Global warming report released in Paris
February 2, 2007
The scientists said global warming was "very likely" -- with a greater than 90 percent level of confidence -- caused by human activity, specifically man's burning of fossil fuels. The report makes it clear that most of the currently observed global warming is not natural.
"Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level," the scientists said.
"The scientific debate is over," said Spencer Weart, director of American Institute of Physics's Center for History of Physics in College Park Maryland. "It now becomes an economic and political debate" over how to deal with the problem of global warming, he said.
This color-coded map shows a progression of changing global surface temperatures from 1893 to 2003. Dark red indicates the greatest warming and dark blue indicates the greatest cooling. Modified from a NASA animation.
The panel predicted temperature rises of 1.8-4.0 degrees C (3.2-7.2 degrees Fahrenheit) by the year 2100 and sea level rise of 18-58 cm (7-23 inches) by the end of the century. Should polar ice sheets continue to melt, oceans could rise by a further 8-20 cm (3.9-7.8 inches), said the report. Some scientists have expressed concern that IPCC projections on sea level change are too moderate.
"The data now available raise concerns that the climate system, in particular sea level, may be responding more quickly than climate models indicate," wrote a group of prominent scientists in today's issue of the journal Science. "Previous projections, as summarized by IPCC, have not exaggerated but may in some respects even have underestimated the change, in particular for sea level."
The report did not make recommendations on how governments should proceed to address global warming.
Policy experts at the University of New Hampshire and Boston University made their own forecasts on how the United States would eventually respond to climate change, including a national cap on carbon dioxide emissions; a national carbon dioxide cap-and-trade scheme partially modeled on existing regional and federal trading schemes for sulfur dioxide and nitrogen oxide; national, mandatory renewable energy portfolio standards; mandatory national product standards for increased energy efficiency; increased vehicle fleet gasoline efficiency standards (CAFE standards); and increased use of federal monetary incentives such as corporate tax credits for research and development and additional subsidies to consumers for the purchase of more energy efficient products including vehicles.
"Because the United States has often been reluctant to engage in international environmental policy-making and accept international environmental regulations before corresponding domestic action has been taken (particularly in the context of a highly contentious domestic issue such as climate change), developments in federal climate policy can be expected to induce changes in U.S. foreign policy," said Stacy VanDeveer, associate professor of political science at the University of New Hampshire, and Henrik Selin of Boston University in an article published today in the journal Review of Policy Research. "This means that significant changes in U.S. foreign policies related climate change are likely only after the enactment of more expansive federal climate change policy."
This article uses quotes from SciencExpress, the online version of Science, and a news release from University of New Hampshire.