RUSUTSU, Japan  Rich nations and emerging powers on Wednesday declared climate change “one of the great global challenges of our time.” But they set no short-term goals for reducing greenhouse gas emissions, with the largest developing countries demanding more action by wealthy nations before moving.

The declaration grew out of an unprecedented meeting that brought together 16 nations, rich and poor, and the European Union on global warming. The session, organized by President Bush, took place here on the northernmost Japanese island of Hokkaido, where leaders of the Group of 8 pledged Tuesday to “move toward a carbon-free society” by seeking to halve worldwide emissions of heat-trapping gases by 2050.

But a group of the largest emerging economies, led by India and China, now the leading source of greenhouse gases, refused to sign on to that goal. They are holding out until rich nations like the United States take more aggressive steps to cut pollution over the next decade.

That fissure prevented the 16 countries from “reaching any meaningful understanding” in the special session on Wednesday, said Alden Meyer, who is tracking the talks for the Union of Concerned Scientists. Others said the declaration was important at least symbolically and could set a course for action. Phillip E. Clapp, of the Pew Environment Group, said the declaration helped prepare the way for the next American president to grapple with climate change when the United Nations negotiates a binding treaty in Copenhagen in 2009.