In a signal the Obama administration is prepared to act without congressional action, the US 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 US 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. ``The question is will they use it that way, or are they using it as a bargaining chip to threaten action, and get Congress to act instead,' said Damon Moglen, of Greenpeace USA.
Conference president Connie Hedegaard said the key to an agreement is finding a way to raise and channel public and private financing to poor countries for years to come to help them fight the effects of climate change. Hedegaard Denmark's former climate minister said if governments miss their chance at the Copenhagen summit, a better opportunity may never come.
``This is our chance. If we miss it, it could take years before we got a new and better one. If we ever do,' she said. The conference opened with video clips of children from around the globe urging delegates to help them grow up without facing catastrophic warming. On the sidelines, climate activists competed for attention to their campaigns on deforestation, clean energy and low-carbon growth.
Mohamad Shinaz, an activist from the Maldives, plunged feet-first into a tank with nearly 200 gallons (750 liters) of frigid water to illustrate what rising sea levels were doing to his island nation. ``I want people to know that this is happening,' Shinaz said as the water reached up to his chest. ``We have to stop global warming.'
Leah Wickham, a 24-year-old from Fiji, broke down in tears as she handed a petition from 10 million people asking the negotiators at Copenhagen to come up with a deal to save islands like hers. ``I'm on the front lines of climate change,' she said. ``The evidence is now overwhelming' that the world needs early action to combat global warming, said Rajendra Pachauri, the head of the Intergovernmental Panel on Climate Change, an UN expert panel.
He defended climate research in the face of a controversy over e-mails pilfered from a British university, which global warming sceptics say show scientists have been conspiring to hide evidence that doesn't fit their theories. ``The recent incident of stealing the e-mails of scientists at the University of East Anglia shows that some would go to the extent of carrying out illegal acts perhaps in an attempt to discredit the IPCC,' he told the conference.