26 June 2007The Independent
Even though yesterday's remarkable downpours seem very much out of the ordinary, no scientist is going to say that in themselves they prove the climate is changing. There have always been floods; there have always been severe floods. The natural variability of the climate has always included extremes. However, if the predictions of supercomputer climate models are correct, rain of the unusual intensity experienced in many places yesterday is going to become a much more commonplace feature of the weather in Britain as the century progresses.
Furthermore, yesterday's torrential storms do fit an emerging pattern of "extreme events" in rainfall in Europe which is consistent with predictions of climate change, and which has started to become clear since the Millennium.
The first of these was the rainfall of autumn 2000 in the UK, which led to the widespread inundation of riverside towns such as Shrewsbury, York and Lewes, on a scale which had hardly ever been witnessed before. The respected independent meteorologist Philip Eden later examined the rainfall in south-east England over the period 1 April 2000 to 1 April 2001 and found that it had been 39 per cent above the long-term average. He calculated the "return period" of such a meteorological event - that is, how often it could be expected to recur - and found the answer to be 750 years.
In August 2002 it was the turn of central Europe; unprecedented rainfall burst river banks and flooded great cities such as Prague and Dresden, in the continent's costliest-ever weather-related event. Then in August 2004, the drama was repeated, on a small scale, in the Cornish village of Boscastle, when a month's rain fell in two hours and turned a stream you could jump over into a torrent that was carrying away cars.
To conclude that yesterday's downpours fit into this pattern is not unreasonable; Mr Eden was at his calculating again yesterday, finding that the rainfall has been 140 per cent above normal for June, and in the wettest area of all, the north-east of England, 281 per cent above average for the time of year.
Of course, it may all be the climate's natural variability, but Britain's insurance industry is not convinced of that. The Association of British Insurers reckons that by 2080, global warming may have increased the annual cost of flooding in Britain by almost fifteen-fold, with potential losses of £22bn per annum.
That water mill may look charming, but you might want to think before buying it.
