UNESCO World Heritage sites facing the heat

While wars and revolutions have long threatened national cultural heritage sites — most recently in Iran and Ukraine — a new danger has emerged in the form of climate change.

UNESCO World Heritage sites from the 4,000 year-old pyramid temples in Iraq to the ancient statues of Easter Island are facing extreme erosion and deterioration as temperatures rise and storms and droughts intensify. A 2025 study showed that 80% of World Heritage sites are facing climate stress as materials such as wood and stone struggle to adapt to a hotter world.

Here are a few of the world’s 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 World Heritage-listed ancient southern cities due to climate change.

The legendary Ziggurat of Ur, a 4,000-year old pyramid temple built in homage to the moon god Nanna, is crumbling as shifting sand dunes and extreme winds wear away at its northern side. 

The site is also affected by rising salty groundwater — linked to persistent heat and drought — eroding the mud bricks marking the ancient Mesopotamian temples and religious sites where Sumerian rituals were practiced. 

“These salt deposits appeared due to global warming and climate change,” said Kazem Hassoun, an inspector at the antiquities department in Dhi Qar — the modern-day province that was once the heartland of ancient Sumerian civilization. 

Referring to the ancient Royal Cemetery of Ur, Hassoun said the salt deposits could eventually cause the “complete collapse of the mud bricks” at the site since salt crystals seep into the foundations and expand within the porous materials. 

Further along the Euphrates River, the UNESCO World Heritage archaeological sites of the ancient city of Babylon are also at risk of erosion due to high salinity levels — which is endangering ancient clay-based structures.

At the Temple of Ninmakh, a 7th-century B.C.E monument dedicated to the mother goddess of fertility and creation, archaeologists are using a 7,000-year-old technique to create desalinated mudbricks to combat salt erosion. 

Mosques of Isfahan, Iran

While war is the most recent threat to Persia’s grand religious monuments, the mosques built across the millennia in the Iranian city of Isfahan are increasingly vulnerable to a fast-changing climate.

The Masjed-e Jame, also known as the ‘Friday Mosque’, embodies the evolution of mosque architecture over 12 centuries. Started in 841 C.E. and continually constructed, reconstructed and renovated, it is considered a “museum of Iranian architecture,” according to UNESCO, and was a blueprint for religious and educational architecture across Iran, Iraq and Syria.

Nearby, the Meidan Emam World Heritage Site is a vast 17th century central square and home to the Mecca-facing Imam Mosque that is famed for its blue-tiled dome and intricate calligraphy.

But the Imam Mosque forms part of the UNESCO-listed complex that is already suffering severe climate change impacts, including sinking land (subsidence) caused by the over-exploitation of groundwater —made worse by prolonged droughts. Extreme temperatures and sharply fluctuating humidity are also affecting the buildings, say experts. 

Gradual subsidence is causing major stress to ancient monuments like the Imam Mosque and the Masjed-e Jame as earth fissures form where the land is sinking.

“Earth fissures in Isfahan Province can be decimeters [10 centimenters] wide, and together with differential subsidence rates, have the capacity to tear buildings apart,” noted the UNESCO Land Subsidence International Initiative. 

“The cracks are getting deeper, and some columns have tilted,” Bahram Nadi, a member of the specialized land subsidence task force in Isfahan, told the Tehran Times of the Imam Mosque in September 2024. “If urgent action is not taken, we risk losing this invaluable piece of our heritage.” 

Easter Island’s ancient Moai statues 

The world-renowned Moai statues on Rapa Nui, or Easter Island, could be regularly underwater within half a century, according to a 2025 study by researchers from the University of Hawaii. 

Ahu Tongariki, the iconic ceremonial platform in Rapa Nui National Park that hosts 15 statues dating back around 800 years, is a UNESCO World Heritage Site.

Yet this place of deep cultural and historical significance could be battered by large seasonal waves driven by sea level rise linked to climate change, the study said. Coastal flooding could threaten 51 cultural assets in the area.

“This research reveals a critical threat to the living culture and livelihood of Rapa Nui,” said Noah Paoa, a University of Hawaii researcher and lead author of the study, in a statement. 

“For the community, these sites are an essential part of reaffirming identity and support the revitalization of traditions,” he added, noting that they are “the backbone” of the island’s vital tourism industry.

“Failure to address this threat could ultimately endanger the island’s UNESCO World Heritage Site status,” Paoa said. 

Great Wall of China

Extending more than 21,000 kilometers (13,000 miles) across northwestern China, the Great Wall of China is an ancient defensive network of fortifications built and rebuilt over two millennia. The landmark was designated a World Heritage Site in 1987, with UNESCO pointing out that its “historic and strategic importance is matched only by its architectural significance.”

But despite its longevity, the wall is eroding at an accelerating rate, worsened by climate change, according to a team of China-based researchers. 

Because sections were built in many locations with rammed earth, large portions of the edifice are at risk of “severe deterioration” due to extreme wind erosion, heavy rainfall and salinization, leading to “cracking, disintegration, and even eventual collapse,” said the study.

The researchers estimate that only around 6% of the wall’s total length is well-preserved, while roughly 52% has already diappeared or is highly degraded. They are calling for urgent conservation measures, including the enhancement of a mossy protective layer known as a “biocrust.”

Edited by: Teresa O’Connell