Leading article: Boiling point

Welcome to the greenhouse. This is what, increasingly, it is going to be like. For while no reputable scientist will confidently attribute the devastating heatwave now gripping much of the northern hemisphere to global warming on the strength of just one summer, this is precisely what research has predicted, as climate change takes hold. Most people are already finding it unpleasant, making fools of commentators who have looked fondly forward to living in a Cotswold Chiantishire. And it is going to get a lot worse. Climate change is an 18-rated horror film. This is its PG-rated trailer.

The awesome truth is that we are the last generation to enjoy the kind of climate that allowed civilisation to germinate, grow and flourish since the start of settled agriculture 11,000 years ago. Peering back over hundreds of thousands of years, deciphering natural records laid down in Greenland and Antarctic ice, scientists can find no other period remotely as stable and hospitable. Human history has taken place during a climatic ceasefire in normally hostile conditions. Like terrorists or rogue states - and in defiance of all warnings - we are breaking it.

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The really frightening thing is how fast the change is happening. Just 11 years ago, the world's leading scientists - reporting for the official Intergovernmental Panel on Climate Change - struggled to agree that "on balance" global warming was taking place. Now its effects are plain for anyone to see who is not irredeemably prejudiced, obtusely stupid or George Bush (or, possibly, all three at once).

The Greenland and Antarctic ice sheets are melting , and only last week we exclusively reported how the vast and seemingly indestructible Amazonian rainforest may be fast approaching a tipping point that would lead to its turning to desert. The world's faltering attempts to negotiate even the slightest reduction in the pollution causing all this - due to resume in Nairobi in November - do not even begin to keep up.

The one good sign is that the world's publics are getting the message, and beginning to apply pressure. Hurricane Katrina's devastation of New Orleans transformed US opinion overnight, ensuring that whoever succeeds the benighted Bush will finally address the issue. Public alarm over the Amazon - catalysed by an extraordinary visit by the Eastern Orthodox patriarch and other religious leaders this month - last week forced Brazilian firms to halt felling the rainforest in order to grow soya. And maybe this heatwave will prove to be a boiling point, if not the tipping point, for public outrage. But it is all getting desperately urgent. A scientific consensus is growing that there is only a decade left in which to act to save the climate. The heat really is on.