Men try to cool off on a summer day in Beijing. These days, temperatures in… (Associated Press )
Reporting from Beijing — In the debate over global warming, some historical meteorologists in China pose a contrarian view.
Their theory, in a nutshell? Some like it hot.
Looking back over the millenniums, these scientists suggest that China has prospered during periods when temperatures are higher than usual. Conversely, they point out, cold spells have accompanied tragedies along the order of barbarian invasions, collapsing dynasties and civil war.
The proposition that global warming might actually be good for China, or at least a mixed blessing, has been quietly discussed -- and largely dismissed -- in academic circles here.
Those who see possible good in global warming for China rarely speak about it publicly, fearing that they will be seen as being out of step with the scientific mainstream.
But beneath the surface, the theory is not completely discounted.
"There are many different opinions in China about global warming, but people express them only in private," said Ge Jianxiong, director of the institute of Chinese history and geographic studies at Shanghai's Fudan University.
Scientific studies show that the Mongol invasions under Genghis Khan at the beginning of the 13th century were hastened by a sharp drop in temperatures and the phenomenon known as desertification.
"With the cold temperatures there was a drought in Mongolia. Since people were eating livestock which fed on the grasslands, they needed to go south," said Xie Zhenghui, of the Chinese Academy of Sciences' International Center for Climate and Environmental Sciences. "When there was warmer weather and more rain, the Mongols didn't need to attack the south."
The same went for pre-Khan invaders. The Western Zhou dynasty came to an abrupt end in 771 BC, when the effects of cold weather drove barbarian tribes southward to sack the city of Xian, the capital whose glory is epitomized in the artistry of the terra-cotta warriors.
Higher temperatures, on the other hand, have marked periods of major progress.
During the Shang dynasty, (1766-1050 BC), when China began developing its writing system, the average temperature around the Yellow River basin where China was centered was about 52 degrees, slightly higher than today's average.
The golden age of Chinese classics, epitomized by the life of Confucius (551-479 BC) and the Tang dynasty (AD 618-907), which many historians consider the high point of Chinese power and civilization, also coincided with warmer than average weather.
Temperatures also have been rising since Mao Tse-tung's founding of the People's Republic of China in 1949, most sharply in the 1980s and '90s -- the same period the Chinese economy exploded.
"Historically, when the temperatures were warmer, the dynasties were more prosperous," said Xie, of the Chinese Academy of Sciences. "That led some people to theorize that global warming might be good for China."
Xie hastened to add that the theory has been largely dismissed in academic circles -- in large part because it focused on northern dynasties, when in fact the center of power has been shifting southward.
"Warming might be good for agriculture in the north and west, but it would be a disaster for the coastal cities and for the south where Chinese industry is located," Xie said.
These days, temperatures in China are about 1.8 degrees higher than they were in the 1950s and almost as high as in the glory days of the Tang dynasty, according to the Yellow River Conservancy Commission.
Though there are silver linings -- such as a longer growing season for winter wheat in the northwest -- mainstream Chinese scientists worry about the effects of melting glaciers on the Tibetan plateau and flooding in cities like Shanghai. More than 300 miles of the railroad line to Tibet, completed in 2006, was built on permafrost that some say could become unstable if temperatures rise.
"It is true that Chinese civilization peaked during periods of warm weather, but I don't think now that global warming will help either Chinese agriculture or development," said Wang Zheng of the Chinese Academy of Sciences' Institute of Policy and Management.
He said he once believed that climate change could be beneficial for China, but has since changed his mind, and said he isn't alone.
"Five years ago many people believed global warming would be good for China, but in recent years, those voices have disappeared in the mainstream."
Fudan University's Ge, who calls himself a dissenter on the subject of climate change, doesn't believe that rising temperatures will necessarily help China, but he doesn't think they'll hurt much either. He said that China has quietly planned, for example, by installing cooling mechanisms on the railway to Tibet to prevent thawing and accounting for rising sea levels in building near the coast.
"I'm not saying that we shouldn't do everything we can to protect the environment, but these dire predictions of catastrophes are laughable," Ge said.
At the extreme end, some Chinese believe that climate change will hasten the coming of an era in which China dominates at the expense of Europe, where temperatures could drop as a result of a weakening of warming Atlantic ocean currents caused by melting glaciers.
"Europe will become as cold as Siberia. Much arable land will disappear and the continent will no longer be fit for human habitation," a Chinese blogger who writes under the name Feitie Zhiyi suggested in a posting last week. "China should emit more CO2 and make the world warmer! This will only do good to China and bring nothing bad.
"As for the Europeans, it's better to freeze all of them to death!"
Tommy Yang of The Times' Beijing Bureau contributed to this report.