World leaders meeting in Germany have agreed to pursue "substantial" cuts in greenhouse gas emissions and integrate U.S. climate plans within the established U.N. process, an EU source said.
"They agreed on the need for substantial reductions in greenhouse gas emissions," the source told Reuters.
The United States resisted attempts by German Chancellor Angela Merkel, host of the Group of Eight (G8) summit, to set a firm goal for cuts needed to fight dangerous climate change.
But the EU source said that in the final G8 text, leaders would acknowledge the desire of the European Union, Canada and Japan to cut emissions by at least 50% by 2050 -- in line with Merkel's stated target.
Earlier, U.S. President George W. Bush sought to calm tensions with Moscow ahead of a highly anticipated face-to-face meeting with Russia's Vladimir Putin at the summit.
"I repeat Russia's not a threat, they're not a military threat, they're not something that we ought to be hyperventilating about," Bush said. "What we ought to be doing is figuring out ways to work together."
Security remains tight around the summit venue, a luxury hotel in the small seaside town of Heiligendamm.
On Thursday morning police power boats chased down several smaller Greenpeace craft trying to break through the security cordon, ramming one and dumping its occupants into the Baltic.
At a morning session focused on economic issues, Merkel sat between Bush and Putin, who have exchanged public barbs on U.S. missile shield plans in the run-up to the summit.
The two presidents, smiling and looking relaxed, have not met face-to-face since before Putin launched a verbal attack on the Bush administration in February, accusing it of trying to force its will on the world and become its "single master."
Bush said he would reiterate to Putin his proposal to have Russia send generals and scientists to the United States to reassure them on his plans to put a radar system in the Czech Republic and interceptor missiles in Poland.
Washington says the shield is intended as a defense against "rogue" states like Iran and North Korea and has urged Russia to cooperate. Moscow, which suspects it could be outfitted with attack missiles or used for spying, has rejected the overtures.
As leaders met in an elegant 19th century hotel in Heiligendamm -- a resort in the former east which has struggled to recover from the ravages of the communist era -- relations between Russia and the West are at a post-Cold War low.
The missile shield is not the only issue dividing Russia, the United States and fellow G8 members Britain, France, Germany, Italy, Canada and Japan.