By Juliet Eilperin
Washington Post Staff Writer
Friday, October 19, 2007
The president's top science adviser said yesterday there is no solid scientific evidence that the widely cited goal of limiting future global temperature rises to two degrees Celsius above pre-industrial levels is necessary to avert dangerous climate change, an assertion that runs counter to that of many scientists as well as the Nobel Prize-winning Intergovernmental Panel on Climate Change.
John H. Marburger III, director of the White House Office of Science and Technology Policy, said at a news conference that the target of preventing Earth from warming more than two degrees Celsius, or 3.6 degrees Fahrenheit, "is going to be a very difficult one to achieve and is not actually linked to regional events that affect people's lives."
A wide number of scientists, as well as European leaders and many U.S. lawmakers, have endorsed the goal of limiting global temperature rise to that level. That roughly translates to holding the buildup of greenhouse gases in the atmosphere to 450 parts per million of carbon dioxide or equivalents, compared with the current level of roughly 385 parts per million.
The atmosphere has already warmed by 1.4 degrees Fahrenheit compared with pre-industrial levels. In its April report, the IPCC outlined a range of environmental impacts that could transpire if temperatures rise 1.8 to 3.6 degrees Fahrenheit above 1980 levels. These include placing between 20 and 30 percent of all species "at increasing risk of extinction" damaging most coral reefs; and "increased morbidity and mortality from heat waves, floods and droughts."
Marburger said that while there is general agreement that human activity is producing too much carbon dioxide and "you could have emerging disasters long before you get to two degrees. . . . There is no scientific criterion for establishing numbers like that."
President Bush convened a meeting of delegates from the world's major economies last month in an effort to begin discussing what to adopt at as the long-term goal for reducing greenhouse gas emissions. But he and his advisers have yet to say what that goal will be.
Alden Meyer, director of strategy and policy for the Union of Concerned Scientists, backs the goal of limiting future temperature rise to two degrees Celsius and said the administration needs to define its own goal if it rejects those of other world leaders.
"The question for [Marburger] is, if not two degrees, what?" Meyer asked.