While wars and revolutions have long threatened cultural heritage — most recently in Iran and Ukraine — a new danger is emerging: climate change.
UNESCO World Heritage sites, from the 4,000-year-old Ziggurat of Ur to the Moai of Easter Island, are suffering increased erosion and deterioration as temperatures rise and storms and droughts intensify. A 2025 study found that 80% of World Heritage sites face climate stress as materials like wood and stone struggle to adapt to a hotter world.
Here are several of the most climate-vulnerable UNESCO-listed cultural sites.
‘Cradle of civilization’: Ziggurat of Ur
Thousands of years of history could vanish as rising temperatures drive extreme erosion across Iraq’s ancient southern cities. The Ziggurat of Ur, a 4,000-year-old pyramid temple to the moon god Nanna, is crumbling as shifting sand dunes and strong winds wear away its northern side.
The site is also affected by rising salty groundwater — linked to prolonged heat and drought — which erodes the mud bricks of Mesopotamian temples and religious sites where Sumerian rituals were practiced. Kazem Hassoun, an inspector at the antiquities department in Dhi Qar (the modern province once at the heart of Sumerian civilization), said salt deposits appearing due to global warming could eventually cause the “complete collapse of the mud bricks” as salt crystals seep into and expand within porous foundations.
Further along the Euphrates, the ancient city of Babylon’s clay-based structures are at risk from high salinity. At the Temple of Ninmakh, a 7th-century B.C.E. monument dedicated to the mother goddess, archaeologists are reviving a 7,000-year-old technique to produce desalinated mudbricks to combat salt erosion.
Mosques of Isfahan, Iran
Beyond the threat of conflict to Persia’s religious monuments, Isfahan’s historic mosques are increasingly vulnerable to climate change. The Masjed-e Jame, or Friday Mosque, embodies 12 centuries of mosque architecture. Started in 841 C.E. and repeatedly rebuilt and renovated, it is considered a “museum of Iranian architecture” and a blueprint for religious and educational buildings across the region.
Nearby, the Meidan Emam World Heritage Site — a vast 17th-century square that includes the Imam Mosque with its famed blue-tiled dome — is suffering severe climate impacts. Over-extraction of groundwater, worsened by prolonged droughts, is causing land subsidence. Extreme temperatures and rapidly fluctuating humidity also stress the buildings.
Gradual subsidence forms earth fissures that place major stress on monuments like the Imam Mosque and the Masjed-e Jame. The UNESCO Land Subsidence International Initiative notes that earth fissures in Isfahan Province can be decimeters (10 centimeters) wide and, combined with differential subsidence rates, can “tear buildings apart.”
Easter Island’s ancient Moai statues
The Moai statues on Rapa Nui (Easter Island) could be regularly underwater within half a century, according to a 2025 study by researchers at the University of Hawaii. Ahu Tongariki, the iconic ceremonial platform hosting 15 statues dating back about 800 years, is a UNESCO World Heritage Site that could be battered by large seasonal waves driven by sea-level rise. Coastal flooding could threaten 51 cultural assets in the area.
Noah Paoa, lead author of the study, warned the threat is critical to the living culture and livelihood of Rapa Nui. For the community, these sites are essential for reaffirming identity and revitalizing traditions and are central to the island’s tourism industry. Failure to address the threat could ultimately endanger the island’s UNESCO World Heritage status.
Great Wall of China
Stretching more than 21,000 kilometers (13,000 miles) across northwestern China, the Great Wall is an ancient defensive network built and rebuilt over two millennia and designated a World Heritage Site in 1987. Despite its longevity, the wall is eroding at an accelerating rate, a process researchers link to climate change.
Sections built with rammed earth are particularly vulnerable to extreme wind erosion, heavy rainfall, and salinization, which lead to cracking, disintegration, and potential collapse. Researchers estimate only about 6% of the wall’s total length is well-preserved, while roughly 52% has already disappeared or is highly degraded. They call for urgent conservation measures, including enhancing a mossy protective layer known as a “biocrust.”
Edited by: Teresa O’Connell