The U.S. Environmental Protection Agency issued a tentative finding Friday declaring that high concentrations of greenhouse gases are bad for human health and the environment.

Issuing the proposed finding moves the government closer to regulating greenhouse gas emissions created by human activities, such as operating power plants and driving vehicles. The action also reflects the administration's intent to reverse some of the environmental policies championed by the Bush administration.

In a 2007 ruling, the U.S. Supreme Court said the federal government needed to decide whether to regulate emissions under the Clean Air Act. The EPA had argued that it didn't have the authority to do so. The agency didn't move quickly to follow the court's direction until the new administration took over.

Obama's administration is keen on developing comprehensive climate change legislation that would both boost job growth and battle global warming. One of the key components of that legislation would be a program to require polluters to cap emissions and pay for emitting more than permitted. Revenues from the program would then fund greentech developments and other initiatives, Obama has said.

In the proposed finding, the EPA identified six greenhouse gases it says are posing threats to human health and even national security. Scientific analysis shows that the amounts of carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride have reached dangerous levels as a result of human activities, the EPA said. The accumulation has likely caused the warming of the world's climate, which in turn could give rise to conflicts over water and other resources, the agency added.

Vehicle emissions are chief culprits for the increase in carbon dioxide, methane, nitrous oxide and hydrofluorocarbons, the EPA said.

"The effects of climate change observed to date and projected to occur in the future –including but not limited to the increased likelihood of more frequent and intense heat waves, more wildfires, degraded air quality, more heavy downpours and flooding, increased drought, greater sea level rise, more intense storms, harm to water resources, harm to agriculture, and harm to wildlife and ecosystems – are effects on public health and welfare within the meaning of the Clean Air Act," according to the proposed finding.

Already, rising sea levels and other environmental changes have created "climate change refugees." A recent documentary on PBS highlighted the plight of a tiny South Pacific island nation of Kiribati as a result of global warming. Kiribati has asked neighboring Australia and New Zealand to accept immigrants from the country because rising sea levels are taking over land where people used to live. Growing taro, the main food source for the island folks, has become more difficult. Coconut trees, another important source of food and materials, are dying because of the invading seawater.

Earlier this week, the EPA said emissions from the United States grew 1.4 percent in 2007 from the year before. An increase in fuel and electricity use contributed to the higher emissions number, the EPA said. There was a greater demand for heating fuel during the cold winter and electricity to power air conditioning during the summer. A drop in hydropower generation (14.2 percent) also made a difference.

The public will have 60 days to comment on the proposed finding. The EPA will then issue a final finding, which will allow the agency to eventually draft regulations. One public hearing is scheduled for May 18 at the Potomac Yard Conference Center in Arlington, Va., and another one for May 21 at the Bell Harbor International Conference Center in Seattle. 

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