Tom Levitt, MSN Environment Editor

Q&A: why Britain's coasts are under threat

We answer some of the key questions about coastal flooding.

Why are our coasts under threat?

In short because of rising sea levels and stronger storm surges. Global mean sea level has increased by 1.0 to 1.5mm per year during the 20th century. Best estimates predict a rise of around 4mm per year over the 21st century.

More on climate change from the UKCIP (UK Climate Impacts Programme).

Why are sea levels rising?

Global warming. As the temperature of the atmosphere increases, ice on land will melt and run into the sea. However, according to the Environment Agency, a greater influence is likely to come from the thermal expansion of the oceans as they warm. Sea level rise by thermal expansion will continue for many centuries after the climate has been stabilised because of the large heat capacity of the ocean.

More on sea level rises from the Environment Agency.

How is coastal flooding different to inland flooding?

The difference between inland flooding and coastal flooding is that it never stops on the coast. The tide keeps coming in everyday. So once the water level has risen and old river banks broken there really is no way back.

Who is responsible for sea defences?

The Environment Agency. While they are open to the idea of communities taking responsibility for their own sea defences (at their own cost) they have indicated that they may object if it has knock-on implications for other stretches of coastline.

What is being done to improve sea defences?

The government has committed £602m for spending on coastal and inland flood defence programmes in 2008. That annual figure will rise to £800m by 2010/11.

In response to the new predictions for sea level rises and more intense storms, the government agency responsible for flood defences, the Environment Agency, is drawing up new Shoreline Management Plans (SMPs) for the whole of England and Wales. These will detail how they would protect each stretch of coastline for the next 100 years.

However, if the cost of improving the sea defences is not considerably less than the economic cost of what would be flooded then the government will not upgrade them. “We are looking for a five to one benefit so for every pound we spend we expect to get £5 worth of benefit back,” said Helen Wakeham, flood risk advisor at the Environment Agency.

How can I find out more about the flood risk in my area?

See the Environment Agency's flood risk map.

Could insurance companies refuse to cover vulnerable homes?

At the moment insurance companies are still covering homes at risk from flooding – but with higher premiums in some cases. However, there was a recent warning from the Association of British Insurers (ABI) that this may not last.

"Insurance companies are there to protect people against uncertain events but we are at a point where flooding has become a certain risk," ABI policy advisor Swenja Surminski told delegates at the Environment Agency’s annual conference. "You will get insurance today but in the future i am not so sure. It is unlikely that everyone will be protected from flooding."

Back to the coastal flooding page

Back to the Coastal Flooding in Britain section

Map: see which towns will be hit first by rising sea levels

Video: a community threatened by the sea

Debate: should we protect whatever the cost?