TOYAKO, Japan -- World leaders embraced for the first time on Tuesday an ambitious but nonbinding goal of slashing greenhouse-gas emissions in half by midcentury to stave off global warming. Unimpressed environmentalists called the effort too slow and too uncertain.
Leaders of some of the world's richest nations praised the agreement, which endorsed President Bush's insistence that fast-developing countries like China and India join in the effort. But one environmental critic suggested that by 2050 those leaders would be forgotten and "the world will be cooked."
Details were scant in the statement issued by the Group of Eight. Some could become clearer Wednesday when China, India and six other fast-developing nations sit down with the Group of Eight industrial nations -- the United States, Japan, Germany, Britain, Germany, Russia, Italy and Canada -- to discuss climate change strategies.
The G-8 did not specify a base year for its proposed 50 percent cut, and the actual emissions reductions and the effect on the environment could vary hugely depending on what is eventually decided. Reductions from 2005 levels, for instance, would be far less than from 1990 levels, as in the Kyoto Protocol on global warming.
Still, U.N. Secretary-General Ban Ki-moon said it was essential to set a long-term goal for global greenhouse emissions by 2050. He said the world cannot afford to wait until 2009, when nations are planning to try to conclude a new global warming treaty to succeed the Kyoto Protocol when its first phase expires in 2012.
The United States has never ratified the Kyoto treaty, with Bush complaining that it puts too much of a burden on the U.S. and other developed countries to reduce emissions while developing giants such as China and India are given a freer rein to pollute even as they vigorously compete with America around the world.
Bush will leave office next January, and both major candidates to succeed him have said they are willing to go further in cutting back American emissions.
The G-8 statement, released by host Prime Minister Yasuo Fukuda in an announcement with the verdant hills of northern Japan behind him, solidified a pledge made at the last summit in Germany a year ago to seriously consider such a long-term target.
But the move fell far short of demands by some developing countries and environmentalists pushing for deeper cuts by 2050 and a firm signal from wealthy countries on what they are willing to do on the much tougher midterm goal of cutting emissions by 2020.
"To be meaningful and credible, a long-term goal must have a base year, it must be underpinned by ambitious midterm targets and actions," said Marthinus van Schalkwyk, South African Minister of Environmental Affairs and Tourism.
"As it is expressed in the G-8 statement, the long-term goal is an empty slogan."
Said Atonio Hill, spokesman for Oxfam International, a confederation of organizations that work on climate change, poverty and other causes: "At this rate, by 2050 the world will be cooked and the G-8 leaders will be long forgotten. The G-8's endorsement of a tepid 50-by-50 climate goal leaves us with a 50-50 chance of a climate meltdown."
However, U.S. officials hailed the declaration as a major step forward, "substantial progress from last year," in the words of Dan Price, the president's deputy national security adviser for international economic affairs.
U.S. officials said they expected agreement on cooperation to be reached at Wednesday's expanded meeting, even if painted with a broad brush. But the wording of the G-8 statement left a lot of wiggle room for the fast-growing economies to ease the potential burden.
And while the development appeared to be a victory for Bush, it could turn out to be mostly a symbolic one once the final statement from what the G-8 is calling a "Major Economies Meeting" is issued on Wednesday.
The decision on climate change split some of the differences between Bush and other G-8 members.
Japan and European members have been pressing for setting a long-term goal of a 50 percent reduction in global greenhouse emissions by 2050. Other members, including the U.S., Russia and Canada, have been less enthusiastic about such a target. Bush has long said that China and India and other big, growing economies must share in the pain in reaching such a goal.
The Europeans have pushed harder for rich countries to reinvigorate talks by making unilateral commitments. Germany, for instance, has pledged to cut emissions by 20 percent by 2020, and by 30 percent if other countries join the effort.
Still, some European leaders praised the Tuesday accord.
"This is a clear advance, compared with the shaky agreement from the previous year," said German Chancellor Angela Merkel.
Jim Connaughton, chairman of the White House Council on Environmental Quality, said, "It has always been the case that a long-term goal is one that must be shared."
"So what the G-8 has offered today is a G-8 view of what that goal could be and should be, but that can only occur with the agreement of all the other parties," he added, referring to nearly 200 countries involved in U.N. talks.
The agreement -- and the praise it elicited among European countries usually more ambitious on climate change -- reflected a desire to avoid shortcomings of the 1997 Kyoto accord.
Kyoto, while considered by many a worthy first step, has also been seen as flawed by its failure to commit developing countries like China to emissions controls, prompting the U.S. refusal to ratify it. In addition, many countries with reduction commitments, such as Japan and Canada, are falling seriously behind.