Extra high sea levels pose threat to British coastline

EXTRA HIGH sea levels, due to occur once every century, could be happening once every three years by 2030 - according to environmental scientists at the University of East Anglia - so increasing the risk of severe flooding.

Friends of the Earth commissioned the three scientists to analyse the likely impact of rising sea levels, caused by global warming, on Britain's coastline. As increasing quantities of heat are trapped in the atmosphere because of pollution, the oceans are expected to expand slightly.

According to the Intergovernmental Panel on Climate Change (IPCC), an international group of experts brought together by the United Nations, the average sea level rise across the world will probably be less than 1 foot (0.3 metres) by 2030 and about 2 feet by the end of the next century.

But along the south and east coasts of England the land is already sinking because the earth's crust is still adjusting to the retreat of the glaciers at the end of the last ice age. This subsidence, which is thought to be happening at around 1mm per year, will exacerbate the sea level rise.

The Friends of the Earth report warns of the potential threat to beaches, golf courses, marinas and nature reserves as well as seaside towns. Using the IPCC estimates, Dr John Barkham, Frances MacGuire and Sam Jones of the university's School of Environmental Sciences predicted that by 2030 sea levels in the south-east would be between 28 and 84 centimetres - 11 and 33 inches - higher.

They then examined historical records for the maximum sea levels recorded each year at 25 British ports. For each, they considered the extreme high water level which could be expected to happen, on average, once a century - and how frequently this level would occur given a 'best estimate' of likely sea level rise.

They concluded that by 2030 the '100-year high water level' could be expected more often than once every five years at Milford Haven in Dyfed, Cardiff, Newlyn in Cornwall, Portland, Newhaven and Colchester. Newhaven headed the list, with a 100- year high level expected once every three years in 40 years' time.

The findings are likely to be challenged, partly because they are based on historical records. Superimposing estimates of sea level rises on this data may give invalid conclusions.

Scientists are also uncertain about how sea levels will respond to any change in climate in the next century. Global warming could lead to a big increase in snowfall on Greenland and in the Antarctic; this would lock up more of the earth's water as ice and lower sea levels.

But there is the possibility of the ice sheets responding to temperature increases by sliding into the sea, causing rises in sea levels of more than 100 feet.