Ice sheets are melting more quickly and Arctic sea ice is disappearing much faster than previously projected, and significant sea level rise is more certain than ever, according to a new global scientific synthesis prepared by some of the world’s top climate scientists.
In a special report called “The Copenhagen Diagnosis” issued on Nov. 24, the 26 researchers, including Eric Steig from the UW, conclude that several important aspects of climate change are occurring as fast as or even faster than expected just a few years ago. The report comes in advance of the Copenhagen climate summit, scheduled for Dec. 7-18.
Steig, a UW professor of Earth and space sciences and a board member of the UW Program on Climate Change, said the report isn’t surprising for those who have been following the scientific literature. It provides a considerably more complete picture on several key issues, particularly near-term sea level rise, than the 2007 report from the Intergovernmental Panel on Climate Change, he said.
“It also articulates a much clearer picture of what has to happen if the world wants to keep future warming within the reasonable threshold of 2 degrees Celsius that most scientists believe is prudent,” Steig said.
That threshold was agreed upon by leaders of the Group of Eight nations during a summit in July, though the agreement currently is non-binding.
The “Copenhagen Diagnosis,” which took a year to complete, is a synthesis of hundreds of research papers about human-induced climate change that have been published since the most recent assessment by the Intergovernmental Panel on Climate Change in 2007. The new report says that satellite and direct measurements show:
- Greenland and Antarctic ice sheets are losing mass and contributing to sea level rise at an increasing rate.
- Arctic sea ice has melted far beyond the expectations of climate models.
- Sea level has risen more than 2 inches in the last 15 years, about 80 percent more than expected, and could rise 3 to 6.5 feet by the end of the century.
- Carbon dioxide emissions from fossil fuels in 2008 were about 40 percent higher than in 1990.
“This report shows that, contrary to the claims of `skeptics,’ the scientific community actually underestimated both the magnitude and the rate of global climate change,” said Edward Miles, a UW professor of marine affairs and director of the Pacific Northwest Climate Impacts Group at the UW.
“In addition, since 2005 the growth in fossil fuel emissions exceeds the worst-case scenarios of the Intergovernmental Panel on Climate Change, demonstrating clearly that world population growth and increasing demands for fossil fuels from the developing world are now a major driver of climate change,” said Miles, who was not involved in preparing “The Copenhagen Diagnosis.”
“These trends raise serious questions about our ability to manage changing rates and magnitudes of change in the future and increasingly severe questions about environmental security.”
The “Copenhagen Diagnosis” noted that even if emissions do not increase beyond today’s levels, in 20 years there still would be a one-in-four chance that the world cannot limit warming to less than 2 degrees Celsius, or 3.6 degrees Fahrenheit.
Of the 26 authors of the report, six are from the United States. Most of the collaborating scientists are authors of previous reports for the Intergovernmental Panel on Climate Change, which was established in 1988 by the United Nations and the World Meteorological Organization and which shared the 2007 Nobel Peace Prize.