What to expect at the climate summit

Some 15,000 delegates, environmentalists, scientists, journalists and others gather in Copenhagen, Denmark, today to begin two weeks of negotiations on what to do about climate change. A look at what's happening there:

Q: Why is this meeting happening?

A: It's called "COP-15" for the 15th Conference of Parties to the 1992 U.N. Framework Convention on Climate Change. The 1992 deal is better known as the Rio treaty. That agreement was ratified by 192 nations, including the U.S. Since then, delegations have met each year to discuss how the world can combat global warming.

The most important previous meeting occurred in Kyoto, Japan, in 1997, when a treaty protocol ordered cuts in carbon dioxide and other global-warming gases from 37 industrialized nations. The U.S. rejected that pact.

Q: What is expected to be accomplished at Copenhagen?

A: Copenhagen is expected, at best, to reach political agreements on key elements, advancing talks into next year. The hope is a binding treaty could be signed then. Industrialized nations, including the U.S., are expected to cut emissions between 2012 and 2020. Developing nations also are expected to rein in fossil-fuel use and slow the growth in their emissions.

Another important element involves rich nations paying poor ones to help them deal with droughts, floods and other effects of climate change, and to install clean-energy technology to curb their own emissions.

Q: What would such a new international agreement do to stop global warming?

A: Experts say the emissions reductions pledged in recent days would fall far short of what's needed to keep temperatures from rising to dangerous levels. That benchmark is anything more than 2 degrees Celsius (3.6 degrees Fahrenheit) above temperatures before the Industrial Revolution, when man started widespread use of coal and other fossil fuels.