New gas mileage standards are one consequence of the EPA's ruling.

RODALE NEWS, EMMAUS, PA—Pointing to hundreds of scientific, peer-reviewed studies that have been conducted by climate experts all over the world over the course of decades, the U.S. Environmental Protection Agency (EPA) announced its final finding Monday that greenhouse-gas emissions have been found to threaten human health and welfare. The announcement came the same day that climate talks kicked off at the United Nations Climate Change Conference in Copenhagen, Denmark. "These long-overdue findings cement 2009's place in history as the year when the United States Government began addressing the challenge of greenhouse-gas pollution and seizing the opportunity of clean-energy reform," said EPA Administrator Lisa P. Jackson. "Business leaders, security experts, government officials, concerned citizens, and the United States Supreme Court have called for enduring, pragmatic solutions to reduce the greenhouse-gas pollution that is causing climate change. This continues our work towards clean-energy reform that will cut greenhouse gases and reduce the dependence on foreign oil that threatens our national security and our economy."

THE DETAILS: This announcement was a long time coming. Monday's final endangerment finding stems from a 2007 U.S. Supreme Court decision that found greenhouse gas fell within the Clean Air Act's definition of air pollutants. Ignored under the Bush Administration, the data was investigated by the Obama-era EPA; the draft endangerment finding was opened up to public comment and the final finding announced Monday. While it does not immediately impose emission-lowering requirements, the finding does allow the EPA to finalize greenhouse-gas standards proposed in April that would require that light-duty vehicles get improved gas mileage.

The EPA estimates that vehicles contribute nearly 25 percent of all U.S. greenhouse-gas emissions. The improved gas-mileage standards could cut these emissions by 950 million metric tons, conserving 1.8 billion barrels of oil over the lifetime of vehicles produced between 2012 and 2016. When regulations are in place in 2011, the largest emitters, such as coal-fired power plants, will be required to submit emission information and work with the EPA to use the best technology available to lower emissions in new plants or plant expansions. "In less than 11 months, we have done more to prevent climate change than in last eight years," Jackson said. Small- and mid-size businesses will not have to do this.

The endangerment finding isn't limited to the common greenhouse gas carbon dioxide, which comes mainly from vehicle tailpipes and coal-fired power plants that generate about half of the country's electricity. It also covers methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride.