World should halve greenhouse gases by 2050: U.N.

By Alister Doyle, Environment Correspondent

OSLO (Reuters) - A new U.N. treaty to fight climate change should aim to halve greenhouse gas emissions by 2050, the U.N.'s top climate change official said on Friday.

Senior officials from up to 190 nations will meet from March 31-April 4 in Bangkok for the opening session of two years of meetings to work out a new global warming pact to widen and succeed the United Nations' Kyoto Protocol.

Yvo de Boer, head of the U.N. Climate Change Secretariat in Bonn, said that studies by the U.N. Climate Panel indicated that emissions of greenhouse gases had to peak within 10 to 15 years and halve by mid-century to avert the worst effects of warming.

"That for me personally is the measure of success," he told Reuters, saying the goals should be cornerstones of a broad treaty due to be agreed in Copenhagen in December 2009. "It's not going to be easy."

World emissions of heat-trapping gases, mainly from burning fossil fuels, are rising sharply despite efforts to avert a warming that could bring ever more droughts, disease, mudslides, heatwaves and rising ocean levels.

De Boer added that mid-term targets, such as 2020 for developed countries, may be harder to agree than a long-term 2050 goal that will be achieved by future generations. "It's the bit in between that's difficult," he said.

China, drawing level with the United States as the top emitter of greenhouse gases, urged rich nations in a statement to the Bangkok meeting to live up to a guideline they agreed last year of 2020 cuts of 25 to 40 percent below 1990 levels.

The Bangkok talks are the first of a series meant to end in December 2009 with agreement on a pact that will include actions by all nations.