On the night of July 29, 2024, a 15-meter tall square monument in Michoacán, Mexico, suddenly collapsed under the pressure of incessant rains. The pyramid was once one of the best-preserved monuments of the Kingdom of Michoacán civilization, underscoring the cultural heritage now at risk due to climate change. The pyramid is located in Ihuatzio, a well-preserved archaeological site that contains another pyramid, a tower or fortress, and some tombs.
According to a statement from the National Institute of Anthropology and History of Mexico (INAH), the damage was attributed to extreme weather events. High temperatures previously recorded in the area and the resulting drought caused cracks that favored water infiltration inside the pre-Hispanic building. "From there, the collapse became almost inevitable," said INAH, according to Scienze Notizie. The staff of INAH stated that at least six of the site's stepped bodies are in poor condition, including the outer wall, the core, and the retaining wall. Officials are now focused on repairing the building's structure in favor of Mexican cultural heritage.
During the peak of summer in the Northern Hemisphere, heavy rains and thunderstorms struck much of Mexico, with annual maximum one-day precipitation indicating the intensity of this heavy rain. This occurred after the worst drought in Mexico in the last 30 years, when the rains became so scarce that several lakes completely dried up. These extreme weather events demonstrate the increasing threats that climate change poses to cultural heritage sites worldwide. Just before the pyramid in Mexico collapsed, the iconic Doubre Arch in Utah also collapsed, probably due to changes in water levels and erosion.
Local communities are deeply affected by these losses. According to Tariakuiri Alvarez, who identifies as a living member of the Purépecha tribe, their ancestors would have interpreted the collapse of the pyramid at Ihuatzio as a bad omen. In a post on Facebook, Alvarez stated that before the arrival of foreign conquerors in Mexico, something similar had happened, and it was because the gods were unhappy.
Across the globe, other archaeological sites face similar threats from climate change. In the Arctic, indigenous artifacts are being destroyed as the permafrost thaws due to rising temperatures, with thaw depth several tens of centimeters deeper in many places than it was 30 years ago. Measurements document that the permafrost is thawing deeper than before, with new records set in 2024, according to NRK Forhold.
Researchers at Svalbard are witnessing the rapid deterioration of archaeological cultural heritage sites. "They are simply rotting faster," said Lise Loktu, an archaeologist and researcher at Svalbard Museum, according to NRK Forhold. Loktu explains that warmer climate is causing textiles to deteriorate faster than before. "It is about the permafrost thawing deeper in the summer. There is also leaching from the sea and the ground is cracking. Then you get an influx of oxygen and water ingress, and that increases the bacterial degradation," she said.
Permafrost on Svalbard has kept graves dating back to the 1600s very well preserved. However, the preservation conditions are changing. Inside the storage room at Svalbard Museum, Loktu and osteologist and forensic anthropologist Elin Brødholt are examining skeletons and textiles. The researchers observe that while the skeletons remain well-preserved, textiles excavated recently are in worse condition than those excavated in the 1980s.
The consequences of climate change extend globally. In Venice, the frequency and intensity of flooding have increased due to climate change, which includes not only rising sea levels but also extreme weather events that endanger precious World Heritage sites. Venice, an iconic heritage city founded in the 5th century, has always been vulnerable to rising sea levels and the threat of flooding.
UNESCO estimates that one in six cultural heritage sites is threatened by climate change, demonstrating the international recognition of the potential risks to cultural heritage. Africa has the most World Heritage sites at risk from climate fluctuations, with 103 UNESCO World Heritage sites, while Europe ranks second with about 21 affected sites.
Archaeologists express concern over the lack of coordination among climate policymakers regarding the impact of climate change on cultural heritage. Funding is the main problem for archaeological preservation in the face of climate change, and there is not enough money to save all archaeological sites threatened by it. "We have to have conversations about loss and what people value," said Dr. Mairi Davies of Historic Environment Scotland, according to Mint.
Sites such as the Knowe of Swandro in the Orkney Islands are turning to laser scanning and other technologies to capture a digital record for future generations. Every summer, a team of archaeologists descends on Rousay to sift through the evidence at the Knowe of Swandro site. However, time is not on their side because rising sea levels and more frequent storms are washing away sediment where the site sits.
The Knowe of Swandro contains the remains of Iron Age and Norse settlements, though it appears at first glance to be a pile of rubble. Coastal erosion has destroyed most of its most important features, including a dwelling from the Iron Age. "The final third will break apart and disappear within the next couple of years," said Stephen Dockrill, who co-leads the excavation, according to Mint.
Similar challenges are faced in other regions. In Iraq, an ancient city is being buried under tonnes of sand, exacerbated by climate change. At Vindolanda in the north of England, the waterlogged soil that preserved Roman tablets for millennia is drying out because of climate change.
Extreme weather events are a natural part of heritage and are unavoidable in the future. According to a study published in Nature, despite uncertainties in simulations of models, a global assessment of the challenges of climate extremes on world heritage sites under future simulations is still necessary. Mitigation efforts and management of human activities are necessary to protect world heritage sites.
In Egypt, the Information and Decision Support Center of the Egyptian Cabinet issued a new analysis on "The Impact of Climate Change on Cultural and Archaeological Heritage." The analysis reviewed the impact of climate change on cultural and archaeological heritage by discussing how climatic phenomena affect archaeological sites. It described how the Egyptian state has dealt with these threats and which archaeological areas have been affected.
The Egyptian government has implemented programs and projects to preserve the sustainability of archaeological sites and protect them from climate change effects. Notable projects include the restoration of the Great Hypostyle Hall at Karnak Temples, the groundwater level reduction project in Kom El-Shoqafa tombs, and the restoration and development project of Dendera Temple.
At the COP 27 Climate Summit in Sharm El Sheikh, the Islamic World Educational, Scientific and Cultural Organization (ICESCO) launched an initiative to create a fund to protect heritage sites and museums from climate change damages. This initiative was in partnership with the Egyptian Ministry of Tourism and Antiquities.
Efforts like these are crucial, but archaeologists warn that more needs to be done. "Which sites should be saved, and which sites should be allowed to decay?" said Dr. Jørgen Hollesen from the National Museum of Denmark, according to Mint.
The global movement to preserve cultural heritage is a reaction to actual losses and damages to heritage sites, as archaeological sites are damaged or disappear, leading to diminished historical knowledge and tourism. Countries with fewer resources will get priority in funding for cultural heritage preservation, according to Lazare Eloundou Assomo, the head of UNESCO's World Heritage Centre.
"It is high time to put a roadmap on the way," said Hessen's Minister of Art and Culture, Timon Gremmels, as reported by Süddeutsche Zeitung. Gremmels emphasized that emergencies that can develop into real disasters must be identified early in order to act accordingly if necessary. He stated, "Images, books, and buildings need to be made climate-resilient."
This article was written in collaboration with generative AI company Alchemiq