An 1810-year-old dripstone from the Wanxiang Cave in China provides clues about the development of the Asian monsoon.
Reading aloud Researchers have reconstructed the history of the monsoon from the dripstones of a Chinese cave. They came to a connection with the cultural development of China in the past almost 2, 000 years. For example, the Northern Song Dynasty benefited from heavy monsoon that could be used for rice irrigation. This resulted in higher crop yields, which increased the population. Weak monsoon periods could, however, have contributed to the demise of ruling dynasties such as the Ming Dynasty, speculate the researchers around Pingzhong Zhang from the University of Lanzhou. In the Wanxiang Cave located between Tibet and the loess plateau of northern China, the researchers came upon a stalactite that, thanks to its nature, could be analyzed very precisely. Since the cave is located in a monsoon area, the stalactite that has formed over the millennia reflects changes in the monsoon periods. This allowed the scientists to understand the history of the Asian monsoon.

In their investigations, the researchers found a relationship between the monsoon and the temperature in the northern hemisphere and in China. Thus, it was found that the monsoon was very strong during the medieval warm period from the 9th to the 14th century and rather weak during the subsequent so-called small ice age. The monsoon, which was weak during this period, may have contributed to the decline of the Ming dynasty in the mid-17th century, the researchers explain. During this epoch there were always failures. Famines and peasant uprisings were the result.

However, the relationship between northern hemisphere temperatures and the Asian monsoon has changed since around 1960. Presumably, monsoon has been more affected by greenhouse gases such as carbon dioxide and airborne particles produced by man.

Pingzhong Zhang (Lanzhou University in China) et al .: Science, Vol. 322, p. 940. ddp / science.de? Sonja Römer advertisement

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