisco for their annual conference, released a report discussing the potential for abrupt climate change and the likely impacts it would have on the United States. The study, based on the latest scientific data and observations, updates the research of recent reports from key agencies and institutions, including the 2007 assessment from the Intergovernmental Panel on Climate Change (IPCC). Many earlier projections of the impacts of climate change have been conservative, the report concludes, such as retreating glaciers, decaying ice sheets, and loss of Arctic sea ice. On the other hand, some potential impacts may not pose as immediate a threat as previously thought, including the rapid release of methane, a much more potent greenhouse gas than CO2, or an imminent shift in the ocean current known as the Thermohaline that helps keep Europe warm (a reason why “climate change” is often a better term than “global warming” since the rise in average global temperature could potentially make some regions, like northern Europe, much colder).
Key concerns in the report are the dramatic and unexpected acceleration of sea ice melt, rising sea levels, and the potential for a permanent state of drought in the American Southwest.
What appears both more certain and immediate are rapid changes to the Greenland and West Antarctic ice sheets, diminishing sea ice, and changes to the hydrological patterns over North America and the global subtropics. All of which will persist and get worse with continuing global warming.
Peter Clark, an Oregon State professor of geosciences, says,
Our report finds that drying is likely to extend poleward into the American West, increasing the likelihood of severe and persistent drought there in the future. If the models are accurate, it appears this has already begun. The possibility that the Southwest may be entering a permanent drought state is not yet widely appreciated.”
Climate change is a recurring pattern in Earth’s history, usually occurring slowly over the course of hundreds or thousands of years. There have been times, however, when dramatic shifts in climate have happened abruptly, within decades. Which is of particular concern for human society.
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The “overarching” recommendation from the report is the need for a sustained commitment to monitor these climate forces that have triggered sudden climate change in the past and could therefore do so again. Better observing systems are needed, better forecasting of droughts should be developed, there should be a more comprehensive understanding of the AMOC circulation pattern, and methane levels should be systematically monitored.
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