MORE THAN 10,000 of the most important ancient and historical sites around Scotland's coastline are at risk of being destroyed by the storms and rising sea levels that will come with global warming.

Sites in jeopardy include the neolithic settlement of Skara Brae on Orkney and the prehistoric ruins at Jarlshof on Shetland. Others under threat range from Viking burial boats to Iron Age brochs and Mesolithic middens.

New surveys for Historic Scotland reveal that the remains of communities up to 9000 years old could be lost for ever due to accelerating coastal erosion.

The potential loss is incalculable and has alarmed experts. "This is a uniquely valuable and totally irreplaceable part of the nation's cultural heritage, with much still to teach us about our past," said Tom Dawson, an archaeologist at the University of St Andrews.

"While people argue over whether climate change is leading to sea level rise and an increase in stormy weather, the coast continues to erode. Although wildlife and the natural habitat may be able to recover, ancient sites will be destroyed forever, and the remnants of our ancestors will be lost."

Dawson manages a group called Scottish Coastal Archaeology and the Problem of Erosion (Scape), which was set up in 2001 to protect ancient shoreline sites. With the help of local Shorewatch' groups across the country, Scape has been investigating the status of the sites.

So far some 30% of Scotland's coastline has been surveyed, discovering 11,500 archaeological sites of which 3500 are judged to be at risk of erosion. According to Dawson, that suggests that more than 10,000 sites around the whole coast are likely to be at risk.

The results of the surveys have been summarised in a report by Scape to Historic Scotland, which has not yet been published. But Dawson is due to unveil his findings at a major conference on climate change and the historic environment in Stirling on Tuesday.

Many of the archaeological sites are concentrated on Orkney, Shetland, the Western Isles and parts of the west coast, which are known to be particularly vulnerable to storms.

Others can be found around all the major estuaries, including the Clyde and the Forth.

Many sites have yet to be excavated and properly studied. Others are iconic and well-known remains defended by old and eroding seawalls, such as Skara Brae, Jarlshof, the Broch of Gurness on Orkney and Lochranza Castle on the Isle of Arran.

Dawson accepted that it would be impossible to save all the sites. But he stressed how important it was to try to map, study and preserve as many as possible in order of priority.

"It is not all doom and gloom," he said. "By working together, we can rescue information and artefacts from some of the sites before they are destroyed."

A recent example of the damage that can be inflicted by extreme weather was the fierce storm that whipped the Western Isles in January 2005, which tragically claimed the lives of five people from one family when they attempted to drive across a causeway near their home on South Uist.

According to Dawson, the storm washed away up to 20 metres of the coastline in some places. At Baile Sear beach, on the west coast of North Uist, a car park and a picnic area disappeared, leaving a track ending abruptly on the shoreline.

The storm also uncovered a mass of archaeological remains at Baile Sear, including pottery, animal bones, slabs of masonry and an ancient waste dump. In order to try to record what has been revealed before it vanishes in another storm, archaeologists and volunteers have been working extensively there this summer.

Teams discovered two buildings, a structure containing several small rooms and a remarkably preserved Iron Age wheelhouse, probably built around 2000 years ago.

They also found that, since the 2005 storm, the beach had retreated by five metres and walls had shrunk by up to a metre in height.

Elsewhere, a Shorewatch group has been drawing and photographing the remains of a Pictish building which is being eroded at Sandwick on Unst in Shetland. There are plans for another "adopt-a-monument" team to excavate an ancient Bronze Age structure at risk from the sea on the island of Bressay in Shetland.

Tuesday's conference on climate change is being organised by the Historic Environment Advisory Council for Scotland (HEACS), which advises ministers. It will hear evidence of the widespread dangers posed by worsening weather. "Archaeological sites, ancient monuments and historic buildings are all threatened by climate change," said HEACS secretary, Olwyn Owen. "But they also have much to teach us. This is not the first time that Scotland's inhabitants have had to adapt to change."

A recent study of Brodick Castle on Arran by the Centre for Sustainable Heritage at University College London found that its walls were being penetrated and damaged by driving rain. The problem was partly due to inadequate guttering.

Mike Corfield, the former chief scientist of English Heritage, argued that penetrating rain and other threats were going to get worse with global warming. "I personally think that this is a very serious problem that we are going to have to address," he told the Sunday Herald.

As well as the risks to coastal sites and historic buildings, Corfield was worried about valuable artefacts buried underground. Alterations in the chemistry of the soil triggered by climate change could accelerate corrosion, he suggested.

Ingvar Maxwell, director of technical conservation with Historic Scotland, agreed that climate change was a potential threat. "Water is well recognised as the engine of decay," he said.

There were half a million houses in Scotland built before 1919, he pointed out, many from sandstone which is particularly vulnerable to damage from moisture penetration. The country also has more than 47,000 listed buildings and 8000 scheduled ancient monuments.

Maxwell has a team investigating whether climate change will accelerate the decay process. "We are talking about possible impacts on all building materials and on all Scotland's built heritage," he said.