Representatives from nearly 200 nations have begun two weeks of talks aimed at agreements on how to limit greenhouse gas emissions.

Delegates at the U.N. climate change conference in Doha, Qatar will chiefly tackle extending the Kyoto Protocol. The pact, which expires this year, binds developed countries to cut emissions by 5 percent below 1990 levels.

Major greenhouse gas emitters like the United States and China are not part of the deal, while Russia, Japan and Canada say they do not want to be part of an extension to the Kyoto agreement. That would leave only about 15 percent of the world's greenhouse gas emissions covered under a continuation of the pact.

The conference will also include talks on crafting a new global climate deal that would be finalized by 2015 and go into effect in 2020.

The talks come after a U.N. report, released last week, warned of the need for accelerated action in order to keep worldwide temperatures from rising up to 2 degrees Celsius above pre-industrial levels.

It said greenhouse gas emissions have risen 20 percent since 2000, and that without any further pledges of action, global temperature rise is likely to reach between 3 and 5 degrees Celsius by the end of the century.

Scientists worldwide overwhelmingly agree that billions of tons of man-made carbon dioxide emissions pumped into the Earth's atmosphere over the last 100 years are largely to blame for global warming.