The Group of Eight major powers agreed Tuesday to at least halve global carbon emissions by 2050 in what leaders hailed as a step forward, but developing nations demanded they do much more.
After two days huddled in the Japanese mountain resort of Toyako, leaders of the world's eight most powerful economies also voiced concern about soaring oil and food prices and pledged to speed up aid to Africa.
But the most contentious issue before them was climate change, with US President George W. Bush standing firm on his stance that developing countries must take action before rich nations would budge.
The leaders of the G8 -- Britain, Canada, France, Germany, Italy, Japan, Russia and the United States -- said they shared a "vision" of reducing emissions by at least 50 percent by 2050.
Last year's summit in Heiligendamm, Germany had agreed only to "seriously consider" cuts in the greenhouse gas emissions blamed for heating up the planet.
"This is a significant step forward from Heiligendamm," German Chancellor Angela Merkel told reporters. "This means that the international community will no longer get off the hook."
The G8 nations also said they would each set their own interim targets for curbing greenhouse gas emissions for a still unspecified amount of time after the Kyoto Protocol's obligations expire in 2012.
But in a nod to Bush, the G8 leaders also called on major developing nations to join them in cutting emissions.
"In our view, and in the view of the leaders in the room, this represents substantial progress from last year," said Dan Price, Bush's assistant for international economic affairs.
Japanese Prime Minister Yasuo Fukuda had pleaded for this year's summit not to backtrack on earlier pledges on global warming, which UN scientists warn could put entire species at risk unless it is curbed by later this century.
"It's been a long road getting here. We had some very tough negotiations," Fukuda told reporters.
But the G8 leaders can expect another difficult round of talks Wednesday when they are joined by leaders of the developing world.
Chinese President Hu Jintao, Indian Prime Minister Manmohan Singh and three other leaders of developing nations met in the nearby city of Sapporo on Tuesday and urged that rich countries cut emissions by 25 to 40 percent by 2020 from 1990 levels.
Singh and Hu also met and agreed that climate negotiations must be held "in a fair and equitable way which does not affect development and growth in developing countries," Indian Foreign Secretary Shiv Shankar Menon told reporters.
South Africa's environment minister Marthinus van Schalkwyk questioned whether the G8 leaders had truly moved forward.
"We are concerned that it may, in effect, be a regression from what is required to make a meaningful contribution to meeting the challenges of climate change," he said.
The G8 deal was full of ambiguity. Senior Japanese official Koji Tsuruoka said that the long-term goal should be seen as a "political vision" without a clear base year and that it is not legally binding.
French President Nicolas Sarkozy appeared to disagree, saying: "We have reached a binding level. That's real progress."
Environmentalists said the progress was nothing to shout about.
"If after a year's work all you have is a 'shared vision' instead of 'seriously considering,' it's pretty pathetic," said Kim Carstensen, head of the WWF's Global Climate Initiative.
Daniel Mittler, a climate change expert at Greenpeace International, said that "instead of action, the world got flowery words."
"The Texas oilman has once again prevented the G8 from undergoing the energy revolution it needs," Mittler said. "Bush is a lame duck, so who cares what he thinks about 2050?"
The United States is the only major industrial nation to shun the Kyoto Protocol. Bush argues that it is unfair because it makes no demands of growing emerging economies such as China and India.
But both major candidates to succeed Bush, John McCain and Barack Obama, have pledged stronger action on global warming, including forcing domestic industry to cut emissions in the world's largest economy.
The G8 leaders issued a statement warning that soaring oil and food prices pose a "serious challenge" to world economic growth and calling for boosted crude oil production capacity.
"The world economy is now facing uncertainty and downside risks persist," the group said in a joint statement.
In another area of contention, the leaders set a timeframe of five years to commit 60 billion dollars to Africa to help fight AIDS, malaria and tuberculosis.
Delegates said that Britain had pushed for a more ambitious commitment of just a few years, but Canada had initially resisted any timetable.
Agence France-Presse - 7/8/2008 1:06 PM GMT