From the CO2Science Archive: The authors write that “the middle reach of the Yangtze River possesses abundant depositional resources (e.g. stalagmite, peatland and lake sediments),” which they indicate “are reliable information carriers for paleoclimate and paleoenvironmental reconstruction.” And they add, in this regard, that “the reconstruction of long-term paleoclimate change would provide the premise for accurate prediction of the future,” which is something nearly everyone would like to see.

Paper reviewed: Gu, Y., Wang, H., Huang, X., Peng, H. and Huang, J. 2012. Phytolith records of the climate change since the past 15000 years in the middle reach of the Yangtze River in China. Frontiers of Earth Science 6: 10-17.

What was done
Working with a sediment core extracted at Zhoulao town in China’s Jianli County in AD 2000, Gu et al. reconstructed a high-resolution record of paleoclimate change over the past 15,000 years in the middle reaches of the Yangtze River. This they did via phytolith analysis, after which they compared their results with paleoclimatic indicators derived from stalagmites, peatlands, North Atlantic deep-sea sediments (Bond et al., 1997, 2001), the Loess Plateau of Central China, and Arabic Sea sediments.

What was learned
The five Chinese scientists identified eight climatic phases over the course of their temperature reconstruction: the Last Glacial Maximum (20-14.8 cal ka BP), the Last Deglaciation (14.8-11.9 cal ka BP), a low temperature phase in the Early Holocene (11.9-8 cal ka BP), the Holocene Optimum (8-4.9 cal ka BP), the Holocene Katathermal (4.9-1.1 cal ka BP), the Medieval Warm Period (1.1-0.7 cal ka BP), the Little Ice Age (0.7-0.15 cal ka BP) and Modern Warming (0.15 cal ka BP-present). In addition, they discovered that the climate history of their research area had strong links with the contemporary histories of the Indian Summer Monsoon, the Asian Summer Monsoon, and the Holocene drift-ice events of the North Atlantic Ocean, which were discovered and described by Bond et al. (1997, 2001), who attributed them to solar variability.

What it means
In no uncertain terms, Gu et al. state, in the concluding sentence of their paper, that the good correlation that exists between their climate history of the middle reaches of China’s Yangtze River and the Bond events of the North Atlantic Ocean “reveals that solar activity controls the Earth surface climate system at the centennial and millennial scales.”

References
Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffmann, S., Lotti-Bond, R., Hajdas, I. and Bonani, G. 2001. Persistent solar influence on North Atlantic climate during the Holocene. Science 294: 2130-2136.

Bond, G., Showers, W., Chezebiet, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hajdas, I. and Bonani, G. 1997. A pervasive millennial scale cycle in North-Atlantic Holocene and glacial climates. Science 278: 1257-1266.