Climate Change Tests China’s Ancient Grotto Protection
Since the start of the 2026 flood season, persistent heavy rainfall across northwest China has forced the temporary closure of some of the country’s most treasured cultural heritage sites. The Mogao Caves in Dunhuang, a UNESCO World Heritage site renowned for its 1,600-year-old Buddhist murals, were closed on multiple occasions, while the Maijishan Grottoes and Bingling Temple Grottoes also suspended operations as extreme weather events test the resilience of China’s ancient grotto temples.
The closures highlight a growing challenge: climate change is fundamentally altering the conditions under which these irreplaceable treasures must be preserved. As Xinhua News reported, water has become what researchers describe as the “most deadly disease” for grotto temples, combining direct destructive forces with long-term hidden damage.
The Water Threat: A ‘Visible Spear’ and ‘Hidden Arrow’
China is home to nearly 6,000 grotto temple sites, the most of any country in the world. The “Four Great Grottoes” — the Mogao Caves, Yungang Grottoes, Longmen Grottoes, and Maijishan Grottoes — represent the pinnacle of this heritage. Most of these sites are exposed to outdoor conditions and are highly sensitive to climate and environmental changes.
According to the People’s Daily, the impact of water on grotto temples is twofold. Floods and torrential rain directly damage cave structures, cliff faces, and associated facilities, while persistent rainfall softens and dissolves the materials of grotto artworks, causing surface material loss. Prolonged waterlogging erodes stone carvings and murals, accelerating deterioration.
But as researchers at the Dunhuang Academy put it: “If the impact of floods is a ‘visible spear,’ then the slow erosion of water is a ‘hidden arrow.’” Rainwater seeping into cliff faces softens rock structures and reduces their strength, triggering loosening, detachment, and collapse risks. Rising groundwater levels during flood season carry soluble salts through capillary action into cave walls, where crystallization and expansion cause persistent salt efflorescence and surface weathering. Frequent wet-dry cycles and dramatic temperature fluctuations accelerate material aging, while damp cave environments breed moss and lichen that cause irreversible damage.
Mogao Caves: Engineering Against the Elements
At the Mogao Caves, the Daquan River has historically been both a life source and a threat. The flood control project on the river’s west bank can now withstand a 300-year flood event, a standard upgraded from no rating to 100-year protection in 2003, and then to 300-year protection in 2016 following devastating floods in 2011 and 2012 that damaged the site’s embankments and flooded lower caves, as documented by Workers’ Daily.
Before each flood season, staff conduct systematic inspections and dredging of the river channel to ensure unobstructed flood flow. Annual comprehensive “health checks” cover caves, eaves, rain shelters, temples, archways, pagodas, and cliff faces, including mural and sculpture restoration, facility maintenance, and cliff disease treatment.
A critical scientific breakthrough has established that when cave relative humidity exceeds 67 percent, ground layer salt efflorescence and pigment detachment are triggered. This threshold, identified through extensive research by conservator Fan Zaixuan and his team at the Dunhuang Academy, has become a key operational parameter. As Guangming Daily reported, Fan’s team spent years studying how mixed soluble salts in murals deliquesce and crystallize with humidity fluctuations, and developed desalination materials that can absorb harmful salts from murals.
On June 24, 2026, the Mogao Caves were closed when extreme rainfall pushed humidity near the critical threshold. The site was again suspended on July 29 due to standing water, slippery walkways, elevated cave humidity, and falling rocks, according to the Dunhuang Academy’s official announcement. It reopened the following day after the rain subsided, as confirmed by the academy’s reopening notice.
Regional Sites Adopt Tailored Strategies
The Maijishan Grottoes in Gansu Province have focused on microbial disease prevention and mountain safety control. Before this year’s flood season, staff cleaned microbial hazards in several key caves, and so far these caves have shown no signs of microbial regrowth. The site was temporarily closed twice in July 2026 due to rockfall risks from extreme precipitation.
The Bingling Temple Grottoes, located adjacent to the Liujiaxia Reservoir in a backwater fluctuation zone, face a different challenge. Staff have excavated flood drainage channels and cleared silt accumulation, while cliff reinforcement and rockfall prevention work is underway. The feet of the 171st niche Tang Dynasty seated Maitreya Buddha are being covered to prevent rain erosion. The site’s vulnerability was demonstrated in 2018 when four flash flood and mudslide disasters damaged six lower caves, 50 cliff relief statues, and 10 pagodas, as documented by Silk Roads.
The North Grotto Temple in Qingyang, with its weakly cemented rock, has suffered from long-term rain erosion causing cliff seepage, damp caves, and frequent salt efflorescence. Temporary rain shelters were installed for the south section in 2021 and the north section in 2022, following a year of record rainfall that highlighted the site’s vulnerability, as China Youth Daily reported. Before the 2026 flood season, staff conducted comprehensive risk inspections and reinforced shelter facilities.
A Systemic Shift in Protection Strategy
Grotto flood prevention has shifted from post-disaster repair and passive response to systematic, scientific, and normalized management. Cultural relic departments have established cross-departmental coordination mechanisms and intelligent monitoring and early warning systems that track meteorological conditions, river levels, cave temperature and humidity, and cliff stability in real time.
This evolution reflects a broader transformation in China’s approach to heritage protection. As Li Li, deputy director of the China Academy of Cultural Heritage, noted at the 2025 International Forum on Grotto Temple Protection, “China’s grotto temple protection has entered a new stage: scientific research runs through the entire process, combining rescue protection with preventive protection, shifting from protecting the safety of cultural relic bodies to comprehensive protection of both the body and the cultural relic environment.” The forum, covered by Guangming Daily, highlighted how multi-disciplinary collaboration is driving innovation in grotto conservation.
Institutional reform has also strengthened protection capacity. In 2017, Gansu Province integrated the Maijishan Grottoes Art Research Institute, Bingling Temple Cultural Relic Protection Research Institute, and North Grotto Temple Cultural Relic Protection Research Institute into the Dunhuang Academy. Research projects at Maijishan have since doubled from 10 (2000-2017) to 20 (2017-present), as detailed in a Beijing Daily report on the Four Great Grottoes.
International Cooperation and the Road Ahead
Climate change has also driven international collaboration. At the first International Forum on Grotto Temple Protection held in Dazu, Chongqing in August 2023, experts from 11 countries released the “Dazu Declaration on Grotto Temple Protection under Climate Change,” calling for active protection actions, strengthened scientific research, enhanced monitoring and early warning systems, and better integration of grotto protection with economic and social development, as documented by the Chinese Academy of Social Sciences.
The Dunhuang Academy has been at the forefront of this effort. In June 2025, it co-hosted a seminar on “Meteorological Empowerment for Cultural Relic Protection” with the Gansu Provincial Meteorological Bureau and Cultural Relic Bureau, focusing on climate-heritage relationships and protection strategies, according to the academy’s website. The academy also hosted the 2024 International Forum on Grotto Temple Protection in Dunhuang, where experts from 16 countries discussed protection concepts and technologies, as reported by the academy.
The broader challenge extends beyond grottoes. As a People’s Daily analysis noted, climate change has significantly affected cultural relic protection across China, with water environment changes threatening wooden structures, earthen sites, and grottoes alike. The People’s Daily’s editorial introduction to its special flood season coverage emphasized that extreme weather events are becoming more frequent and intense, posing severe challenges to cultural heritage nationwide.
As China’s grotto protection enters this new era of climate-adaptive management, the experience of the 2026 flood season offers both lessons and hope. The combination of scientific research, preventive measures, institutional coordination, and international cooperation is building a comprehensive protection framework — one that aims to ensure these thousand-year-old treasures endure for generations to come.