by Juliet Eilperin

WASHINGTON -- Negotiators from the United States are trying to weaken the language of a climate change declaration set to be unveiled at next month's G-8 summit of the world's leading industrial powers, according to documents.

A draft proposal dated April 2007 that is being debated in Bonn by senior officials of the Group of Eight includes a pledge to limit the global temperature rise this century to 3.6 degrees Fahrenheit, as well as an agreement to reduce worldwide greenhouse gas emissions to 50 percent below 1990 levels by 2050.

The United States is seeking to strike that section, according to documents obtained by The Washington Post.

Many scientists have warned that an increase of more than 3.6 degrees this century could trigger disastrous consequences such as mass extinction of species and accelerated melting of polar ice sheets, which would raise sea levels.

The documents indicate that American officials are also trying to eliminate draft language that says, "We acknowledge that the UN climate process is the appropriate forum for negotiating future global action on climate change." Industrial and developing countries have used the United Nations as the forum for crafting climate agreements for years.

Neither the White House Council on Environmental Quality nor the State Department could immediately be reached for comment. Since taking office in 2001, President Bush has consistently advocated more climate research and voluntary energy-efficiency measures as the way to address global warming.

The G-8 leaders are scheduled to sign off on the global warming declaration during their June 6-8 summit in Heligendamm, Germany.

Chancellor Angela Merkel of Germany, along with outgoing Prime Minister Tony Blair of Britain, have been pushing for a strong statement on climate change as part of the June meeting, and newly elected President Nicolas Sarkozy of France said in his acceptance speech last week that global warming is his top priority.

The US representatives in Bonn, however, are trying to soften the message of the statement by deleting sections that would call on the industrialized world to modify activities linked to warming.

They also proposed striking one of the document's opening phrases, which says, "We firmly agree that resolute and concerted international action is urgently needed in order to reduce global greenhouse gas emissions and sustain our common basis of living."

Philip Clapp, who heads the advocacy group National Environmental Trust and has read the document, said US opposition to the draft declaration could strain the country's relationship with its allies and jeopardize the world's ability to cut greenhouse gas emissions in the coming decade.

"The administration is proposing to eliminate any statement that acting on global warming is urgent and all measures that will begin to reduce global warming pollution, including any proposal to improve the energy efficiency of our economy," Clapp said. "A continued US refusal to take a lead in combating global warming will set back progress for years."

In New York today, former president Bill Clinton and New York Mayor Michael Bloomberg will convene an international meeting of government officials and business leaders to trade ideas on ways to curb global warming.

Mayors and governors of more than 30 localities from Colombia to South Korea, along with chief executives from international companies, will join Clinton and Bloomberg for the conference that ends Thursday.

Although cities cover less than 1 percent of the earth's surface, they are disproportionately responsible for polluting it, contributing 80 percent of greenhouse gas emissions.

"Cities must take responsibility for our contribution to global climate change," said Mayor Antonio Villaraigosa of Los Angeles, one of the participants. He will announce his own city's carbon-reduction plan tomorrow in California before traveling to New York.

The New York conference will include discussions on building greener cities, using renewable energy sources, transforming waste into energy, and finding ways to engage the private sector in the effort.

Bloomberg recently unveiled a 23-year plan to make New York sustainable over the long term. The city now has 8.2 million people and by 2030, there will be an additional million people living there. Conference participants are expected to discuss Bloomberg's most controversial program, which proposes charging motorists extra money for driving into the most congested parts of Manhattan as a way to reduce traffic and pollution.

The state Legislature must approve the congestion-pricing scheme, and many say it is a near-impossible hurdle because a great number of lawmakers from the city's outer neighborhoods of commuters will not support it.

The Bloomberg administration wants to reduce New York's emissions by 30 percent by 2030.

Greenhouse gases, including carbon dioxide, methane, and other gases, essentially trap energy from the sun. City buildings, which consume electricity, natural gas, fuel oil, and steam, contribute heavily to emissions.

Material from the Associated Press was included in this report.

© Copyright 2007 The Boston Globe