Q. There seems to have been more and more flooding in recent years? Is that really the case?
A. There does seem to have been a substantial increase in flooding in Britain compared with recent historical records, beginning with the floods in the Midlands of Easter 1998, affecting towns from Northampton to Leamington Spa, which took everyone by surprise and in which five people died. Subsequently, there have been a series of unusually severe flooding events, such as the autumn of 2000, which were the heaviest floods on record, and prompted John Prescott, then Environment Secretary, to proclaim that they were a warning about climate change, and the floods of 2007, which came from the wettest summer since rainfall records began in 1766. Every summer since then has been wet by normal standards, and last summer was the wettest since 1912.
Q Is this being caused by climate change?
A. There is an increasingly strong belief among some climate scientists that the substantially heavier rainfall we are witnessing is related to a changing climate. Although it is very difficult to ascribe a single rainfall event to global warming, no matter how heavy it is, because the natural variability of the weather is infinite, it is certainly possible to say that extreme rainfall is consistent with predictions of what global warming will bring. Computer models of the future climate of Britain show far more intense rainfall in the years to come.
Q. But there seems to be so much flooding. Is it all from increased rainfall?
A. In essence yes, because more intense rainstorms are throwing up a new issue – the problem of “surface water”. In the past flooding was either coastal – when the sea invaded the land, as in the great East Anglia flood in January 1953 – or fluvial, when a river burst its banks. Now we have a new kind, surface water flooding, which occurs when the rain is so great that the drains are simply overwhelmed, cannot cope and back up. The flooding in Hull and Doncaster in June 2007 was of this type – and a man died. About a third of the flooding of the last few days has been caused by surface water, made worse by the fact that many drains are blocked by fallen leaves.