RUSUTSU, Japan — World leaders today endorsed halving world emissions of greenhouse gases by 2050, edging forward in the battle against global warming but stopping short of tough, nearer-term targets.

The Group of Eight leading industrial nations — the United States, Japan, Russia, Germany, France, Britain, Canada and Italy — also called on all major economies to join together to stem the potentially dangerous rise in world temperatures.

“This global challenge can only be met by a global response, in particular, by the contributions from all major economies,” the G-8 said in a joint, five-page communique.

The G-8 last year at a summit in Germany pledged to consider the 2050 target, and this year’s Japanese hosts had hoped to solidify that commitment at the meeting in Toyako, northern Japan.

The G-8 has been under pressure to secure commitments by wealthy nations to push forward stalled U.N.-led talks on forging a new accord to battle global warming by the end of next year.

The new accord would succeed the troubled Kyoto Protocol when its first phase expires in 2012.

The United States hailed the agreement as substantial progress, and a top European Union official called it a “new, shared vision” by wealthy nations on climate.

The leaders of major developing countries such as China, India, Mexico, Brazil and South Africa said they expect the G-8 to take the lead and provide more aid to the developing world to help it cope with climate change.

The leaders, including Chinese President Hu Jintao and Indian Prime Minister Manmohan Singh, said the industrial nations must lead because they have the economic strength to adopt sweeping changes.

They called on the G-8 countries to reduce their greenhouse gas emissions by up to 45 percent by 2012, compared with their 1990 levels, and by up to 95 percent by 2050.

Today’s statement, however, addressed total world emissions rather than just those produced by wealthy countries, and critics attacked it for failing to go much beyond the G-8 statement last year.

The communique also did not set a base year from which emissions would be cut.

“It falls dangerously short of what is needed to protect people and nature from climate change,” said Kim Carstensen, director of the World Wildlife Fund’s Global Climate Initiative.

Environmentalists have argued that the 50 percent reduction target is insufficient, and have clamored for ambitious targets for countries to cut emissions by 2020. Japan itself has set a national target for cutting emissions by between 60 percent and 80 percent by 2050, but has not set a midterm goal.

Shorter-term targets have been much more difficult to reach consensus on. The United States, for instance, has argued that meeting a Europe-supported goal of reducing emissions by between 25 and 40 percent by 2020 is unrealistic.

In a nod to such disagreements, Japanese Prime Minister Yasuo Fukuda — the summit host — said the G-8 countries would set individual targets, and he did not mention a range. The statement also said that the issue would be discussed in talks on Monday among the 17-member Major Economies Meeting, a U.S.-led group working on climate change.

“The G-8 will implement aggressive midterm total emission reduction targets on a country-by-country basis,” he said.

The White House quickly hailed the agreement and said it was a validation of Bush’s global warming policy.

The G-8 acknowledged that it alone cannot effectively address climate change — that contributions from all major economies are required — a position Bush has argued repeatedly, said Dan Price, the president’s deputy national security adviser for international economic affairs.

The agreement also urged nations to set high goals for energy efficiency, promote clean energy and technologies and mobilize financing to help poor nations cut their own emissions and grapple with the effects of warming.

Scientists say urgent action is needed to make greenhouse gas emissions fall after peaking within the next 15 years, to limit the increase in global temperatures to under 3.6 degrees Fahrenheit. Temperatures beyond that could trigger the worst effects of warming, such as melting ice sheets and extreme weather.

The U.N.-led climate talks have been plagued by divisions. Quickly developing nations have urged wealthy countries to take the first, toughest steps. The United States, Japan and others, meanwhile, say they want to hear what up-and-coming economies like China are willing to do.

European Commission President Jose Manuel Barroso said the agreement constituted a “new, shared vision by the major economies” that would support the U.N.-led effort on a new global warming accord.

“This is a strong signal to citizens around the world,” he said in a statement, calling for a renewed push behind the U.N. talks, which aim to conclude a new pact at a meeting in Copenhagen, Denmark, in December 2009.

German Chancellor Angela Merkel called the agreement a “major step forward” from the climate deal reached in Germany.

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Associated Press writers Malcolm Foster and Steve Gutterman in Rusutsu, Eric Talmadge in Sapporo and Deb Riechmann in Toyako contributed to this report.