WASHINGTON – President Bush embarked on his third visit of the year to Europe yesterday, with his aides aware that agreements on African aid and debt relief will do little to silence critics of his stance on global warming.

After two visits dominated by diplomatic platitudes, he can expect today to be recast as a political punching bag.

“For Bush, the political risks are bigger than the possible gains,” Philip Gordon of the Brookings Institution said. “The risk is that he has been put back in the category of the global bad guy dragging his feet.”

Over the next 48 hours, American officials will make much of his Africa policy. Even before the recent focus on Africa led to increased pledges of aid and support for debt relief, it was widely acknowledged that Mr. Bush had done far more for the continent than his silver-tongued predecessor President Clinton.

U2’s lead singer, Bono – hardly the natural ally of a conservative Republican president – has hailed his record in fighting AIDS and recently told CBS television: “If in his second term he is as bold in his commitments to Africa as he was in his first, he deserves a place in history in turning the fate of that continent around.”

In fact, while Africa was hardly a priority during Mr. Bush’s first term, several of his advisers have long felt a Christian imperative to ease the continent’s suffering.

As Prime Minister Blair visited Washington last month to press his case on Africa, Mr. Bush’s speechwriter, Michael Gerson, was on the telephone from Africa urging his boss to take dramatic steps to help the continent. Antipoverty campaigners have criticized Mr. Bush’s recent promise to double aid over the next five years as stingy, arguing that much of the commitment is a recycling of old pledges. But with Congress and the American public skeptical of aid without strings attached, Mr. Bush’s pledges, and his support for debt relief, go as far as is feasible.

On global warming, however, Mr. Bush can expect an unremittingly hostile reception, having made clear that there is no prospect of America agreeing to limit emissions.

The administration is keen not to appear insensitive to the environment and is stressing its commitment to renewable energy. Right-wing Web sites picked up yesterday on Mr. Bush’s comment to an ITV broadcaster, Trevor McDonald, that “to a certain extent” climate change was “man-made.”

This was the closest Mr. Bush has come to softening the stance of the White House, which has close links to the oil industry and is deeply skeptical of the science linking greenhouse gases to global warming.

Officials suggested yesterday that the best G-8 diplomats can hope for is a vague “action plan” on climate change, without any specific targets for the reduction of emissions. This might be accompanied by an opaque paragraph referring to a growing consensus about the problem.

Even if Mr. Bush were convinced, he could not sign up to mandatory limits without provoking a rebellion from his own party on Capitol Hill. Under Mr. Clinton, the Senate made clear that signing up to Kyoto was out of the question.

In a hint of a compromise, there is a move to shift the attention to India and China, the world’s second-biggest emitter of greenhouse gases after America. This would appeal to the Bush administration, which has long objected to the way Kyoto imposed tighter limits on developed nations.