Leading Article: Stop talking about the weather - do something about it

LIKE A Napoleonic general, the American Vice-President Al Gore had a slice of luck earlier this week. He rushed, with our own John Prescott close behind him, to announce scientific evidence that July had been the hottest month the world had experienced since records began, telling a hastily called press conference: "You don't have to be a scientist to know that it has been dangerously hot this summer."

Happily, Washington did not suffer a downpour minutes after Mr Gore began speaking, for that sort of coincidence is exactly the sort that the (many) Americans sceptical of global warming would deem sufficient to torpedo his argument.

Had he spoken just two weeks ago, Britons would have gazed up at the dismal skies and sneered, "Dangerously hot? Chance would be a fine thing." Even the roasting sunshine that much of Britain experienced last weekend is now giving way again to the usual old grey and damp.

That is the problem with trying to understand global warming. As a species, we are much better at understanding local changes. We do not really move around that much. We can imagine that if migratory birds could talk, they would tell us a lot about the changing conditions they see.

Instead, we see only a tiny sliver of what is happening and can only glimpse what life might be like when the accelerating effects of global warming really take hold. The scenarios include malaria in the Surrey stockbroker belt, while low-lying islands in the Pacific are submerged; or Britain, deprived of the warming Gulf Stream, shivering year-round with freezing temperatures like Newfoundland's, while in other countries farmland turns to desert.

We occasionally spot differences here and there: hasn't it been rainy this summer, aren't the flowers out early this spring? It takes a more subtle understanding of what is going on to realise that if Britain has a wet summer, then that probably does mean that sea temperatures are higher than usual.

As Sir John Houghton, chair of the International Panel on Climate Change, explained last week, most of our weather comes from the Atlantic and, the warmer that is, the more water evaporates from it before falling on us as rain. "Rain is stored energy," he said.

So, American sceptics will ask, why isn't it raining in the Midwest? We do not know - the planet is not so simple that we can put all its vagaries into an equation.

Pulling together the wider picture into a global Gestalt takes a gargantuan scientific effort, and even that is not infallible. On Thursday, two American scientists announced that the satellites used to make some atmospheric measurements were slowly, slowly falling towards the Earth. That, they said, explained why those satellites were suggesting that parts of the troposphere were cooling, instead of - as the computer models suggested - getting warmer.

Yet, America in particular continues to resist calls to limit its production of greenhouse gases and push energy efficiency. The Deputy Prime Minister, John Prescott, deserves credit for constantly pressuring the Americans to take action, though it is noticeable how much easier it is to criticise others' inaction than to take action at home. What price cheap public transport? When will company car subsidies be ended?

Even so, it is the biggest players who can have the biggest effect on this situation. It is odd that while the US preens itself for its global influence in the sphere of human interaction, it has so many people ready to deny that their gas-guzzling cars and the enormous distances that they transport inessential goods could possibly alter the planet's weather. Mr Gore said in his speech, "It is really hard to ignore the fact that something is going on - and that something is global warming." But the real danger is that the immediate issues of American political life - attacks on embassies abroad, inquisitions into presidential fumblings with interns - will keep providing that excuse to ignore reality.

Glued to the television coverage of this trial, or that rescue mission, nobody will notice the weather outside until it is too late.