Shock warning on sea levels

THE COASTAL map of the Westcountry could be dramatically redrawn by the waves if expert predictions of a rise of up to four metres in sea level become a reality.

It would go far beyond previous expectations that remote and sparsely populated coastal areas would be beyond salvation, and mean that large swathes of towns and even cities could be swallowed up by the English Channel over the next century.

It comes as a senior Government adviser has warned that the country should prepare for a temperature increase of 4C (7F) – well above the 2C level which scientists regard as critical. It would mean that some of the best-known features of Devon and Cornwall could be lost for good, including flora, bird life, butterflies and even the region's treasured beaches.

Phil Dyke, coastal property manager for the National Trust, said alarm bells rang when NASA scientist James Hansen warned that sea levels could rise by four metres over the next century, rather than the widely accepted figure of one metre. The climatologist has been widely quoted as saying that sea levels will rise by "at least a couple" of metres this century, with the largest estimate at four to five metres.

He says the lower figure, agreed by the Intergovernmental Panel on Climate Change (IPCC), fails to properly consider the contribution made by the melting of ice sheets.

Mr Dyke said such an increase would have "major implications" for the Westcountry. He said: "When NASA start saying that sort of stuff, you start thinking 'OK, there's probably something in this'."

He said a gauge at Newlyn, used for recording the rise in sea level for the whole country, had recorded an increase of 20cm over the past 60 years. He said the trend of a rise of three to four centimetres each year was likely to continue for the next two decades – after which it would start to increase "exponentially" because the ice would respond to the increase in the change in temperature.

On top of that, an increase of ferocious storms would have dire consequences, with increasingly powerful waves lashing ever closer onto the shore.

The National Trust, which owns a number of coastal areas around Devon and Cornwall, has carried out a range of studies over recent years.

At St Michael's Mount, a study of historical records shows the window of low tide at which people can walk across the causeway to the island has shrunk from three hours two centuries ago to two hours today. Based on current models, the time slot will be down to an hour in 40 years' time.

And at Mullion, the trust has had to make a tough decision on how best to defend the historic harbour. Instead of spending £6 million on a granite reef with a life span of just 25 years, it has opted to repair storm damage this time, but next time to retreat to a logical point and sacrifice the rest – a pattern which will mean there could be no harbour in 60 years.

Mr Dyke said: "As an organisation we aren't really into change. Our general brief is conservation, and we are used to believing we can hang on to things forever – but we have to accept the reality of the situation."

He said a four-metre sea level rise would leave coastal communities – including estuary cities such as Plymouth – vulnerable. It would mean tough decisions would have to be made about where to spend money on defending communities.

He said: "If there is a rise of four metres, us worrying about Mullion harbour will be totally insignificant. It would have serious implications."

He said the sector was now awaiting a report of the UK Climate Impact Partnership, which is being led by the Exeter-based Met Office. When it is published in November, it will provide a more detailed and comprehensive picture on a range of climate change areas, including sea level rise.

Mr Dyke speculated that comments by Professor Robert Watson, chief scientiofic adviser to the Department for Environment, Food and Rural Affairs, that the UK should prepare for a 4C increase in climate could be paving the way for radical new thinking on the issue.

But Ben Johnstone, South West regional flood risk manager for the Environment Agency, was sceptical about the claim. He said climate change and rising sea levels were "key priorities", which formed the "bedrock" or all flood risk management decisions.

But he added: "While rising sea levels are a huge concern, we consider a four-metre rise to be excessive."

He said the agency works on Government guidance that a one-metre rise is likely over the next century.

"Although this is lower than Professor Hansen is saying, the implications will be felt by everyone who lives here. It's a serious concern and one which must not be ignored," he said.

Yesterday, a spokesman for the Met Office said the one-metre sea level rise estimated for the next century took into account 40cm from the Greenland ice cap and 40cm from Antarctica, as well as 20cm from the thermal expansion of the body of water. He said Mr Hansen's estimate was an "extreme example".

A Defra spokesman said: "Based on the evidence, it is unlikely that changes in ice sheet flows will cause global sea level rise by as much as four metres by 2100. However, much more work needs to be done to fully understand the potential impacts of ice sheet flows to increased sea levels due to climate change."