Climate change is burying archaeological sites under tons of sand
The Nizari Garrison at Gird Castle withstood the Mongol horde of Hulagu Khan for 17 years before surrendering in December 1270. The fortress rose 300 meters above the surrounding plains of present-day eastern Iran, with three rings of fortifications surrounding its base. But dwindling supplies and an outbreak of cholera forced the defenders to abandon their posts after one of the longest sieges in medieval history.
Eight hundred years later, the remaining fortifications of Gird Castle face an onslaught from a new invader: sand. Over the past three months, Bijan Rouhani, an archaeologist at the University of Oxford, has been monitoring about 700 sites in Iran’s Sistan region using satellite imagery. His comparison between US intelligence photos taken in 1977 and the most recent Google Earth images of the area shows the advance of vast dunes that nearly bury Gird’s fortress.
This summer’s drought has revealed a number of previously hidden archaeological sites, as low water levels allowed archaeologists access to historic ruins in Spain, Iraq and China. But just as climate change gives, it takes away: rising heat is damaging some ancient sites and spurring desertification that is burying others, including Gird Castle. It’s a growing problem with few proven solutions.
“We can see many other sites from the Bronze Age to Islamic periods in the area, as well as ancient rivers and canals,” Rouhani says. “Most of these sites are now buried under sand and affected by the 120-day sandstorm every year.”
The ancient city of Zahedan Kohneh suffered the same fate as Gird Castle. It was the capital of Sistan when Gird fell to the Mongols and was once one of the largest cities in Iran. Today she is draped in a garment of growing sand. Archaeologists surveying sites in other regions, countries, and continents report similar stories. Ahmed Mutasim Abdalla Mahmoud, a sand movement researcher at the University of Nottingham, says sand poses the biggest threat to Sudan’s Nubian pyramids, built around 4,500 years ago. He warns that the 200 pyramids of El Kurru, Jebel Barkal and Meroe on the Nile could soon disappear under the sand.
“The threat has been exacerbated by climate change, which has made the land more arid and sandstorms more frequent,” he wrote on the Conversation. “Quicksand can engulf entire homes in rural Sudan and blanket fields, irrigation canals and riverbanks.”
Mahmoud and other archaeologists agree that people in these areas struggled with encroaching sand dunes for millennia. But climatologists leave no doubt that human activity is accelerating the rate of desertification. Some predict that at the current rate, emissions will cause the Middle East and North Africa region to warm by 4 degrees Celsius over the next 30 years. These rising temperatures cause drought, and drought turns the land into a desert. More than two-thirds of Iran’s land mass now shows “high” or “very high” susceptibility to desertification.