Flood-ravaged Britain is suffering from a wholly new type of civil emergency, it is clear today: a disaster caused by 21st-century weather. This weather is different from anything that has gone before. The floods it has caused, which have left more than a third of a million people without drinking water, nearly 50,000 people without power, thousands more people homeless and caused more than £2bn worth of damage - and are still not over - have no precedent in modern British history.

Nothing in the past hundred years, in terms of flooding caused by rainfall, has been as bad. According to the Environment Agency, even the previous worst case, the extensive floods of spring 1947, which were aggravated by the vast snow melt that followed an exceptionally hard winter, has been surpassed. "We have not seen flooding of this magnitude before," said the agency yesterday. "The benchmark was 1947, and this has already exceeded it." And the 1947 floods were said to have been the worst for 200 years.

Most remarkable of all is the fact that the astonishing picture the nation is now witnessing - whole towns cut off, gigantic areas underwater, mass evacuations, infrastructure paralysed and grotesquely swollen rivers, from the Severn and the Thames downwards not even at their peaks yet - has all been caused by a single day's rainfall. A month's worth and more in an hour. It is obvious that the Government and the civil powers, from Gordon Brown down to the emergency services, are struggling to cope, not only with the sheer physical scale of the disaster itself, but with the very concept of it. It is entirely unfamiliar. It is new. Yet it is exactly what has been forecast for the past decade and more.

No one can yet attribute the flood events of the past week, or indeed, those of June, when Yorkshire suffered what Gloucestershire and Worcestershire are suffering now - again from one single day's rainfall - directly to global warming. All climates have a natural variability which includes exceptional occurrences.

But the catastrophic "extreme rainfall events" of the summer of 2007, on 24 June and 20 July, are entirely consistent with repeated predictions of what climate change will bring. It is nearly 10 years since the scientists of the UK Climate Impacts Programme first gave their detailed forecast of what global warming had in store for Britain in the 21st century - and high up on the list was rainfall, increasing both in frequency and intensity.

This was thought most likely to happen in winter, with summers predicted to be hotter and dryer. But yesterday Peter Stott of the Met Office's Hadley Centre for Climate Prediction and Research, an author of a new scientific paper linking increases in rainfall to climate change, commented: "It is possible under climate change that there could be an increase of extreme rainfall even under general drying."

The paper by Dr Stott and other authors, reported in The Independent yesterday, detects for the first time a "human fingerprint" in rainfall increases in recent decades in the mid-latitudes of the Northern Hemisphere - that is, it finds they were partly caused by global warming, itself caused by emissions of greenhouse gases. The public as a whole appears not to have taken the extreme rainfall predictions on board, thinking of climate change in terms of hotter weather. But the science community has been fully aware of it, and has steadily reinforced the warnings.

One of the most important came from a group of experts commissioned to look at the risks by the Chief Scientific Adviser, Sir David King, under the Government's Foresight Programme, in 2004. Their report, Future Flooding, said that unless precautions were taken, more severe floods brought about by climate change could massively increase the number of people and the amount of property at risk. Yet once again, this hardly penetrated the public consciousness. Amidst all the news of communities being overwhelmed by water yesterday, one very significant announcement, from Gordon Brown and the Secretary of State for the Environment, Hilary Benn, was that the Government is setting up an independent inquiry to look at the flood events of June and July.

Its report will be immensely important and may prove a milestone in terms of the British public's appreciation of the reality of climate change. It will doubtless focus on the key problem in terms of flood response - there is no one minister, or other person, in overall charge - but it may also take a view of the disaster in terms of global warming, and may well come to the conclusion that we are already witnessing the future. The floods of 2007 may eventually be regarded as a wake-up call to the warming climate's rapidly approaching effects.

Nobody saw them coming. But that appears to be the way of a changing climate. In April 1989 Margaret Thatcher, then Prime Minister, gave her Cabinet a seminar on global warming at No 10 and one of the speakers was the scientist and green guru James Lovelock. A reporter asked him afterwards what would be the first signs of global warming. He replied: "Surprises." Asked to explain, he said: "The hurricane of October 1987 was a surprise, wasn't it? There'll be more." The floods of 2007 were a surprise as well, and if Dr Lovelock is right, there'll be more of them too. Welcome to the weather of the 21st century.

The flood of 1947
The Great Flood of 1947, the previous worst inundation caused by rainfall in Britain, swamped almost all of the rivers in the South, Midlands and the North-east, submerged 700,000 acres of land and caused an estimated £4bn worth of damage (in today's money).

The deluge was predominantly caused by the rapid thaw of snow and ice that had covered much of England after a particularly long and cold winter. The weather patterns that caused the thaw also caused a number of torrential downpours, exacerbating the flooding. The timing could not have been worse; Britain was still recovering from the war. Rationing was harsh, deprivation widespread and the economy was teetering. What made the catastrophe even more unfortunate was that it occurred before the era of flood insurance.

The flooding started across the South, from Somerset to Kent, as many rivers broke their banks. By 14 March, parts of west and north-east London had been submerged. The next day, the river Thames overflowed its banks at Caversham, near Reading, and around the Lea Valley to the east of London. By the end of the month, an estimated 100 000 homes had been flooded, hundreds of thousands of people displaced and the year's crops largely wiped out.
(By Michael McCarthy, The Independent, 24/07/2007)