Pressure on the U.N. secretary-general to call an emergency climate summit grew on Wednesday after some of the world's top polluters said they would be interested in attending.
Yvo de Boer, head of the U.N. Climate Change Secretariat, said support for a summit has been expressed by Japan, Germany, China, India and a number of developing countries.
Climate change talks in December will seek a successor to the Kyoto Protocol, which expires in 2012, and Secretary-General Ban Ki-moon is being lobbied to call a crisis summit of world leaders to set ground rules for that meeting.
A study last week by leading scientists blamed human activities such as burning fossil fuels for accelerated warming and U.N. officials and campaigners hope the findings will spur governments to curb greenhouse gas emissions.
While Ban assesses how much political support he has for calling a summit, de Boer said he had seen more encouraging signs -- including from the United States, the world's biggest emitter of carbon dioxide.
"The U.S. energy secretary, while rejecting the notion of mandatory emission caps, has said he feels there should be a global response to climate change," de Boer said.
"I interpret that to mean we need a global discussion on how we move forward."
In its starkest warning yet, the United Nations on Friday said warming may trigger more storms, floods, droughts, heatwaves and rising seas. It also said it was at least 90 percent certain humans were to blame for most warming over the last 50 years.
That was up from a 66 percent probability in the last report by the authoritative group of 2,500 scientists in 2001.
Kyoto obliged 35 developed nations to cut carbon dioxide emissions by at least 5 percent below 1990 levels, and the challenge for any successor treaty is to bring on board the United States and rapidly growing economies like China and India which were not bound by the original treaty.
Achim Steiner, executive director of the U.N. Environment Programme, said national politicians must take the lead.
"If there is no political impetus to these discussions this year, then I think we will have to face a situation where progress will be very slow, if not impossible."
