FACTBOX: What are the U.N. Bangkok climate talks?

(Reuters) - Delegates from up to 190 nations will meet in Bangkok from March 31-April 4 for the first round of U.N. talks on a sweeping new pact to fight climate change.

The Bangkok meeting, totalling about 1,000 delegates led by senior government officials, will be the first formal U.N. negotiations on a U.N. climate treaty since the Kyoto Protocol was negotiated from 1995-97.

* WHY IS A NEW TREATY NEEDED?

-- The U.N. Climate Panel last year blamed human activities, led by burning fossil fuels, for a warming that it said would bring ever more droughts, heatwaves, floods and rising seas.

The panel said that world emissions of greenhouse gases -- now rising fast -- would have to peak by about 2015 and then fall sharply to limit a rise in global temperatures to no more than 2 Celsius (3.6 Fahrenheit) above pre-industrial times.

Spurred by the panel's findings, governments agreed in Bali, Indonesia, in December 2007 to work out a new climate treaty by the end of 2009 to succeed Kyoto. Bangkok will be the first stop on the "Bali roadmap".

* SO WHAT'S WRONG WITH THE KYOTO PROTOCOL?

-- Kyoto obliges 37 developed nations to cut greenhouse gas emissions by an average of at least 5 percent below 1990 levels by 2012. The Bangkok talks will be about widening action to all nations.

Every rich country except the United States has ratified Kyoto. President George W. Bush rejected the pact in 2001, saying it would cost U.S. jobs and unfairly omitted 2012 emissions targets for developing nations such as China and India.

The Bush administration has agreed to take part in talks on a long-term treaty even though many details will be agreed after Bush steps down in January 2009. The main U.S. presidential candidates say they are committed to stepping up U.S. action.

Developing nations say they are willing to do more to curb the growth of their emissions -- but reject Kyoto-style caps because they need to use more energy to reduce poverty.

* WHAT WILL BE ACHIEVED IN BANGKOK?

-- Bangkok's main task is to agree a work programme for the next two years -- the details may show how urgently governments want to tackle climate change. After Bangkok, negotiators will meet in Bonn in June, again in August in a city yet to be decided and environment ministers will meet in Poznan, Poland, in December. Bangkok is symbolically important as the first step on the road to a deal to be agreed in Copenhagen in late 2009.

* BUT KYOTO RUNS TO 2012: WHAT'S THE HURRY?

-- The United Nations says that a new treaty needs to be in place by the end of 2009 to give national parliaments time to ratify before Kyoto runs out. A big worry is that it took two years to negotiate Kyoto and then eight to get it ratified.

And investors need time -- a power company trying to decide whether to build a coal-fired plant or a wind farm wants to know the rules on greenhouse gas emissions as soon as possible.