By Juliet Eilperin
Washington Post Staff Writer
Tuesday, October 6, 2009 12:33 AM
With enough technological advances, the world could get to a dramatically lower level of greenhouse gas emissions at a cost of between one and three percent of global GDP per year, according to a report issued Tuesday by a group of economists. That price tag is in line with previous economic estimates aimed at meeting more modest climate goals.
Frank Ackerman, an economist at the Stockholm Environment Institute and Tufts University and the report's lead author, said the study looked at what it would take to meet the recommendations of climate scientists who call for reducing carbon atmospheric concentrations from their current level to 350 parts per million.
The current level of carbon concentrations are 387 parts per million, compared to pre-industrial levels of 275. Most climate scientists have said the world must not allow these concentrations to grow beyond 450 parts per million to avoid dangerous climate impacts, but recently a group of researchers and environmental activists have suggested the world's nations must bring atmospheric concentrations down to 350 parts per million in order to curb serious sea level rise, drought and other major environmental problems.
"When we're looking at something that's of this magnitude, that affects our way of life . . . The question becomes, what is the least-cost way of achieving it?" Ackerman said.
The authors of the report assumed that a doubling of carbon concentrations in the atmosphere would translate into an average global temperature rise of 10.8 degrees Fahrenheit, twice as much as what some traditional climate models have suggested. According to their analysis, policymakers could reduce carbon concentrations in the atmosphere to 350 parts per million by either 2100 or 2200.
However Robert J. Shapiro, chairman of the U.S. Climate Task Force and Sonecon, an economic advisory group, said the goal of reducing carbon concentrations below their current levels is unrealistic.
"The only prospect of reaching 350 is if we came to develop a technology that would pull greenhouse gases out of the atmosphere -- that is, pull the concentrations out of the atmosphere," Shapiro said. "That is probably impossible without a technology that we can only conceive of today."
Kristen Sheeran, who directs a group called Economists for Equity and Environment, acknowledged the world would need radical technological innovations to achieve the group's ambitious targets. "It's hard to see how to do that without negative carbon technologies," said Sheeran, whose network is a project of Ecotrust, an environmental restoration group.