The shores of Scotland’s Orkney Islands are dotted with ruins that date to the Stone Age. But after enduring for millennia, these archaeological sites – along with many others from Easter Island to Jamestown – are facing an existential threat from climate change.

Perched on the breathtaking Atlantic coast of Mainland, the largest island in Scotland’s Orkney archipelago, are the remains of the Stone Age settlement of Skara Brae, dating back 5,000 years. Just feet from the sea, Skara Brae is one of the best preserved Stone Age villages in the world — a complex of ancient stone house foundations, walls, and sunken corridors carved out of the dunes by the shore of the Bay of Skaill. Fulmars and kittiwakes from the vast seabird colonies on Orkney’s high cliffs wheel above the coastal grassland of this rugged island, 15 miles from the northern coast of the Scottish mainland. On a sunny day, the surrounding bays and inlets take on a sparkling aquamarine hue.

Older than the Egyptian pyramids and Stonehenge, Skara Brae is part of a UNESCO World Heritage site that also includes two iconic circles of standing stones — the Ring of Brodgar and the Stones of Stenness — and Maeshowe, an exquisitely structured chambered tomb famous for its Viking graffiti and the way its Stone Age architects aligned the entrance to catch the sun’s rays at the winter solstice. These sites, situated just a few miles from Skara Brae, are part of an elaborate ceremonial landscape built by Orkney’s earliest farmers.

Skara Brae and the neighboring sites have weathered thousands of years of Orkney’s wild winters and ferocious storms, but they may not outlive the changing climate of our modern era. As seas rise, storms intensify, and wave heights in this part of the world increase, the threat grows to Skara Brae, where land at each end of its protective sea wall — erected in the 1920s — is being eaten away. Today, as a result of climate change, Skara Brae is regarded by Historic Environment Scotland, the government agency responsible for its preservation, as among Scotland’s most vulnerable historic sites.

Like the rest of Scotland, Orkney’s climate is changing faster now than at any time since instrumental measurements began.

A global crisis for cultural heritage is unfolding along our coasts, but it’s one that only a handful of archaeologists, preservationists, and climate scientists are yet paying attention to. In 2014, for example, a study from the Potsdam Institute for Climate Impact Research found 136 World Heritage sites vulnerable to sea level rise, including the Statue of Liberty and the Sydney Opera House. The U.S. National Park Service has identified erosion threats to archaeology at many of its properties, including Historic Jamestown in Virginia. Recent research shows that some of the magnificent moai statues of Easter Island are in danger of collapsing into the sea as a consequence of coastal erosion. The threat is also severe in the Arctic, where protective winter sea ice is disappearing and permafrost is thawing. Storms tear away the shoreline and wash out irreplaceable remains of settlements, hunting camps, and artifacts. Archaeologists are racing to excavate the rapidly disappearing site of Walakpa near Barrow, Alaska, with its evidence spanning 4,000 years of human occupation. Other coastal archaeology is critically endangered at Arctic sites in Canada, Siberia, and Greenland. Resources to investigate and excavate are meager. Because of Orkney’s weathered coast and the sheer density and richness of its ancient remains, many see the archipelago as the world capital of eroding archaeology. Hazel Moore, an archaeologist who has been monitoring erosion impacts in Orkney and the even more northerly Shetland Islands since the early 1990s, says, “In terms of coastal erosion and direct threat, within Orkney and Shetland there are thousands of sites at risk, and probably many we don’t know about that we’re not even recording.”

Remains of the Stone Age settlement of Skara Brae in the Orkney Islands, threatened by sea level rise. ADAM MARKHAM

Moore leads one of Orkney’s several active “rescue digs” in a fast-eroding dune system called the Links of Noltland on the island of Westray, a 90-minute ferry ride from Mainland. Remains of at least 35 stone structures dating from 3300 BC to roughly 1000 BC have been found there so far. In one of those, archaeologists discovered in 2009 the Orkney Venus, Scotland’s earliest known representation of a human. Neolithic settlement sites are rare, and the state of preservation at Noltland is comparable to Skara Brae, although Noltland’s area is considerably larger. Each summer, the excavation team returns not knowing what condition the site will be in after being battered by winter storms.

Like the rest of Scotland, Orkney’s climate is changing faster now than at any time since instrumental measurements began. Average temperatures have risen by about 1.8 degrees F since 1961, and heavy rainfall events and severe storms have become more common. Meanwhile, sea level rise has accelerated during the last 20 years, driving an increase in severe coastal flooding events on Scottish coasts, according to Jim Hansom, a coastal geomorphologist at the University of Glasgow.

Until the 1980s Noltland’s dunes were largely covered in grass, but storms have hammered them, allowing wind erosion to take hold. (Sand quarrying and rabbit damage also have taken a toll.) Intensifying winter winds have scoured away sand and soil so that in some places the dunes have collapsed nearly 20 feet. An ancient midden, or garbage pile, has been exposed to the elements for the first time in thousands of years, with shellfish and snail shells, fish bones, cereal grains, and charred fragments of animal bones discarded by Bronze Age farmers lying directly on the surface. Some of the most exposed portions of the site are no more than 100 yards from the sea and just a few feet above beach level. Moore says that speed of excavation is paramount because “nature is uncovering the site so rapidly.” The evidence for human occupation in Orkney dates back at least 9,000 years, and although we think of the islands as remote today, for several millennia they were a maritime and cultural crossroads, with close links at various times to Ireland, Scandinavia, Greenland, and mainland Europe. In the medieval period, Orkney was only two or three days’ sail by longboat from Norse harbors in Scandinavia. Orkney’s earliest inhabitants had to adapt to climate changes, including post-glacial sea level rise. Seas around Orkney didn’t reach their current level until about 4,000 years ago, perhaps 500 years after Skara Brae was abandoned. It is likely that encroaching sands and increasing salt-spray blown in from the sea eventually made agriculture too difficult so close to the ocean.

Archeologist Julie Gibson on Rousay Island, which has archeological finds dating back more than 5,500 years. ADAM MARKHAM

By roughly 3500 BC, most of Orkney’s forests had been felled, and stone, easily quarried from the islands’ laminated red sandstone deposits, became the building material of choice. Because stone was used, the islands hold an extraordinarily rich repository of archaeological information from the Neolithic period through to the Vikings and beyond. At other archaeological sites in Europe, where wood was used, the organic material has decayed and little is left of buildings, but in Orkney, preservation of ancient structures is remarkable, offering vivid insights into Neolithic life. For example, the houses of Skara Brae contain stone beds, dressers, shelves, and fish storage tanks. “The buildings at Skara Brae indicated a pattern for how people lived,” said Julie Gibson, the Orkney County archaeologist and a lecturer at the University of the Highlands and Islands. “When archaeologists were digging near Stonehenge, they were dealing with houses which had been built in wood, but to the same pattern as in Orkney. They wouldn’t have been able to so rapidly understand how people lived near Stonehenge if they hadn’t been able to draw on the 3-D evidence from Skara Brae.” As at Skara Brae, most of Orkney’s archaeological sites are on or close to the shoreline, just a few feet above sea level. Accelerating sea level rise is already having an impact, according to Gibson. Sixty years ago, local children played inside beautifully preserved Iron Age buildings at Hodgalee on Westray. Since then, seas that have risen five to eight inches have entered and damaged these ancient remains. It’s an “archaeological disaster,” says Gibson, and just a matter of time until all are lost to the water and waves.

The medieval church of St. Mary's Kirk on Rousay Island, another example of Orkney coastal archeology at risk because of climate change. ADAM MARKHAM

The 2013 Intergovernmental Panel on Climate Change report projected a range for global average sea level rise of 1.7 feet to 3.2 feet by 2100, but the latest science suggests that estimate is conservative. The U.K. government has projected a possible rise in sea level of up to 6.2 feet by 2100. On the Orkney Islands, huge waves roll in unimpeded from the deep water of the Atlantic and batter the shore. Most studies show that storm activity in the northern North Atlantic has intensified, and almost all climate change analyses agree that storm intensity will continue to increase. Waves, too, are becoming more damaging. “In the Northeast Atlantic, the significant wave height (the average of the highest third of all waves) has been increasing over the last 40 years at about 0.8 inches per year,” says Hansom. But it’s not the average waves that do the most damage, it’s the biggest ones. Extreme waves up to 56 feet have been recorded off the west coast of Mainland. Storms also appear to be clustering together more often, according to Hansom. “The damage that storms do has a lot to do with the impacts of the previous storm,” he says. “If you have a beach that has been depleted by a storm and then it’s hit by another within a couple of weeks, then the second storm is much more destructive.” The 2017 National Coastal Change Assessment found that Scotland’s coastal erosion rates have doubled since the 1970s. All this could prove disastrous for Orkney’s coastal archaeology.

An international team is rushing to learn as much as it can about a newly discovered Stone Age site before it is swallowed by the sea.

Exemplifying what’s at risk is an extraordinary strip of archaeology on the southwest coast of Rousay Island. Gibson has lived close by since she moved here in the late 1970s to study Viking archaeology. In just a few hundred yards you can hike the entire settled history of Orkney from 3500 BC to the 20th century, including one of the biggest chambered tombs in Scotland, several Iron Age roundhouses (brochs), remnants of a Norse hall, Viking boat ramps, and the ruins of St. Mary’s Kirk, once the heart of medieval Rousay.

Just down the beach from St. Mary’s, an international team is rushing to learn as much as it can about a newly discovered site at Swandro Bay — which includes a chambered tomb that may contain the burials of many Stone Age people — before it is swallowed by the sea. The project also seeks to better understand the mechanisms of erosion on coastal archaeological resources. At Skara Brae too, cutting-edge efforts are underway to record and understand the rate of erosion. A team from Historic Environment Scotland used laser scanners for a detailed 3D digital survey of Skara Brae and its shoreline. Gibson looks at climate impacts both as a threat and an opportunity. She authored the 2008 book, “Rising Tides Revisited: The Loss of Coastal Heritage in Orkney,” in which she suggested that half the known sites in Orkney are at risk from climate change. But she sees a silver lining: “This is an opportunity for people to focus enquiries on eroding archaeology rather than going to look for new sites.”