Increased flooding not a trivial problem

IN his recent letter, Mr Kevin Hill states that pictures of the late Duke of Edinburgh visiting the West Country after the damaging floods of July 1968 proves to him, among other things, ‘we have always had floods and hot summers’.

No hydrologist would disagree with the proposition that rivers have always experienced extremes of flow, but the critical question to ask is whether the frequency and the severity of floods and droughts are changing and, if so, why?

As far as flooding is concerned, recent studies of rivers in the UK and in north-western Europe have clearly shown that floods have generally increased in magnitude by around 10% over the last 50 years as a consequence of rising temperatures caused by human impacts on climate.

A warmer atmosphere has a greater capacity to hold water which, in turn, leads to heavier precipitation and wetter soils that promote higher flood peaks in Britain, especially in the autumn and winter months. In addition, increases in extreme precipitation in north-western Europe are related to the poleward shifts of the subpolar jet and of the associated storm tracks observed since the 1970s, which are considered to be influenced by polar warming.

While I can reassure Mr Hill increased flooding is not going to cause ‘the end of the Earth’, river floods are among the costliest hazards, with annual average losses across the globe estimated at US$104 billion and expected to increase with ongoing climate change. So clearly not a trivial problem for humankind.

Professor Bruce Webb

Devon