RUSUTSU, Japan — The Group of Eight leading industrial nations 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 G-8 countries — America, Japan, Russia, Germany, France, Britain, Canada, and Italy — also called on all major economies to join in the effort 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 on climate.

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

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

Yesterday’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.

Environmentalists criticized the statement for failing to go beyond the G-8 statement last year.

“So little progress after a whole year of Minister meetings and negotiations is not only a wasted opportunity, it falls dangerously short of what is needed to protect people and nature from climate change,” director of the World Wildlife Fund’s Global Climate Initiative Kim Carstensen, said.

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.

“To be meaningful and credible, a long term goal must have a base year, it must be underpinned by ambitious midterm targets and actions,” the South African Minister of Environmental Affairs and Tourism, Marthinus van Schalkwyk, said. “As it is expressed in the G8 statement, the long term goal is an empty slogan.”

Shorter-term targets have been much more difficult to reach consensus on, since they would require nations to act more quickly. America, 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, Japan’s 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, an American-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 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. America, Japan, and others, meanwhile, say they want to hear what up-and-coming economies like China are willing to do.

The 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 at Copenhagen, Denmark, in December 2009.