Members of international relief group Oxfam are dressed as President Bush, Japanese Prime Minister Yasuo Fukuda, French President Nicolas Sarkozy, British Prime Minister Gordon Brown, and German Chancellor Angela Merkel, from left, to show how the ongoing Group of Eight summit has amounted to a holiday.

TOYAKO, Japan — President Bush today hailed the move by G-8 leaders to coalesce behind a broad climate-change strategy, saying in a valedictory to summitry that "significant progress" has been made on global warming.

"In order to address climate change, all major economies must be at the table, and that's what took place today," Bush said. Environmentalists said the summit's broad pledge to work toward slashing greenhouse gas emissions by 50 percent by 2050 did not go far enough.

Still, Bush's position represented quite a progression for a president who in his first term disputed scientists' assertions about global warming. This time, he heartily backed the broad goal stated by his summit partners.

"We made clear, and the other nations agreed, that they must also participate in an ambitious goal," Bush said, "with an interim goal, with interim plans to enable the world to successfully address climate change. And we made significant progress toward a comprehensive approach."

The leaders couldn't agree on additional specific numerical targets, though. And not everybody signed onto the 2050 goal.

In a statement that Bush read to reporters here, he reiterated his position that substantial progress will likely hinge on further development of clean energy technologies. Developing nations, he said, will need assistance so they can become "good stewards of the environment."

The president praised his fellow summit leaders for their work, not only on climate change but also on advancing the so-called Doha Round of negotiations on opening markets to free trade and on their cooperation with U.S. efforts to help poor nations combat disease and food shortages.

The G-8 nations are the U.S., Britain, Germany, France, Italy, Canada, Japan and Russia.

It was Bush's last G-8 summit, and the meeting here, along with his talks on the sidelines of the summit, presented a mixed scorecard for him to take home. Bush saw fellow G-8 leaders essentially embrace his argument that a comprehensive global warming strategy must include participation by developing nations as well as the leading industrialized democracies.