Scotland's unique built heritage is facing "catastrophic" and irreversible damage from the effects of climate change "within three to five years" if no action is taken, a groundbreaking conference in Edinburgh will be told later this month.
Hosted by the Scottish Traditional Skills Training Centre (STSTC), the event is billed by its organisers as "the most significant gathering of conservation and climate experts assembled ever held in Scotland".
Its aim is to spell out the extent of the damage caused by recent changes in weather patterns, mainly persistently high rainfall, and to spread awareness of the crisis facing Scotland's world-renowned wealth of historical properties and natural landscapes.
According to the Historic Environment Advisory Council for Scotland the historical environment of Scotland is of huge importance to the Scottish economy, directly supporting around 41,000 jobs within the conservation sector, construction industry and tourism, and is estimated to contribute more than £2.3 billion per year to the economy.
Scotland has around 47,600 buildings listed for their historical and architectural interest by Historic Scotland, around 50% of them classified category A or B, denoting international or national importance.
Dr Maureen Young, a conservation scientist for the Scottish Government heritage agency Historic Scotland, one of the keynote speakers at the international event, said the more persistent and heavier rainfall patterns of recent years threatened "severe surface deterioration on many older buildings within three-five years". The worst affected, she said, were those on the east coast.
Sites such as Dundee, Montrose and Arbroath, which are "built of softer red sandstone", were at particular risk. However, she said it was still possible to save some of these sites if protective measures were radically stepped up: "If you keep the buildings [watertight], then essentially they remain pretty stable."
Young pointed to recent research by academics at Queen's University Belfast that suggested increased rainfall was leading to faster decay of building stone, by increasing levels of moisture within the stone, preventing it from periodically drying out, as intended by the original architects and engineers.
She added that air pollution worsened this detrimental effect on older buildings by allowing sodium to enter the stone. At even greater risk, Dr Young added, were historic coastal sites, such as the preserved neolithic village Skara Brae, the Unesco World Heritage Site in Orkney which, ironically, is believed by some experts to have been abandoned around 2500BC when an earlier phase of climate change caused temperatures to drop.
As well as being subject to the same damage from ever-increasing amounts of rainfall, coastal sites are also facing an increase in coastal erosion because of changes in sea levels which Young says could rise by "20 or 30 centimetres" in the next 10 years.
These sites are also more vulnerable to the "catastrophic impacts" caused by the growing turbulence of the Scottish winter: "You could lose a whole site in one big storm, potentially," she said.
Marc Ellington, executive director of STSTC, said that the ravages of climate change on Scotland's historic buildings had been evident for "about a decade", but that tackling the issue had been complicated by the ideological polarisation of the debate surrounding the environment.
"Until recently there were a lot of people who thought climate change was bunkum and it became a political issue, but it simply cannot be denied. We have never, ever seen the pattern of change that is currently emerging and there is a very strong consensus amidst science authorities on changes in the weather and climate, and also the melting of the polar ice caps. There is no doubt that we in Scotland are seeing a very different type of weather than we have ever seen before."
Ellington said that the climate conditions that prevailed when much of Scotland's most distinctive historical building no longer applied.
"We know from the records we have that a lot of our 18th-century buildings such as the New Town of Edinburgh were built in a period of relative drought, which explains why, when we get these intense bouts of rainfall, it can cause real problems with the stone, with the roofs and with the rainware. They simply weren't designed for it, or for the continuous damp conditions which account for much of the biological growth on masonry."
Ellington will use the two-day event held at Hopetoun House on July 22-23 to stress the importance of "finding a way to ensure that our best buildings from the past are able to exist as they are at present in the future."