Nearly two years after the U.S. Supreme Court directed the Environmental Protection Agency to determine whether carbon dioxide is a pollutant that endangers public health and welfare, the EPA has prepared and forwarded a so-called "endangerment finding" that could result in the regulation of carbon dioxide and other greenhouse gases under the federal Clean Air Act. At this point the EPA has only prepared a finding, and is not proposing how greenhouse gases should be regulated, but approval of the finding would be expected to initiate that discussion.
EPA's finding is expected to be published in the Federal Register in April, followed by a 60-day public comment period and public hearings, prior to finalization. The finding follows comments from EPA Administrator, Lisa Jackson, suggesting that she would declare global warming a public health threat. While MSNBC has reported that environmental groups are pleased with the proposed finding, critics of the finding, including the United States Chamber of Commerce, worry about the increased volume of clean air permits that my be required if federal regulation of greenhouse gasses is implemented.
More information on EPA's proposed finding can be found here and here.