Working sessions have begun and that means negotiators are faced with tackling the issues on the table. The goal is to come up with substantive, but workable solutions to cut greenhouse gas emissions, promote new, eco-friendly technologies, but also promote economic growth and investment and help the less developed nations to adapt to these new conditions.
The U.N. top climate official, Yvo de Boer reminded delegates they have their work cut out.
"Negotiators need to come up with, during the next week, with solid proposals that can constitute the foundation stones an agreed outcome," de Boer said.
There are reminders of what is at stake, with the U.N. weather agency reporting that this decade is likely to be the warmest on record and 2009 the fifth warmest year since record keeping began in 1850.
The head of the World Meteorological Organization, Michel Jarraud, said most areas of the world had above normal temperatures in 2009.
"In large parts of southern Asia, central Africa, these regions are likely to have the warmest year on record," Jarraud said.
Most scientists believe the warming trend is mainly caused by human activity, especially the use of fossil fuels and the cutting down of forests. Skeptics say global warming is part of a natural cycle of climate change.
In Copenhagen, experts and officials alike are putting the emphasis on what people and governments can do to cut the emission of greenhouse gasses.
Scientists say a 25 to 40 percent cut in carbon-dioxide emissions is needed to control global warming. The European Union, China, and India have already pledged reductions. The United States is waiting for Congressional approval for a proposal put forward by the Obama administration.
The U.N.'s de Boer says there is still much discussion about the pledges.
"What I have heard representatives of both Europe and the United States say is that the target that China has tabled can be improved upon," de Boer said. "What I have heard representatives of Europe and China say is that the target the United States has tabled can be improved upon.
De Boer added that African countries and other less developed nations say nobody's targets are good enough at the moment.
In Washington Monday, the U.S. Environmental Protection Agency declared greenhouse gasses a "threat to public health and the welfare of the American people." That opens the way for the agency to potentially regulate emissions, if Congress does not.
In Copenhagen the EPA finding has been welcomed as a positive step. Damon Moglen is global warming campaign director for the environmental group, Greenpeace. He tells VOA tougher action must follow.
"This is am important first step, but it is only a first step,"Moglen said. "We need to see EPA regulation of greenhouse gases immediately and we need to see aggressive regulation of greenhouse gases."
Moglen says the EPA announcement risks being seen as a political gesture unless the U.S. puts, higher emissions cut proposals on the table here. And, he says President Obama needs to take a clear lead on climate change when he attends the summit next week.