July 9 (Bloomberg) -- The biggest polluting countries agreed to limit world temperatures and set a global emissions goal for 2050 by December, the first time developing nations such as China accepted the targets to fight climate change.

U.S. President Barack Obama, who led a meeting of the world’s largest carbon emitters today in L’Aquila Italy, said “important strides” were achieved and that all countries must work collectively to battle rising temperatures and sea levels.

“Every nation on this planet is at risk, and just as no one nation is responsible for climate change, no one nation can address it alone,” Obama said after the meeting.

Leaders gathered to discuss climate change against the backdrop of a Group of Eight summit and a December deadline to agree in Copenhagen on a new treaty to curb greenhouse-gas emissions. The difficulty of crafting an accord in five months was on display as the industrialized nations and emerging economies remained at odds over most proposals for sharing burdens to stem dangerous climate shifts.

“We have not yet crossed the gulf of distrust between the developed and developing countries,” said Kim Carstensen, head of the World Wildlife Federation’s global climate initiative, in an interview.

While today’s climate agreement isn’t “ideal,” it marks a “positive evolution,” Brazil’s Foreign Minister Celso Amorim said in a briefing.

The U.S.’s special envoy on climate change, Todd Stern, said the pledge by developing countries to take new steps to control climate change is “significant and meaningful.”

Among those more critical of the outcome was Teresa Ribera, Spain’s secretary of state for climate change.

‘Copenhagen Is Threatened’

“We still haven’t defined the path” to be taken to forge a treaty’’ by December, Ribera said today in an interview. “Copenhagen is threatened.”

The promises were outlined today in a joint declaration of the Major Economies Forum, a 17-member group made up of the world’s largest greenhouse-gas emitters.

“We’ve made a good start,” Obama said. He called the talks “candid” and said further progress “will not be easy.”

Developing and industrialized nations have been in a stalemate over how to proceed in replacing the Kyoto Protocol. That 1997 accord, aimed at controlling climate change, was rejected by the U.S. in part because it doesn’t require emerging economies such as China and India to make emissions cuts. Kyoto’s emissions limits for developed nations expire in 2012.

China, India Balked

China, India and other developing nations with the largest emissions balked this week at a draft declaration of the Major Economies Forum that called for a global goal to cut emissions 50 percent by 2050, according to one of the people familiar with the talks. The language was removed from the text.

The participating countries agreed to “work between now and Copenhagen” to “identify a global goal for substantially reducing global emissions by 2050,” according to the final document.

“Progress toward the global goal would be regularly reviewed,” the text says.

Rejecting adoption of a 50 percent reduction was a setback for industrialized nations trying to lay the groundwork for negotiations later this year in Copenhagen.

The G-8 agreed for the first time yesterday to cut their greenhouse gas emissions 80 percent by 2050 and repeated a call for developing countries to accept a global reduction target of 50 percent by mid-century.

Poorer Nations

The developing countries blame industrialized nations for the bulk of heat-trapping gases, such as carbon dioxide, that most scientists say are advancing climate change. Poorer nations want so-called mature economies such as the U.S. and Japan to reduce their pollution 40 percent by 2020 and provide more financing and technology to developing nations to reduce gases.

The nations agreed for the first time to limit warming since industrialization began to 2 degrees Celsius (3.6 Fahrenheit), according to the text. The G-8 also agreed to a 2- degree limit.

“The two degrees is an important step forward,” said Jake Schmidt, international climate policy director at the Natural Resources Defense Council in Washington. “You effectively have the world’s biggest emitters committing at the highest level to move their collective efforts towards avoiding the worst impacts of global warming.”

Many of the industrialized countries, including the U.S., Russia, Japan and Canada, hadn’t previously endorsed such action, Schmidt said. A number of developing nations had either publicly backed the idea or “implicitly supported it prior to the meeting,” he said.

$400 Million Reference

The document dropped a reference from an earlier draft to $400 million in funding by industrialized nations to help poor countries switch to a low-carbon economy. The provision was stripped from the final G-8 statement on climate that was released yesterday.

“It’s my understanding from an official from a developing country that the amount was so small” that the emerging economies didn’t want to appear to endorse it by including the amount in the text, said Alden Meyer, director of policy at the Union of Concerned Scientists, a Washington-based advocacy group.

The countries of the Major Economies Forum removed an earlier reference to emissions peaking by 2020. This was also taken out of yesterday’s G-8 agreement.

---With reporting by Flavia Krause-Jackson in L’Aquila, Italy. Editors: Todd White, Larry Liebert

To contact the reporters on this story: Kim Chipman in L’Aquila, Italy, at kchipman@bloomberg.net; Alex Morales in London at amorales2@bloomberg.net.

Last Updated: July 9, 2009 15:04 EDT