The US Environmental Protection Agency (EPA) today announced that greenhouse gases (GHGs) threaten the public health and welfare of the nation’s citizens.

The finding is significant, as it makes it possible for the Obama administration to begin regulating GHGs even if the Congress doesn’t approve a climate bill.

“Today’s finding is based on decades of research by hundreds of researchers,” said EPA Administrator Lisa P. Jackson at a briefing today. “The vast body of evidence not only remains unassailable, it’s grown stronger, and it points to one conclusion: greenhouse gases from human activity are increasing at unprecedented rates and are adversely affecting our environment and threatening our health.”

The EPA finding points to GHGs as the primary driver of climate change, which can lead to hotter, longer heat waves that threaten the health of the sick, poor or elderly; increases in ground-level ozone pollution linked to asthma and other respiratory illnesses; as well as other threats to the health and welfare of US citizens.

“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,” Jackson said. “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 GHGs and reduce the dependence on foreign oil that threatens our national security and our economy.”

The EPA’s final findings respond to the 2007 US Supreme Court decision that GHGs fit within the Clean Air Act definition of air pollutants. The findings do not in and of themselves impose any emission reduction requirements but rather allow EPA to finalize the GHG standards proposed earlier this year for new light-duty vehicles as part of the joint rulemaking with the Department of Transportation.

On-road vehicles contribute more than 23 per cent of total US GHG emissions. The EPA’s proposed GHG standards for light-duty vehicles, a subset of on-road vehicles, would reduce GHG emissions by nearly 950 million metric tonnes and conserve 1.8 billion barrels of oil over the lifetime of model year 2012-2016 vehicles.

The EPA’s endangerment finding covers emissions of six key greenhouse gases — carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride — that have been the subject of scrutiny and intense analysis for decades by scientists in the United States and around the world.

Scientific consensus shows that as a result of human activities, GHG concentrations in the atmosphere are at record high levels and data shows that the Earth has been warming over the past 100 years, with the steepest increase in warming in recent decades. The evidence of human-induced climate change goes beyond observed increases in average surface temperatures; it includes melting ice in the Arctic, melting glaciers around the world, increasing ocean temperatures, rising sea levels, acidification of the oceans due to excess carbon dioxide, changing precipitation patterns, and changing patterns of ecosystems and wildlife.

President Obama and Jackson have publicly stated that they support a legislative solution to the problem of climate change and Congress’ efforts to pass comprehensive climate legislation. However, the EPA states that climate change is threatening public health and welfare, and it is critical that the agency fulfill its obligation to respond to the 2007 US Supreme Court ruling that determined that greenhouse gases fit within the Clean Air Act definition of air pollutants.

The EPA issued its proposed findings in April 2009 and held a 60-day public comment period. The agency received more than 380,000 comments, which were carefully reviewed and considered during the development of the final findings.

• Where are we headed? A green future, or carbon doom?
• Science finds greenhouse gases even stronger than CO2, methane
• Official says UK’s CO2 reduction claims are ‘unsatisfactory’
• UK firms disclosing more on carbon emissions, could do better
• Businesses get new help to measure, reduce carbon emissions
• 3 Chinese power firms pollute more than all of UK
• Insulation, green energy could bring 70,000 jobs
• Better carbon management could mean £14 billion for N Ireland
• World’s first real-time global carbon counter makes debut
• Scotland sets out vision for low-carbon future