July 8 (Bloomberg) -- Leaders of the Group of Eight nations backed for the first time an 80 percent cut in greenhouse gases by industrialized countries by mid-century and pledged to prevent temperatures from rising more than 2 degrees Celsius.

Their declaration, released at today’s G-8 meeting in L’Aquila, Italy, incorporates a previous commitment to reduce emissions worldwide 50 percent by 2050, according to the statement provided by Italian officials.

The U.S. and other countries previously declined to support calls to limit the average global temperature rise to 2 degrees Celsius (3.6 degrees Fahrenheit) from pre-industrial levels. While White House officials called today’s commitment a significant step forward on climate change, this week’s meetings hit an impasse when China and India refused to support the reductions of 50 percent and 80 percent in a separate declaration.

“The movement out of the G-8 raises the bar a little bit, but obviously it’s a disappointment that you don’t have agreement from developing countries,” Alden Meyer, director of policy at the Union of Concerned Scientists, a Washington-based advocacy group, said in an interview today from the meeting.

The G-8 agreement calls on emerging economies to make “quantifiable” reductions in emissions compared with “business as usual.”

Developing Countries

International talks for a new climate treaty have long been stymied by disagreement over what developing countries such as China, the world’s largest emitter of greenhouse-gases, should do to reduce emissions and to what extent so-called mature economies should help poorer countries deal with climate change.

Along with this week’s G-8 meeting, leaders from the Major Economies Forum, made up of the world’s 17 biggest polluters, including the U.S. and European Union, will meet in L’Aquila tomorrow in an attempt to lay the groundwork for a new global climate treaty.

U.S. President Barack Obama will lead that session in his first major appearance in international climate-change negotiations.

The United Nations-led talks are set to culminate in Copenhagen in December, when almost 200 countries will gather. They will face pressure to meet the UN’s 2009 deadline for a new, more stringent accord aimed at lowering worldwide greenhouse-gas pollution.

‘Significant Contribution’

Today’s agreement from the G-8, coupled with the declaration to be released by the Major Economies Forum, will make a “significant contribution to addressing the issues as part of the Copenhagen negotiations,” Michael Froman, Obama’s representative at the meetings, said today in a news briefing.

The G-8’s declaration includes a goal of reducing global emissions by at least 50 percent by 2050, with developed countries cutting their greenhouse gases in aggregate by 80 percent or more by 2050 compared with 1990 or “more recent years,” according to the document.

Leaders of the biggest industrialized economies dropped from their declaration support for $400 million in funding to help poor countries switch to a low-carbon economy.

The G-8 countries also removed language from prior draft documents calling for emissions to peak by 2020.

To contact the reporter on this story: Kim Chipman in L’Aquila, Italy, at kchipman@bloomberg.net

Last Updated: July 8, 2009 15:18 EDT