For the next two weeks, more than 100 heads of state will debate how to reduce emissions at the United Nations Framework Convention on Climate Change.
The Copenhagen, Denmark, meeting is the largest climate change conference ever assembled. Environmentalists from 192 nations are meeting to figure out how to cut greenhouse gases and try to impose collective deadlines on doing so.
"We want a fair, ambitious and binding treaty for the Copenhagen summit," said Abigail Jabines of Greenpace.
As the conference kicked off Monday, the Obama administration signaled the U.S. is ready to act.
Meanwhile, the Environmental Protection Agency announced that greenhouse gases are a health hazard and must be regulated.
The U.N. is looking to cut greenhouse gases by between 25 and 40 percent in the next 10 years.
"The science has never been stronger," claimed Connie Hedegaard, Denmark's climate minister. "The solutions have never been more abundant."
Americans, however, are growing more skeptical of dire claims that man-caused global warning will destroy the planet.
Opponents say the solutions discussed in Copenhagen could carry a price tag of untold billions for the world's wealthier nations, including the United States. They add that there is a clear political agenda at work in Copenhagen.
"You know the problem with this United Nations governmental panel on climate change is that the senior authors are all appointed by their government," explained Pat Michaels, senior fellow at the Cato Institute. "So by definition, it's politicized unfortunately and there have been a lot of flaws found in the most recent report."
The summit is being held in the wake of an email scandal that shows leading global warming scientists tried to suppress and discredit their opponents.
"I actually think it's very good that what has happened is being critically addressed in the media because this process has to be based on solid science," Yvo De Boer, executive secretary of the climate change conference, said.
President Obama will head to Copenhagen next week for the conference.
Monday he met with former Vice President Al Gore, the nation's global warming guru.
The EPA's ruling that greenhouse gases are dangerous is another signal that the White House plans to take the country to a new level of environmental regulation.