Published by Cambridge University Press, the book builds upon scientific findings presented at the "Avoiding Dangerous Climate Change" conference held in Exeter, England, in February last year. The conference was sponsored by the United Kingdom Department of Environment, Food and Rural Affairs.
The conference brought together more than 200 scientists and political leaders from 30 nations. Major themes included key vulnerabilities of the climate system and critical thresholds, socio-economic effects, and technologies to limit greenhouse-gas emissions.
Based on his talk at the conference, Schlesinger contributed a book chapter titled "Assessing the Risk of a Collapse of the Atlantic Thermohaline Circulation."
Higher temperatures caused by global warming could add fresh water to the northern North Atlantic Ocean by increasing the precipitation and by melting nearby sea ice, mountain glaciers and the Greenland ice sheet, Schlesinger said. This influx of fresh water could reduce the surface salinity and density, leading to a shutdown of the thermohaline circulation.
"We have evidence dating back to 1965 that shows a drop in salinity around the North Atlantic," Schlesinger said. "So far, the salinity change is small, but we could be standing at the brink of an abrupt and irreversible climate change."
Among the talking points Schlesinger will cover at the news conferences:
"This movement carries a tremendous amount of heat northward, and plays a vital role in maintaining the current climate," Schlesinger said. "If the thermohaline circulation shut down, the southern hemisphere would become warmer and the northern hemisphere would become colder. The heavily populated regions of eastern North America and western Europe would experience a significant shift in climate."
Two major factors affect the range of possible future temperature increases: Scientists don't know precisely how sensitive the climate system will be to future emissions; and they don't know exactly how much humankind will emit. People can only control one of the factors. By reducing emissions, the amount of future warming and associated impacts can be reduced.
"Recent work by five independent research teams has shown that climate sensitivity could be larger than the 4.5 degrees Celsius upper bound published by the Intergovernmental Panel on Climate Change," Schlesinger said. "In fact, climate sensitivities as high as 9 degrees Celsius are not implausible. Paralysis in near-term action to significantly reduce emissions could make mitigation nearly impossible to attain."
Two other authors and one of the book's editors will also participate in the news conferences. The May 9 news conference will begin at noon EDT at JP Morgan-Chase corporate headquarters in Manhattan. The May 10 news conference will begin at 4 p.m. in Room 485 of the Russell Senate Office Building.
Editor's note: To reach Michael Schlesinger, call 217-778-9891; e-mail: firstname.lastname@example.org.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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