KOBE, Japan - The world is losing momentum in the battle against global warming, the U.N. climate chief warned yesterday, urging environmental ministers from wealthy nations to revive the effort by setting clear targets for reducing greenhouse gases.

The ministers gathered in the western Japanese city of Kobe for a three-day meeting as evidence mounted that rising world temperatures have been taking a toll on the Earth at a faster rate than previously forecast.

The officials from the Group of Eight countries, joined by representatives from other countries, including China, and other organizations, were to lay the foundations for the G8 summit in northern Japan in July.

U.N. climate chief Yvo de Boer told the Associated Press on the sidelines that he was concerned about stalling momentum behind international talks to forge a global warming pact by December 2009 to succeed the Kyoto Protocol. Its first phase ends in 2012.

"Much of the enthusiasm and ambition that we saw in Bali with the launch of negotiations doesn't seem to be present," he said, referring to a meeting on the Indonesian resort island in December, when some 190 countries decided on a timetable for talks on the new climate pact.

De Boer cited a recently announced U.S. climate plan that would allow an increase in emissions, Canada's indication that it will not meet its obligations under the Kyoto agreement, and European industry's skepticism about the EU goal of cutting emissions by 20 percent below 1990 levels by 2020.

To rejuvenate the talks, G8 countries - the United States, Japan, Russia, Britain, Germany, France, Italy and Canada - need to decide on midterm targets for reducing carbon emissions by 2020, make a clearer commitment to helping poorer nations deal with climate change, and form a dialogue with top developing countries such as China to run parallel with the U.N.-led talks, he said.

"Certainly my expectation is that . . . the G8 leaders will now really take things to the next level, and I think need to take it to the next level, with December 2009 being just around the corner," de Boer said.

The ministers heard yesterday from environmentalists and business leaders before moving behind closed doors.

Environmentalists urged quick action to stem the effects of the rise in world temperatures, which scientists say threaten to drive species to extinction, worsen floods and droughts, and thwart economic development.

The rapid melting of ice in the Arctic, increasing crop damage and other effects show the multiplying effects of higher temperatures, said Bill Hare, of the Potsdam Institute for Climate Impact Research.