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Last Updated: Thursday, 19 August, 2004, 17:57 GMT 18:57 UK
Floods 'to become more frequent'
John Hammond
Broadcast Meteorologist, BBC Weather Centre

Clear-up operations continue in Boscastle, Cornwall.
Summers will be drier, but flash floods are expected to increase
The recent flash floods have raised concerns over the possible repercussions of global warming on the European climate. John Hammond, a BBC meteorologist, looks at possible scenarios.

Heavy rain and flash flooding have been dominating the UK headlines in recent days. Boscastle in Cornwall was the first to suffer earlier this week, with Glen Ogle north of Lochearnhead, Scotland, affected on Wednesday.

Boscastle suffered devastating floods when heavy and thundery downpours developed across north Cornwall, giving around 75mm of rain in just a few hours.

A combination of heavy rain and local topography meant that a river through the village broke its banks, and a raging torrent of water swept through the village, causing devastation to everything in its path.

Climate change

Heavy rain across Scotland caused major problems at Glen Ogle on Wednesday. Hours of torrential rain caused numerous landslides in the area, with people having to be rescued from their cars by RAF helicopters.

Sea horse
A sea horse found in the Thames indicates the river is getting warmer
Such weather events are often described as "freak conditions", but just how unusual is it to have torrential rain and flooding during August?

Taking a look back at the month of August in recent years, such rainfall events are not that uncommon.

In 2002, Fylingdales, North Yorkshire, had 115mm of rain in 24 hours. In the same month, there were localised floods in the London area, with some places receiving 60mm of rain in just one hour.

So it appears that we have experienced significant rainfall events at this time of year in previous years, but where does climate change fit into all this?

The European Environment Agency (EEA) recently published a report which examines the impacts of Europe's changing climate.

It suggests that between 1975 and 2001, the annual number of floods events increased.

According to the report, climate change is likely to increase the frequency of extreme flood events, in particular the frequency of flash floods.

Boosting defences

Flash floods occur where torrential rain falls and it cannot be soaked up or drained away. This leads to run-off, with water running over the ground, rather than through it, resulting in flooding.

With indications that flooding events are set to become more common, what is being done in response?

It has been identified that there needs to be a huge increase in the amount of spending on flood defences.

With such freak events becoming more frequent, there are numerous questions being raised as to whether this is evidence of climate change.

The Environment Agency has called for up to 200m more to be spent each year.

It is also in the process of preparing a map of flood risks across the country in 2050, taking account of climate change.

Future scenarios

Barry Gromett of the Met Office explains: "The recent heavy summer rains are certainly in line with one of the scenarios of how climate change could affect our weather in the UK, but isolated events from one year shouldn't be used to confirm or deny the effects of the phenomenon.

"In general terms the number of 'intense' rainfall events during the summer is likely to decrease, but the intensity of the rain on the days that it does so will probably increase.

"Thus episodes of severe flooding may become more frequent, despite a general trend towards drier summer conditions."

So it seems the future holds a number of questions as to how frequent freak weather events and flooding are likely to play a part in our everyday lives.

However, it is just as important to remember that a single weather event is not clear evidence of climate change, and that looking at the longer term picture is essential.

Flood villagers return to homes
19 Aug 04  |  Cornwall
'I've lost my business and my home'
19 Aug 04  |  Cornwall
Crews work on landslides debris
19 Aug 04  |  Scotland


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