There have been deep divisions over how to curb global emissions World leaders have agreed to set a global target of cutting carbon emissions by at least 50% by 2050 in an effort to tackle global warming.
Japan's Prime Minister Yasuo Fukuda, who is hosting a summit of the Group of Eight industrialised nations, announced the deal after all-night negotiations.
Last year's G8 summit pledged only to "seriously consider" the cuts.
The leaders have also expressed serious concerns about the threat posed to the global economy by soaring oil prices.
But the leaders said they remained positive about the long-term resilience of their economies, so long as countries resisted the introduction of trade barriers.
The BBC's Bridget Kendall, who is at the summit, says no explanation was offered for the underlying causes for the high oil and food prices, nor concrete solutions offered on how to bring prices down.
The summit is taking place in Toyako, on the Japanese island of Hokkaido.
Leaders from the G8 nations - Britain, Canada, France, Germany, Italy, Japan, Russia and the United States - are being joined by counterparts from some 15 other countries.
In a joint statement, the G8 leaders said they would work with nearly 200 other UN member states - who have signed up to the convention on climate change - to adopt a goal of halving greenhouse gas emissions by 2050.
The G8 said that mid-term targets and national plans would be needed to achieve their aim.
Climate change has been one of the stickiest issues tackled by the G8 leaders, with divisions over what targets should be set and what would be expected of developing countries.
Speaking at the summit, the Japanese prime minister said he would call for the co-operation of China and India in cutting emissions when they join the meeting on Wednesday.
An unnamed US official said the agreement represented "substantial progress" on last year's summit pledge.
Copyright Speakers Corner 2017