Point of no return

He reckons humanity has damaged the environment to such an extent that climate change is now an insolvable problem.

Fortunately, not everybody is in agreement with Lovelock's planetary obituary. Many green campaigners are not convinced the earth's climate has actually reached the point of no return, subscribing to the more optimistic view that there is still a window of opportunity, however small, for humanity to act.

And act we must. Now. More shocking than Lovelock's statement was a letter that appeared in the same newspaper three days later from 14-year-old Isabelle Ellis-Cockcroft, claiming her generation "is being handed a world of climate chaos spiralling out of control".

For Isabelle and millions like her, we have to hope that Lovelock is wrong and we have a little more time. Of course, he may be right and we may have crossed the threshold - but we cannot be certain. That is why it is important to continue developing innovative engineering solutions that help tackle energy use.

One such innovation is Dynamic Demand's proposal for legislation to ensure all domestic refrigerators are fitted with controls that enable them to work in conjunction with the national grid (see News Analysis). This would reduce carbon emissions simply by controlling when a fridge turns itself on and off. Similarly, researchers in Hong Kong are investigating ways to improve comfort in air-conditioned flats so that a proposal to raise the minimum temperature can be implemented.

Of course, we could be expending effort in the wrong cause; climate is notoriously difficult to model and the experts could be wildly wrong, as one reader suggests. (see letters)

The problem is we cannot wait until we are certain what the precise cause is of global warming. If we don't take action now, and global warming is proven to be the direct result of human activity in the future, it will be too late for the climate, too late for humanity and too late to say you're sorry to Isabelle's generation.