G8 leaders and developing nations remain divided on emissions cuts
World leaders have proclaimed a "shared vision" on climate change, but failed to bridge differences between rich and emerging nations on curbing emissions.
Concluding a summit in northern Japan, leaders from the G8 and developing countries said "deep cuts" in greenhouse gas emissions were needed.
China and other emerging powers declined to endorse specific targets.
The three-day summit on Hokkaido island also discussed Zimbabwe, and the global rise in food and energy prices.
UN Secretary General Ban Ki-moon had called on the G8 to tackle the "interconnected challenges" of soaring food costs, development, and climate change.
On the third and final day of the summit, the G8 and eight developing countries issued a statement calling global warming "one of the great global challenges of our time".
We, the leaders of the world's major economies, both developed and developing, commit to combat climate change in accordance with our common but differentiated responsibilities
G8 statement on climate
But it stopped short of urging numerical targets reducing greenhouse emissions.
"Leaders of the world's major economies, both developed and developing, commit to combat climate change in accordance with our common but differentiated responsibilities and respective capabilities," it said.
India and China dismissed the rich nations' call for them to halve emissions by 2050.
The BBC's Roger Harrabin at the summit says China felt that emerging economies were being implicitly asked to take responsibility for a problem caused mainly so far by the West.
the G8 - which includes the UK, US, Canada, France, Germany, Italy, Japan and Russia - restated its "vision" of halving harmful emissions by 2050.
But Mexico, Brazil, China, India and South Africa challenged developed countries to cut their greenhouse emissions by more than 80% by 2050.
Japanese Prime Minister Yasuo Fukuda said the G8 leaders had demonstrated they were serious about tackling climate change.
"It is the very first time ever that leaders of the major economies have got down to vigorous discussions on a broad range of climate-change-related issues, and I believe that the leaders have shown strong political will," he said.