NAIROBI, Kenya (AP) - The top U.N. official for the environment asked Secretary-General Ban Ki-moon on Tuesday to convene an international summit to combat climate change, an official said, joining a chorus of world leaders and scientists calling for urgent action to cut greenhouse gases.

Ban met with the executive director of the U.N. Environment Program, Achim Steiner, who recommended the summit take place later this year, an official close to the talks said.

Ban was sympathetic to the idea, the official said on condition of anonymity because the talks were not public.

"Climate change is one of the most important and urgent agendas that the international community has to address before 2012," the U.N. chief said.

Yvo de Boer, executive secretary of the U.N. Framework Convention on Climate Change, had said earlier this month that he would ask Ban to organize a conference of world leaders.

Discussions about the summit come as an authoritative report, compiled by 2,000 climate experts and other scientists, is expected to be released Friday in Paris, warning that human-caused global warming is destined to get much worse. The report is by the Intergovernmental Panel on Climate Change, which was created by the United Nations in 1988 and releases its assessments every five to six years.

Kenya has agreed to host a possible summit, Ban said. He is scheduled to meet Kenyan president Mwai Kibaki on Wednesday to discuss such a meeting.

Nick Nuttall, spokesman for the U.N.'s Environment Program, said the summit could be held between July and December.

Nuttall said the impetus for such a summit is the acknowledgment by President Bush in his State of the Union speech last week that climate change needs to be addressed, as well as the Jan. 10 proposals by the European Union for a new European energy policy that stresses the need to slash carbon emissions blamed.

"There's a lot of momentum that has been building," for such a summit, Nuttall said. "We have a window of opportunity."

World temperatures have risen to levels not seen in thousands of years, propelled by rapid warming the past 30 years, scientists say. They attribute at least some of the past century's 1-degree rise in global temperatures to the atmospheric accumulation of carbon dioxide and other heat-trapping gases, byproducts of power plants, automobiles and other fossil fuel-burning sources.

Climate change "is a priority of the secretary-general" and a problem he has repeatedly raised in diplomatic talks, including his recent meetings with Bush and French President Jacques Chirac, said Ban's spokeswoman, Michele Montas, in New York.

"Is he going to support a summit? We don't know yet," she said.

The two warmest years on record for the world were 2005 and 1998. Last year was the hottest year on record for the United States.

Scientists have said that continued temperature increases could seriously disrupt the climate.

The 1997 Kyoto Protocol requires 35 industrialized nations to reduce their greenhouse emissions by 5 percent below 1990 levels by 2012.

The U.S. and Australia are the only major industrial nations to reject Kyoto.

Kyoto parties are discussing what kind of timetables and quotas should follow that pact's expiration in 2012.

They also are weighing ways to draw the United States, the world's biggest carbon dioxide emitter, into a mandatory system of emissions caps. Many look toward the scientists' upcoming assessment for support.

Although Bush has acknowledged climate change needs to be addressed, he opposes mandatory emission caps, arguing that industry through development of new technologies can deal with the problem at less cost.

In Washington, meanwhile, two private advocacy groups told a congressional hearing that climate scientists at seven government agencies say they have been subjected to political pressure aimed at playing down the threat of global warming.

The groups presented a survey that shows two in five of the 279 climate scientists who responded to a questionnaire complained that some of their scientific papers had been edited in a way that changed their meaning. Nearly half of the 279 said in response to another question that at some point they had been told to delete reference to "global warming" or "climate change" from a report.

The questionnaire was sent by the Union of Concerned Scientists, a private advocacy group. The report also was based on "firsthand experiences" described in interviews with the Government Accountability Project, which helps government whistleblowers, lawmakers were told.

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