It is possible that the deal struck yesterday between G8 countries will lift the burden from the US of being the villain of global warming. But not likely.

The determination of Angela Merkel, the German Chancellor, to make climate change the target of her summit distracted attention from President Putin’s weekend outburst and put the heat on President Bush.

Merkel got part of what she wanted: the US’s agreement to join a pact that will try to set limits for emissions. But that is because the appetite in the US for taking action was already much greater than its critics allowed. They also fail to credit the obstacles that the US Constitution puts in the way of signing pacts, which European countries appear to regard not just as easy steps to take, but as proof of morality.

You cannot plausibly (although many do) accuse US politicians of lack of interest in global warming. If only because it seems easier to tackle than Iraq, there is no other debate. The new Democrat-controlled Congress has held almost daily hearings in the Senate and House of Representatives. Forty states have put forward more than 300 Bills this year. The Supreme Court ruled in April that the Environmental Protection Agency could not claim that it lacked the authority to treat greenhouse gases as pollution, a decision which could have huge implications for factories and cars. Meanwhile, Bush has called for cuts of a fifth of the US’s petrol use by 2017, as well as demanding rises in cars’ fuel economy.

This is not nothing, to appropriate one of the pithy, alliterative judgments which are the only valuable legacy of Donald Rumsfeld, former Secretary of Defence. But it also shows the complexity of the process by which the US takes decisions. It is lengthier than that of European governments, run by leaders who are less fettered than a US president. To portray it as pure unwillingness is wrong. Germany presents the closest parallel, and the fragile governing coalition is a much greater curb on Merkel than her lectures to the G8 imply. She has no game plan for broaching the notion of new nuclear power stations to that coalition, however much the sums show that Germany must consider it soon.

The structure of the US economy gives it good reason to be wary of emissions curbs. It has not failed to make that point, but has often seen it drowned out in gibes at its wasteful taste for sports utility vehicles.

Those tastes are real, but the demands of the sheer size of the territory show up in the attached table – the miles travelled per head are more than double those in Britain.

These US reflexes – the desire to “do something”, the fear of being shackled by rules crafted to fit smaller European economies, and the vow not to let any leader damage citizens’ lives – were present in a hearing by the House Committee on Science and Technology in March.

It was the best and worst of US government: examining the issues in limitless detail, but ricocheting between fears of the immeasurable, whether China or offending God’s will for the planet. Their prime witness, Al Gore (addressed by one member as “a thinker, a personality and now a movie star”) was lyrical about Europe’s virtues but skimped discussion of the costs.

Committee members, between the compliments, made that point trenchantly, and they were right to do so.

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