Leading article: A dangerous seasonal disorder

The countryside is looking rather peculiar this winter. It seems we have a number of unexpected guests for Christmas. Dragonflies, bumblebees and red admiral butterflies, which would normally be killed off by the frost, can still be seen in some parts of the country. Bigger beasts are here too. Swallows and house martins, which normally fly south to Africa at this time of year, are still lingering.

There are other signs that something strange is afoot. Many trees that are normally stripped to their bark at this time of year still retain their leaves. And wild plants such as oxeye daisies, usually a summer spectacle, are in flower.

Some might be tempted to welcome this late blossoming of the natural world as a delightful diversion from the bleakness of this time of year. But these fluctuations should be cause for concern because it is overwhelmingly likely that they are a consequence of global warming. This winter has so far been the warmest in central England since 1659. And the Met Office predicts a 40 per cent chance that temperatures will continue to be above average into next year.

It is impossible to predict the consequences. If there were to be a cold snap early next year, zoologists are unsure of whether the navigation systems of the birds that have lingered would be able to get them to Africa. The question of competition for food is another concern. The early flowering of berries in spring was an unexpected boost for many species of bird. But the same birds could suffer if they are not produced at normal times. In short, we simply do not know how warmer seasons will effect the ecosystem of these islands.

This is a cause for concern in itself. But all this is also evidence that global warming is occurring at a faster rate than many imagined. And it will not only be the natural world adversely effected by climate change. By the middle of this century, millions of people in the most inhospitable regions of the planet could be forced to flee their homes due to flooding and drought. And as the Stern report made clear this year, none of us will be spared the dire economic consequences of a greatly warmer world.

The naturalist, Sir David Attenborough, who was voted Britain's "greatest living icon" in a BBC poll over the weekend, took a long time to be persuaded of the threat posed by climate change. Now he is convinced. And he has issued an apocalyptic warning of what will happen unless we take radical action to reduce our carbon dioxide emissions. These strange winter guests could presage something far more sinister and unwelcome for our planet.