It was the final G-8 summit of Bush's presidency and he said "significant progress" had been made on fighting global warming when the leaders agreed to slash greenhouse gas emissions in half by 2050 and to insist that developing nations be part of any new international agreement.
"In order to address climate change, all major economies must be at the table, and that's what took place," Bush said before boarding Air Force One to return to Washington.
The "major economies" are the world's 16 largest-emitting nations, accounting for 80 percent of the world's air pollution. The expanded meeting that included all of them was the first time their leaders had sat down together for climate discussions.
But it ended with only a vague reference in their final declaration to a long-term goal for reducing global emissions and a pledge for rich and poor countries to work together. Only a few of the emerging powers - Indonesia, Australia and South Korea - agreed to back the 50 percent by 2050 reduction target.
The five main developing nations - China, India, Brazil, Mexico and South Africa, who together represent 42 percent of the world's population - issued a statement explaining their split with the G-8 over its emissions-reduction goals. They said they rejected the notion that all should share in the 50-percent target, since it is wealthier countries that have created most of the environmental damage up to now.
"It is essential that developed countries take the lead in achieving ambitious and absolute greenhouse gas emissions reductions," said the statement.
Chinese President Hu Jintao went a step further in separate remarks. While acknowledging that developing nations must act, he said "developed countries should make explicit commitments to continue to take the lead in emissions reduction."
"China's central task now is to develop the economy and make life better for the people," he said. "... China's per capita emission is relatively low."
Yvo de Boer, who leads United Nations negotiations to forge a new climate change treaty, also challenged Bush's optimistic assessment of the meetings.
"I don't find the outcome very significant," de Boer told The Associated Press in an interview in the Netherlands. He said the target for reducing carbon emissions by 2050 mentioned no base line, was not legally binding and was open to vastly different interpretations.
Bush called the gathering in this resort city on the mountainous northern Japanese island of Hokkaido "very productive" on a range of issues. But he returned home with a mixed bag, reflecting a president with fewer than 200 days left in his term, low approval ratings at home and waning influence abroad.
The G-8 countries - the U.S., Japan, Germany, Britain, France, Italy and Canada - pledged to follow through on commitments made earlier to increase global economic aid to Africa by $50 billion from the 2005 level by 2010, with half of it to go to Africa. Bush had complained that G-8 partners were not living up to a pledge they originally made at the 2006 summit in Gleneagles, Scotland.
He also won support for a deal for using international food reserves to help the poorest countries cope with soaring grain prices.
And summit partners heeded Bush's plea to do more to help fight AIDS, malaria and infectious childhood diseases, particularly in Africa.
Bush also played a big role in getting a strong G-8 statement designed to increase pressure on negotiators to resume long-stalled global talks to ease trade barriers.
On Zimbabwe, G-8 participants rejected the legitimacy of Robert Mugabe's presidential election in what has been branded a sham by the international community. They proposed a special UN envoy and said they would take financial and other steps against those "responsible for violence." But the statement stopped short of endorsing the U.S.-sponsored resolution now before the U.N. Security Council that proposes to sanction Zimbabwe and freeze the assets of Mugabe.
The summit participants did little that would help bring down record oil and gasoline prices in the short or immediate-term, nor to support the tumbling U.S. dollar, a six-year slide that has hurt most of their economies as well. Then again, Bush didn't ask for their help in propping up the dollar, despite repeating his support-for-a-strong-dollar mantra.
Bush also struck out a few times on the sidelines of the summit.
He was rebuffed by Russia's new president, Dmitry Medvedev, in his efforts to win Moscow's support - or at least neutrality - on his proposal to base parts of a U.S. missile-defense system in nations of Eastern Europe that used to be part of the Soviet bloc.
They met for an hour and vowed closer cooperation on a range of issues. But Medvedev later told reporters that his chat with Bush yielded "no particular progress" on issues dividing the countries, particularly the missile shield. "We will be studying countermeasures," if the U.S. goes ahead with such plans, Medvedev said without elaborating.
"We will continue to have a dialogue with the Russians on this matter," said White House national security spokesman Gordon Johndroe.
Bush did score a few wins in the climate-control debate. In addition to drawing reluctant developing nations into the process, he got fellow G-8 participants to pledge to annually dedicate $10 billion to technology research and development.
