Architecture often takes a cue from the climate—the thick-walled buildings characteristic of the American Southwest, for instance, are designed to keep interior spaces cool even in sweltering temperatures. Now, researchers have shown that ancient people adapted their architecture in response to climate change. On the basis of analyses of architectural and meteorological records, scientists propose that roof design in northern China changed over a millennium in response to variations in snowfall.
A Marriage of Architecture and Atmospheric Science
Siyang Li, an archaeologist, and Ke Ding, an atmospheric scientist, both at Nanjing University in China, were inspired to study the link between climate change and architecture as a way of combining their research interests. “We were thinking about what we could do together,” said Ding, who is married to Li.
After considering several aspects of traditional Chinese architecture, Li, Ding, and their collaborators decided to focus on roofs, specifically their slopes. “The slope of a roof is very easy to understand,” said Ding.
The team amassed records of roughly 200 wooden buildings constructed in northern China from the 8th to 18th centuries (from the middle to late Tang dynasty to the middle of the Qing dynasty). That time span was dictated by constraints: It was significantly more difficult to locate measurements from older structures, and newer buildings tend to incorporate stronger materials, ensuring that their design is less influenced by climate-related stresses. “Nowadays, we’re using more bricks and other materials,” said team member Aijun Ding, an atmospheric scientist at Nanjing University.
For each building, the researchers calculated the ratio of its roof’s height to its span. Because that value—the roof’s slope—reflects a building’s ability to shed precipitation, perhaps it might exhibit a correlation with climate change over the intervening millennium, the team surmised.
From Temperature to Snowfall
To infer what the climate was like in northern China from the 8th to 18th centuries, the team mined published paleoclimatic reconstructions. Those data provided estimates of temperature anomalies, which the team then translated into estimates of snowfall by analyzing recent snow records in China. “We investigated the relationship between temperature and snowfall for the past 40 years,” said Aijun Ding. That methodology allowed the team to pinpoint times in the past when snowfall would likely have been extreme and, therefore, more steeply pitched roofs would have been advantageous.
The researchers found that roofs in northern China tended to be steeper, on average, during colder periods. That finding suggests that ancient Chinese architecture was influenced by climatic changes, the team suggests. And snowfall was the likely driver, as opposed to rainfall, the researchers propose. That’s because roof slopes tended to be shallower during warmer periods, precisely when it’s wetter, said Ke Ding. “If the roof [slope] changed according to rainfall, it should be steeper in warmer periods.”
The team highlighted Longmen Temple, a complex in Shanxi Province in northern China, as having multiple buildings exemplifying these climate-induced changes. Three of four of its main buildings with well-known construction dates follow the predicted trend. “It’s consistent with the changes that we see,” said Li.
These findings, published in September in Science Advances, reveal that people centuries ago deliberately altered their architectural practices in response to climate change, said Ke Ding. “People have adapted to climate change for a long time.”
More to Do
That’s heartening, given the rapid climate change the planet is currently experiencing—people in the past made changes, and we’re certainly capable of doing the same today. And we’ve already started: As intense hurricanes become more common, coastal structures are being built to stricter standards, said Nicholas Rajkovich, an architect at the University at Buffalo not involved in the research. “There are newer codes and standards that have been put in place.”
Even so, there’s plenty more to do, said Rajkovich. “The changes that we expect to see here in the next 30, 50, 70 years are really going to be significant. I have grave concerns that many buildings are not ready to withstand those shocks and stresses.”
—Katherine Kornei (@KatherineKornei), Science Writer