An Ice Age bounce is stemming rising sea; North going up in the world as as south dips.

Byline: Tony Henderson

THE "bouncebackability" of the North East after the last Ice Age will cushion some of the effects of rising sea levels caused by climate change.

A new map produced by Durham University plots the most accurate predictions yet for land uplift and subsidence, and shows that southern Ireland and Wales, and southern and eastern England are continuing to sink, while Tyne and Wear, Northumberland and Scotland are rising.

The coastland map charts the post Ice Age tilt of the UK and Ireland and current relative sea-level changes.

According to the map, the sinking effect in the south could add between 10 and 33% to the projected sea level rises caused by global warming over the next century. Since the end of the last Ice Age 20,000 years ago, land and sea levels around the UK coastline have changed in response to the retreat of the ice sheets.

As the ice melted, the release of this enormous weight resulted in the landmass slowly tilting back up in the north or down in the south.

The "hinge" is located around Teesside, which is regarded as the zero area between rising and sinking.

The Durham team led by Professor Ian Shennan and funded by the Natural Environment Research Council looked at the relationship of peat, sand and clay sediments that have been lifted above sea level or are now submerged below sea level.

The team dated samples to calculate changes in sea levels over thousands of years. Prof Shennan said: "The rate of uplift north of the River Tyne to Scotland increases because the ice sheets there were thicker and heavier.

"The action of the Ice Age on our landmass has been like squeezing a sponge which eventually regains its shape. " Prof Shennan said that the average estimated sea level rise from climate change is 1.4mm a year, but the uplift in the North East would reduce this to just under 1mm. "It is lessening the effect but we are still going to feel it," he said.

Prof Shennan said that another factor which could add to vulnerability to sea level rise was subsidence across the extensive North East coalfield.

He said: "Subsidence and rising sea levels will have implications for people and habitats, and will require action to manage resorts, industrial sites, ports, beaches, salt marshes and wetlands, wildlife and bird migrations."

The map will help decisions on levels of investment needed in long-term planning for sea defences and other coastal structures over the next 100 years or so.

"Changes in our oceans and land uplift and subsidence will continue to have a significant effect on our coastlines this century," said Prof Shennan.

CAPTION(S):

LEVEL TERMS The map from Durham University showing areas of rising and sinking land. Researchers from the university at work, above left.