Expert predicts 'Monsoon Britain'

Prepare for more floods – in ways we are not used to - that’s the message from experts at Durham University who have studied rainfall and river flow patterns over 250 years.

Last summer was the second wettest on record and experts say we must prepare for worse to come.

Professor Stuart Lane, from Durham University’s new Institute of Hazard and Risk, says that after about 30 to 40 less eventful years, we seem to be entering a ‘flood-rich’ period. More flooding is likely over a number of decades.

Prof. Lane, who publishes his research in the current edition of the academic journal Geography, set out to examine the wet summer of 2007 in the light of climate change. His work shows that some of the links made between the summer 2007 floods and climate change were wrong. Our current predictions of climate change for summer should result in weather patterns that were the exact opposite of what actually happened in 2007.

The British summer is a product of the UK’s weather conveyor belt and the progress of the Circumpolar Vortex or ‘jet stream’. This determines whether we have high or low pressure systems over the UK. Usually the jet stream weakens and moves northwards during spring and into summer. This move signals the change from our winter-spring cyclonic weather to more stable weather during the summer. High pressure systems extend from the south allowing warm air to give us our British summer.

In 2007, the jet stream stayed well south of its normal position for June and July, causing low pressure systems to track over the UK, becoming slow moving as they did so. This has happened in summer before, but not to the same degree. Prof. Lane shows that the British summer can often be very wet – about ten per cent of summers are wetter than a normal winter. What we don’t know is whether climate change will make this happen more in the future.

However, in looking at longer rainfall and river flow records, Prof. Lane shows that we have forgotten just how normal flooding in the UK is. He looked at seasonal rainfall and river flow patterns dating back to 1853 which suggest fluctuations between very wet and very dry periods, each lasting for a few years at a time, but also very long periods of a few decades that can be particularly wet or particularly dry.