ROSTOCK, GERMANY — President Bush presented himself Wednesday as caught in the middle of the international climate debate, fending off allies' calls for mandatory steps to reverse global warming while encouraging major developing nations to join eventual climate negotiations.
The dispute over how to respond to the world's changing climate is emerging as a focal point of the annual Group of 8 summit that began Wednesday night in Heiligendamm, a resort village on the Baltic Sea. The gathering has drawn tens of thousands of protesters to this northeastern corner of Germany.
White House officials predicted Wednesday that Bush would emerge from the three-day summit with an agreement to hold formal negotiations to establish medium- and long-range targets, reaching out more than 40 years, for reducing greenhouse gas emissions. Critics of the president's position argue that voluntary targets are not enough and fixed limits are needed.
Sitting on the grounds of the castle-like Kempinski Grand Hotel, where the summit is being held, Bush told reporters that "the United States can serve as a bridge between some nations who believe that now is the time to come up with a set goal ... and those who are reluctant to participate in the dialogue."
"We all can make major strides, and yet there won't be a reduction until China and India are participants," he said. His comment reflected a view shared by other critics of the 1997 Kyoto Protocol: that its limits on greenhouse gas emissions target the most economically advanced nations while giving the developing world a pass.
Carbon dioxide, given off when fossil fuels are burned, is one of the main greenhouse gases blamed for an increase in global temperatures.
Bush has objected to the central element of a plan proposed by German Chancellor Angela Merkel, the summit host, and supported by most European leaders. Under it, by 2050 participating nations would reduce their emissions to half of what they were in 1990, with the goal of curbing the increase in global temperatures to no more than 3.6 degrees.
As the leaders of Britain, Canada, France, Italy, Japan and Russia joined Bush and Merkel for an informal dinner before the official meetings began today, police used water cannons to turn back demonstrators. At noon, authorities briefly closed the only two checkpoints leading to the area because 6,000 demonstrators were blocking them.
Demonstrators tramped through nearby fields to thwart police efforts to contain them, and pushed toward the 12-foot razor-wired fence establishing an 8-mile perimeter around Heiligendamm.
Police spokeswoman Jessica Wessel told The Times that 166 protesters had been arrested and 16 police officers injured. She said she didn't have information on the extent of the injuries.
White House officials said Bush did not encounter the protesters, who disrupted travel, at times blocking the road to the small airport nearby used by arriving leaders, and that they had no effect on his activities.
Merkel has built the summit around the issues of poverty, particularly in Africa, and climate change.
Speaking during a photo session after lunch with Bush, Merkel hinted at the ongoing disagreement with the president, saying they had "a very good debate" and "there are a few areas here and there" on which they need to continue to work.
Merkel's proposal aims to carry the nations most responsible for greenhouse gas emissions beyond the Kyoto agreement, which expires in 2012. The United States, under the Clinton and Bush administrations, never ratified the pact.
Bush proposed new negotiations a week ago, and has called for greater reliance on technology to reduce the emissions while avoiding specific, internationally mandated restrictions.
This position has drawn protest from environmental organizations. On Tuesday, Larry Schweiger, president and chief executive of the National Wildlife Federation based in Virginia, said, "Rather than embrace Chancellor Angela Merkel's proposal to set mandatory pollution targets, the Bush administration is opting to stall."
National security advisor Stephen J. Hadley predicted that the summit's planned climate change report would find consensus on several key elements, among them recognition that global warming is a problem that needs to be addressed and a focus on a post-Kyoto agreement that would bring the 15 nations responsible for 85% of the world's greenhouse gas emissions to negotiations. The former is a step Bush resisted for some time after taking office; the latter has been a central goal of the administration.
On climate change, Bush found something of an ally in Russia.
Dmitri Peskov, a spokesman for Russian President Vladimir V. Putin, said in a conference call with reporters that the Russians found Bush's proposal putting off specific targets "very pragmatic and interesting."
In a brief session Wednesday evening, Bush met with the musicians Bono and Bob Geldof. Bono issued a statement afterward praising the president, as he has in the past, for U.S. efforts in Africa, in this case for Bush's proposal to spend $30 billion over the next five years on global HIV/AIDS programs.
Christian Retzlaff of The Times' Berlin Bureau contributed to this report.