Record heat raises climate fears

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Sun worshippers took to Brighton beach in their hundreds yesterday, where the temperature hit 18.1C. In Kinlochewe on the far north-west coast of Scotland, it was a balmy 22.4C.

Just four days before Hallowe'en, Britain was enjoying the warmest 27 October since records began in 1880.

As the UK basked in the freakish heat, it seemed almost churlish to seek an explanation. But these days, in the shadow of global warming, extreme weather patterns come with a health warning attached. Why was it so warm?

The weather experts explained that the mini-heatwave was the result of a large area of high pressure over southeastern Europe and low pressure well to the west of Ireland.

Sandwiched in between these two weather systems was Britain, which happily found itself right in the way of a warm southerly breeze blowing directly from the hot sands of north Africa. The dryness of the air was explained by it coming from the continent rather than from the Atlantic. The Scottish glens enjoyed the added benefit of a meteorological phenomenon known as the Fone effect, when air warms even further after descending from higher ground.

Is this yet more evidence of climate change? Was this the sort of October day Britain might expect in a world where global warming has become reality?

The Prince of Wales said yesterday that climate change was one of the greatest problems facing man. Meanwhile, the chief scientist, Sir David King, reiterated his belief that global warming was a greater threat than terrorism.

Are we to believe that an unusually warm and sunny day in late October is a portent of something more worrying that a bomb on the London Underground?

Global warming sceptics may scoff at the idea but the reality is that a pattern of extreme weather events is beginning to provide hard evidence that the climate of the world is changing.

A single warm day at the end of October proves nothing but a series of warm days, or weeks or years can be used to build up a long-term pattern of climate change.

"You can't use one event to prove or disprove climate change," said Simon Brown, a specialist in extreme weather at the Met Office's Hadley Centre in Exeter, Devon.

"It's only by looking long enough that you can say that these sort of weather events are getting more frequent or more extreme," Dr Brown said.

A wider analysis of meteorological data is now pointing to a clear pattern of changing climate.

The 10 hottest years on record - and these are based on average global temperature - have occurred in the past 14 years. The previous four years have all been hotter than any other year except for 1998.

The exceptionally hot, dry summer of 2003 is estimated to have resulted in about 35,000 extra deaths in Western Europe. A statistical analysis has shown that global warming has made such summers about four times more likely than in a world where the climate is stable.

Another statistical analysis of the hottest summer night each year for 50 years has shown that the global average temperature of such evenings has increased by about 1C.

"We can only explain this by putting man-made emissions of carbon dioxide into the equations. But this is for 50 years worth of data. For a single day you cannot say anything substantial," Dr Brown said.

Just as yesterday's exceptional weather cannot be used to prove climate change, neither can an exceptionally cold autumn day be used to prove the opposite.

However, a series of warm days and years is consistent with the pattern expected from a world where carbon dioxide levels are more than a third higher than before we began burning fossil fuel.

A warm day in late October is unusual but it has to be seen in a wider context.

"It's consistent with the picture we're beginning to see of rising average temperatures but we can't prove it mathematically. It's conjecture," Dr Brown explained.

It all comes down to the difference between the weather, which is what we experience on a day-to-day basis, and climate, which is a measure of the average weather over many decades, centuries or even millennia.

"Climate is the weather you might expect, whereas weather is what you actually get. The climate may predict a wet, windy winter but you might get a dry, frosty one," Dr Brown said.

Such careful distinctions were the last thing on the minds of the youngsters surfing in the waters around Tynemouth, Tyne and Wear, yesterday. For one day only, it was summer again.

The Prince of Wales yesterday identified climate change as the "greatest challenge to face man" in a BBC interview, and demanded faster action to fight global warming.

He said that his generation owed it to future generations to do more.

"We should be treating the issue of climate change and global warming with a far greater degree of priority than is happening now," he said.

He added: "Again, if you think about your... and my grandchildren, this is what worries me. I don't want them - if I'm still alive by then - to say, 'Why didn't you do something about it, when you could have done'; this is the point."