Is the changing climate pushing Britain's weather to new and violent extremes?

Theories

In its nature, it was a straightforward Atlantic depression. It formed over the ocean, 1,000 miles to the west of the British Isles on the polar front, where the cold air from the north meets the warm air from the tropics, and then it swung towards us bringing its winds and rain, just as dozens of Atlantic lows do every year.

In its nature, it was a straightforward Atlantic depression. It formed over the ocean, 1,000 miles to the west of the British Isles on the polar front, where the cold air from the north meets the warm air from the tropics, and then it swung towards us bringing its winds and rain, just as dozens of Atlantic lows do every year.

But the storm that yesterday wrecked transport and power supplies on an unprecedented scale across the country was not normal in its intensity: its winds were the fiercest to hit Britain for more than 10 years, reaching 97mph, and gusting at up to 90mph over much of the South. Its barometric pressure fell to 951 millibars, making it the deepest low recorded in the country in October, deeper even than the depression that brought us the Great Storm of October 1987.

And it is a sign of things to come, according to a growing body of opinion which sees in such elemental violence the signs of man-made global climate change.

Storm 2000 was not quite as fierce as the blow of 13 years ago, nor as the "Burns Night" storm of January 1990, both of which featured winds exceeding 100mph, but it was very much of the same order: it was an extreme weather event. It was the sort of phenomenon that once was expected to hit us at very infrequent intervals - 200 years was cited in the case of the 1987 storm.

Now we have had three such remarkable tempests in just 13 years, and yesterday ministers, government officials and scientists were looking at the fact that extreme events are one of the main types of weather phenomena expected to increase with the onset of global warming - and drawing their own conclusions.

"It is a pattern which is beginning to develop," said the Environment minister Michael Meacher. "We have to realise that this almost certainly has climate change as a contributory cause."

Surveying the devastation, the Environment Agency's head of operations, Archie Robertson, said: "We are seeing increasing evidence that climate change may be impacting on our environment."

Scientists are more cautious - but by no means dismissive - of the possible link between yesterday's storm and a climate which has begun to heat up and become more unstable because of the increasing concentration of industrial gases in the atmosphere which retain more of the sun's heat.

"You have to choose your words carefully," said the Met Office's spokesman, Andy Yeatman. "We still can't say that last night's storm was directly due to climate change. If you look at the difference between weather and climate, weather is the violent fluctuations from day to day which take place between the upper and lower boundaries which form climate. Most things that are happening are still taking place between these boundaries.

"What we think will happen is that we will start to see more and more events that hit on the boundaries, and more and more that take place outside them. But when you get winds of 100mph, you are getting close to the boundaries. We don't get much higher speeds than that.

"If you can't say it was due to climate change, you can say that this storm was consistent with climate change predictions."

Furthermore, straightforward high winds were not the only extreme weather event of the last couple of days. Part of the south coast seems to be turning into Britain's tornado alley. A twister struck Selsey in West Sussex yesterday morning, wrecking a caravan park (which had been evacuated because of the gale warnings), only a few miles from Bognor Regis, where another tornado struck on Saturday.

It was the second tornado to hit Selsey in less than two years: one which struck in January 1998 caused severe damage to houses, while at nearby Pagham yet another twister damaged houses in September 1999.

An increase in the number of tornadoes would also be consistent with predictions of global warming, meteorologists say, but why so many should strike one area of Britain's south coast is not clear.

"The air is potentially ready for tornadoes a lot of the time," said Dr Terence Meaden, of the Tornado and Storm Research Organisation. "They are almost there, but not quite happening. There has to be an extra factor that is the trigger, and this seems to be maritime humidity, the humid air you get along the south coast. Tornadoes typically start out at sea, hit the coast, and run in for about a mile, damaging buildings."

But this does not explain why there should be more tornadoes in Sussex than in Cornwall, for example.

The Met Office, which is still sensitive to the accusation that it failed to alert people to the 1987 Great Storm - the television weatherman Michael Fish famously said there was no hurricane on the way - is pleased that the multi-million pound Cray supercomputer at its headquarters in Bracknell, Berkshire, anticipated the development of yesterday's storm days ahead of it forming.

The depression began to take shape on Saturday, but the computer had predicted it - and the Met Office had begun to put out warnings - on Thursday.

The storm has put a violent cap on a miserable year's weather for Britain. It has been the wettest September and October for 25 years, while summer sunshine has been way down - it was below average in June, July and September.

But it has a political import as well, with Britain's environmental community seizing on it as one more pressing reason for world governments to agree on tougher action against global warming at a meeting in The Hague next month to strengthen the Kyoto climate change treaty.

The gales and storms are just a taste of things to come, according to Friends of the Earth (FoE). The campaign group says that extreme weather worldwide in the last three months has included storms in Taiwan, Brazil and Canada, floods in Bangladesh, Japan, Vietnam and India, fires in the United States, Italy and the Balkans and droughts in Burundi, Croatia, Kenya and Iran.

Roger Higman, senior climate change campaigner at FoE, said: "Dangerous climate change is already happening. The storms and floods we are now seeing will get more frequent and more severe. We desperately need cuts in the use of coal, oil and gas to prevent the worst forecasts coming true."