The proposed finding, which now moves to a public comment period, identified six greenhouse gases that pose a potential threat -- gases that are emitted into the atmosphere by vehicles and many industrial plants.
"This finding confirms that greenhouse gas pollution is a serious problem now and for future generations," said EPA Administrator Lisa P. Jackson. She said the agency could develop regulations under the Clean Air Act to combat greenhouse gases, but the Obama administration would prefer that Congress addressed the issue through "cap-and-trade" legislation.
Medium and heavy-duty trucks contribute around 5 percent of the nation's greenhouse gases, and the predominant greenhouse gas emitted from the trucking industry is carbon dioxide. Exactly how greenhouse gas regulation might affect the trucking industry is at this point unclear. The American Trucking Associations earlier this year asked Congress to address the issue through actions such as enacting a national 65-mph speed limit and governing truck speeds; increasing funding for the EPA's SmartWay voluntary greenhouse gas reduction program; national fuel economy standards for medium- and heavy-duty trucks; financial incentives to increase the adoption of idling reduction technologies; and promoting the use of "more productive truck combinations" to result in fewer truck miles traveled.
EPA's proposed endangerment finding is based on rigorous, peer-reviewed scientific analysis of six gases - carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride - that have been the subject of intensive analysis by scientists around the world. The science clearly shows that concentrations of these gases are at unprecedented levels as a result of human emissions, and these high levels are very likely the cause of the increase in average temperatures and other changes in our climate.
The scientific analysis also confirms that climate change impacts human health in several ways. Findings from a recent EPA study titled "Assessment of the Impacts of Global Change on Regional U.S. Air Quality: A Synthesis of Climate Change Impacts on Ground-Level Ozone," for example, suggest that climate change may lead to higher concentrations of ground-level ozone, a harmful pollutant. Additional impacts of climate change include increased drought; more heavy downpours and flooding, more frequent and intense heat waves and wildfires, greater sea level rise, more intense storms, and harm to water resources, agriculture, wildlife and ecosystems.
More information: http://epa.gov/climatechange/endangerment.html