Action Needed To Manage Climate Change Risks New Report

Warning that the risk of dangerous climate change impacts is growing with every ton of greenhouse gases emitted into the atmosphere, a National Research Council committee today reiterated the pressing need for substantial action to limit the magnitude of climate change and to prepare to adapt to its impacts. The nation's options for responding to the risks posed by climate change are analyzed in a new report and the final volume in America's Climate Choices, a series of studies requested by Congress. The committee that authored the report included not only renowned scientists and engineers but also economists, business leaders, an ex-governor, a former congressman, and other policy experts. "The goal of the America's Climate Choices studies is to ensure that climate decisions are informed by the best possible scientific knowledge, analysis, and advice, both now and in the future," said committee chair Albert Carnesale, chancellor emeritus and professor, University of California, Los Angeles.

The new report reaffirms that the preponderance of scientific evidence points to human activities -- especially the release of carbon dioxide and other greenhouse gases into the atmosphere -- as the most likely cause for most of the global warming that has occurred over the last several decades. This trend cannot be explained by natural factors such as internal climate variability or changes in incoming energy from the sun. The report adds that the impacts of climate change on human and natural systems can generally be expected to intensify with warming.

While it recognized that climate change is inherently a global issue requiring an international response, the committee focused on the charge from Congress to identify steps and strategies that U.S. decision makers could adopt now. A coordinated national response to climate change, which the country currently lacks, is needed and should be guided by an iterative risk management framework in which actions taken can be revised as new knowledge is gained.

"America's response to climate change is ultimately about making choices in the face of risk," noted committee vice chair William L. Chameides, dean of the Nicholas School of the Environment, Duke University, Durham, N.C. "Risk management strategies must be durable enough to promote sustained progress yet sufficiently flexible to take advantage of new knowledge and technologies."

Substantial reductions of greenhouse gas emissions should be among the highest priorities in the national response, the committee said. Although the exact magnitude and speed of reductions will depend on how much risk society deems acceptable, it would be imprudent to delay taking action. The committee cited many reasons for not waiting, including that the faster emissions are reduced, the lower the risks. And because the effects of greenhouse gases can take decades to manifest and then persist for hundreds or even thousands of years, waiting for impacts to occur before taking action will likely be too late for meaningful mitigation. Beginning emissions reductions soon will also lower the pressure to make steeper and costlier cuts later. "It is our judgment that the most effective strategy is to begin ramping down emissions as soon as possible," Carnesale said.