Nearly 200 nations are set to hold talks in Qatar to extend a U.N.-led plan for fighting climate change into 2013. The talks come amid pleas for tougher action to slow rising greenhouse gas emissions.

In this Wednesday, Nov. 20, 2012 file photo, a conference flags is displayed ahead of the Doha Climate Change Conference, in Doha, Qatar, Wednesday, Nov. 20, 2012.

The U.N. conference will try to prolong the U.N.'s Kyoto Protocol, the only legally binding U.N. plan for cutting emissions by developed nations. The meeting will also seek to lay foundations for a pact meant to start in 2020, which would bind all nations -- not just the rich -- to curb emissions.

A U.N. study last week showed that the world was on target for a rise in temperatures of 3 to 5 degrees Celsius, which would disrupt food and water supplies.

A U.N. conference two years ago agreed to limit any rise in temperatures to below 2 degrees Celsius. However, greenhouse gas levels hit a new record in 2011.