Environment ministers from top industrial countries have called for an agreement on cutting greenhouse gas emissions in half by 2050.
Ministers want developed nations to take the lead in battling global warming.
The Group of Eight nations, aiming at preparing for action on climate change at the G8 summit in Japan in July, also acknowledged calls for mid-term emissions reduction targets for 2020.
The three-day meetings of G8 ministers -- from Japan, the US, Germany, France, Italy, Canada, Britain and Russia -- and observer countries in Kobe, Japan, also strove to revive momentum for wider UN-led talks on a new global warming pact.
"The major outcome was on climate change. We strongly expressed the will to come to agreement at Toyako so we can halve emissions by 2050," Japanese Environment Minister Ichiro Kamoshita said. "Advanced nations should show leadership to reach this goal."
A statement cited the need for global gas emissions to peak within the next 10 to 20 years, and it called on developing countries with rapidly expanding greenhouse gas emissions to work to curb the rate of increase.
While signalling the need for midterm targets, the ministers made only an indirect mention of a UN scientific finding that rich countries should make reductions of between 25% and 40% by 2020 to avoid the worst effects of warming.
European nations, the UN climate chief and environmentalists had clamoured in Kobe for progress toward such a reduction pledge by G8 countries, arguing that failure could endanger the UN talks, which face a December 2009 deadline.
"Without a mandatory midterm target for developing countries, it will be very difficult to get agreement" by that deadline, said Matthias Machnig, the delegate from Germany.
The European Union has pledged a 20% emissions reduction by 2020 and has offered to raise it to 30% if other nations sign on. The US, however, has not committed to a mid-term goal, demanding commitments from top developing countries such as China first. Japan has also not yet set a 2020 target.
