The text also says the 17-member Major Economies Forum (MEF) will seek to double public investments in low-carbon technology by 2015 and boost funding from both public and private sources as well as from carbon markets to fight global warming.

The draft was put forward by the United States and Mexico at talks in Mexico this week, without reaching accord before a MEF summit on July 9. U.S. President Barack Obama launched the MEF to help toward a new U.N. climate pact due in December.

"We support an aspirational global goal of reducing global emissions by 50 percent by 2050, with developed countries reducing emissions by at least 80 percent by 2050," according to the draft text, obtained by Reuters and dated June 22.

Last year, industrialized nations in the Group of Eight agreed at a summit in Japan to a "vision" of halving world greenhouse gases by 2050 to help avert ever more droughts, floods, heatwaves and rising sea levels.

Developing countries including China, India and Brazil did not adopt that 2050 goal in Japan, arguing that the rich first have to set tough 2020 cuts for themselves. The MEF summit will be on the sidelines of this year's G8 summit in Italy.