With his popularity low at home and fewer than 200 days left in office, Bush is methodically promoting his issues, seemingly ready to accept incremental progress rather than pursuing eye-catching breakthroughs.
The G-8 endorsed cutting global emissions of greenhouse gases by 50 percent by 2050 and called for emitters to set midterm reduction targets.
The White House quickly hailed the G-8 declaration as a validation of Bush's approach.
"This represents substantial progress from last year," said Dan Price, the president's deputy national security adviser for international economic affairs.
Price said 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.
Price also said the declaration struck here Tuesday reflects the sense the development and deployment of clean technologies in developing nations is crucial -- another thing that Bush has been pushing.
The president long has insisted that major emerging economies like China and India be included in any global plan to cut emissions. Bush scored a small victory in getting the other big-polluting major economy nations to agree to attend a meeting Wednesday on the sidelines of a summit.
It's unclear, however, whether the heads of state at Wednesday's session will "finalize" a long-term goal for reducing global greenhouse gas emissions, as Bush predicted back in September.
Advocates seeking deeper commitments lamented that the countries did set ambitious midterm targets for emissions cuts by 2020.
"At this rate, by 2050 the world will be cooked and the G-8 leaders will be long forgotten," said Antonio Hill, spokesman for Oxfam International, a confederation of organizations that work on climate change, poverty and other causes. "Rather than a breakthrough, the G-8's announcement on 2050 is another stalling tactic," he said.
The G-8 nations are the United States, Japan, Russia, Britain, Germany, France, Italy and Canada.
European Commission President Jose Manuel Barroso said the G-8's agreement would support stalled U.N.-led efforts to craft a new climate change accord at a meeting in Copenhagen, Denmark, in December 2009.
"This is a strong signal to citizens around the world," he said in a statement.
Also at the summit, Bush asked G-8 nations to make good on the aid pledges they made to Africa in 2005.
The G-8 has delivered on only about 14 percent of its commitment to date. The G-8 now for the first time will release reports offering a country-by-country, disease-by-disease account of how the nations are doing. Still, that small move toward accountability is small potatoes if the leaders don't return home and write checks to Africa.
The G-8 leaders also rejected the legitimacy of Robert Mugabe's election in Zimbabwe. The leaders agreed to send a United Nations envoy to help resolve the crisis and promised to take financial and other measures against those responsible for the violence and intimidation that prompted the opposition candidate to pull out of the race with Mugabe. But there was no mention of U.N. sanctions, as the U.S. has urged.
British Prime Minister Gordon Brown called it "the strongest possible statement." "The whole international community is now not prepared to accept an illegitimate government and want sanction there," he said.
Bush is logging only small steps forward on other issues, too.
North Korea revealed secrets about its arsenal of bomb fuel and destroyed part of its atomic factory on television recently in exchange for economic and political concessions from the United States. It was an encouraging sign that the secretive communist country may give up its bombs altogether and an incremental victory for the Bush administration and other partner nations negotiating with Pyongyang.
The leaders called verification of North Korea's declaration "of utmost importance" and called on Pyongyang to "fully cooperate" with that process.
Still, even Bush acknowledged that it was only one step toward getting North Korea to actually give up its nuclear weapons.
And he is yet to score even any small victories on getting Iran to stop enriching uranium.
The leaders' statement expressed "serious concern" about Iran's failure to meet world demands to stop enriching uranium. But it stressed the need to "resolve the issue innovatively through negotiation."
Tehran's rising influence in the Mideast has emboldened it to reject a recent offer of economic incentives in exchange for giving up its enrichment program. Despite three sets of U.N. sanctions, Iran has not only continued enriching uranium, but says it has expanded its program.
At the summit, Bush also got pushback from Russia over his plan for a missile shield system in Eastern Europe -- something he is keen to advance before he leaves office. Secretary of State Condoleezza Rice was expected to sign an agreement Tuesday to build a radar installation for the missile shield in the Czech Republic, but she has all but ruled out a stop in Poland this week to finalize a deal to have another element of the system built there.
The Poles "are either holding out for a better offer or are worried about signing up for a system that might be delayed under the next administration," says Julianne Smith, Europe program director for the Washington-based Center for Strategic and International Studies.
She added that Russia is very upset to learn the U.S. had started talks with Lithuania just in case. Moscow "finds the idea of placing the system in Lithuania even more alarming," Smith said.
This fight sullied the atmosphere for Bush's talks here with the new Russian president, Dmitry Medvedev.
Just as a G-8 working session got under way, Bush spun around in his chair to shake hands with the new Russian leader. But a few hours later, Medvedev was telling reporters that his hour-long chat with Bush on Tuesday yielded "no particular progress" on issues dividing the countries, such as the missile shield.
"We continue to exchange opinions," he said.