July 17, 2023

Beijing – As China initiates a nation-wide cultural heritage survey to log the state of the country’s historical artifacts, researchers say ancient Buddhist murals in Dunhuang and Zhangye, Gansu province, are already under direct threat from unprecedented extreme rainfall linked to climate change, after lasting for centuries in dry, desert conditions.¹ 

Meeting in Beijing today, a group of cultural heritage conservation experts from the Dunhuang Research Academy and climate scientists from Greenpeace East Asia discussed the impact of extreme rainfall in Gansu, the connection to climate change, and what it means for China’s cultural heritage.

“As the climate goes out of whack, deserts see downpour while farmlands get drought. Gansu is famous for its caves and the art stored inside them for centuries. Increased bouts of rainfall in the desert pose an acute risk. Spikes in humidity, flash floods, and cave ins are already happening. And by the time this cultural heritage survey is finished, some artifacts could already be gone,” said Li Zhao, a senior researcher in Greenpeace East Asia’s Beijing office. 

Photos available here and here. 

Since 2000, total rainfall in Gansu province has increased overall while the number of days with rainfall has actually decreased, resulting in a marked increase in bouts of extreme rainfall.² Meanwhile, meteorological records show an average temperature increase of +0.28 degrees Celsius every 10 years between 1961 and 2021 in Gansu. This is faster than the global average. 

Dunhuang’s caves and grottoes are UNESCO World Heritage sites that house paintings, sculptures, and libraries of scrolls stored by a local monastery. The caves date to the 4th century. Zhangye’s cave monasteries are national level heritage site.³ 

Researchers say these sites already show deterioration due to periods of high humidity and rapid fluctuations in humidity during extreme rainfall, as well as the impact of flooding and leaks: 

  • Dunhuang’s cave paintings face high risk when the atmosphere reaches 60-65% humidity, precipitating the crystallization, separation, and build up of salt on the wall painting’s surface, which causes flaking and detachment from the wall. The number 85 cave in the famous Mogao Grotto, for example, already exhibits extensive flaking and detachment.
  • Bouts of extreme rainfall create flash floods and mudslides that have directly impacted the Mogao Grottoes, most severely in 2012. Rainwater also leaks into the cave, which directly impacts cave paintings. Heavy rainfall can also pool in hillsides and cause cave collapses, which have occurred in the area.⁴
  • In Zhangye, the Jinta Temple grotto’s atmospheric humidity reached as high as 93% – when decomposition, rot, and erosion can occur – as well as direct seepage of rainwater during extreme rainfall. Cave paintings and statues exhibited extensive damage from water erosion as well as flaking and detachment.
  • The Jinta Temple grotto and other grottoes in the Mati Temple Grotto cluster in Zhangye, suffer direct damage to their structural integrity from increased rainfall. The Jinta Temple grotto has since August 2022 developed a 0.3-0.5 CM crack on the north-facing side of its central pillar with water seeping through the crack. The ceiling also exhibits chipping on the painting on its ceiling and significant damage to the cave wall. 

“While we’re still working to document, understand, and conserve these pieces of our history, they’re dissolved before our very eyes. This is a painful reality of the impact of climate change. The sites we looked at include some of the most well-funded, best staffed cultural heritage sites in China. And we can see this pernicious impact even in Dunhuang. There are hundreds of less-funded, less-studied sites all around China that are facing these same risks. The best thing we can do is stop climate change. But it’s also urgent that we fund and support conservation efforts here,” Li said.

END

See report briefing (in Chinese) here.

NOTES

[1] China’s National Cultural Heritage Administration began a national cultural heritage survey this year. The process is likely to take three to four years: https://www.gov.cn/xinwen/2023-01/06/content_5735215.htm (link in Mandarin Chinese)

[2] This report uses local meteorological standards to identify extreme rainfall. As such, parts of Eastern Gansu would define extreme rainfall as more than 30mm of rain in one day, while parts of Western Gansu would define extreme rainfall as more than 10 mm of rain in one day. 

[3] Source: http://www.gssn.gov.cn/sngk/jdtj/201811/t20181106_129434.html  (link in Mandarin Chinese)

[4] Source: http://news.sina.com.cn/o/2004-07-30/00233239325s.shtml (link in Mandarin Chinese)

For media enquiries please contact:

August Rick, Greenpeace East Asia, Beijing, ([email protected]), +86 175 1040 4599

Greenpeace International Press Desk, ([email protected]), +31 20 718 2470 (24 hours)