U.N. climate conference opens with pressure on U.S.

COPENHAGEN — The largest and most important U.N. climate change conference in history opened Monday, with organizers warning diplomats from 192 nations that this could be the last, best chance for a deal to protect the world from calamitous global warming.

Negotiations have dragged on for two years and only recently have shown signs of breakthroughs with new commitments from major emitters such as the United States, China and India to control greenhouse gas emissions.

In a signal the Obama administration is prepared to act without congressional action, the U.S. Environmental Protection Agency said it has concluded that greenhouse gases are endangering Americans' health and must be regulated.

The two-week conference convened in an upbeat mood after a series of promises by rich and emerging economies to curb their greenhouse gases. Still, major issues have yet to be resolved.

At stake is a deal that aims to wean the world away from fossil fuels and other pollutants to greener sources of energy, and to transfer hundreds of billions of dollars from rich to poor countries every year over decades to help them adapt to climate change.

Scientists say without such an agreement, the Earth will face the consequences of ever-rising temperatures, leading to the extinction of plant and animal species, the flooding of coastal cities, more extreme weather events, drought and the spread of diseases.

With the commitments remaining short of scientists' demands, the pressure was on those major emitters for bigger cuts. Swedish Environment Minister Anders Carlgren, speaking for the European Union, said it would be "astonishing" if President Barack Obama came for the final negotiation session "to deliver just what was announced in last week's press release."

The U.S. EPA said the scientific evidence surrounding climate change clearly shows that greenhouse gases "threaten the public health and welfare of the American people" and that the pollutants — mainly carbon dioxide from burning fossil fuels — should be regulated under the Clean Air Act.

American business groups have strongly argued against tackling global warming through the Clean Air Act, saying it is less flexible and more costly than the bill being considered before Congress. On Monday, some of those groups questioned the timing of the EPA announcement, calling it political.

Climate activists in Copenhagen said the decision could help the Obama administration move ahead on climate policy without waiting for action from Congress.