The monsoon rains that have inundated several central and southern provinces this month have brought the most severe flooding that Fujian, Jiangxi, Hunan and Guizhou have suffered in half a century. Official figures put the death toll in June at at least 235 with a further 119 unaccounted for. At least 379 people have died as a result of flooding so far this year, the deadliest toll since 1998 when 3,600 died as a result of the rains.
On Monday, at least 107 people were buried by a rain-triggered landslide in Guizhou. In all more than 29 million people have been affected, with one in 10 those having to be evacuated from their homes. The economic cost is put at upwards of 82 billion yuan ($12 billion). Emergency relief efforts and fortification of riverbanks continues, as does the torrential rain with more in the forecast.
A team of Chinese and American scientists has drawn a link between the demise of the Tang, Yuan and Ming imperial dynasties and the strength of monsoon rains.
An ancient stalagmite found rising from the floor of Wangxiang Cave in Gansu province has allowed the researchers, Zhang Pingzhong, a geologist at Lanzhou University, and his colleagues and Hai Cheng, a geologist at the University of Minnesota, to chart the rise and fall in strength of Asian monsoons for over 1,800 years. The three dynasties all came to their end during weak, and thus dry monsoon periods. The scientists, writing in the journal Science (link here, but it is a subscription site; BBC summary here), speculate that weak monsoons mean that the monsoon rains necessary for growing rice don’t spread far enough west and north, leading to poor harvests and civil unrest. They link the variability in the strength of monsoons to temporary weakening of the sun, which also seems to have contributed to the collapse of Maya civilization in Mesoamerica and the advance of glaciers in the Alps.
How tight the connection between monsoons and political demise will no doubt make for debate among geologists and historians. Nature quotes Zhang Deer, chief scientist of the National Climate Centre in Beijing, saying that climate is just one of the many factors that determine the rise and fall of Chinese dynasties.
More interestingly, the scientists found that in the past half century greenhouse gases and aerosols have taken over from natural variability to become the dominant influence on the monsoon. A compelling reason for China’s leaders to take getting an international agreement on global warming seriously.