Influence of the intertropical convergence zone on the East Asian monsoon

Abstract

The Asian-Australian monsoon is an important component of the Earth's climate system that influences the societal and economic activity of roughly half the world's population. The past strength of the rain-bearing East Asian summer monsoon can be reconstructed with archives such as cave deposits 1, 2, 3 , but the winter monsoon has no such signature in the hydrological cycle and has thus proved difficult to reconstruct. Here we present high-resolution records of the magnetic properties and the titanium content of the sediments of Lake Huguang Maar in coastal southeast China over the past 16,000 years, which we use as proxies for the strength of the winter monsoon winds. We find evidence for stronger winter monsoon winds before the Bølling-Allerød warming, during the Younger Dryas episode and during the middle and late Holocene, when cave stalagmites suggest weaker summer monsoons 1, 2, 3 . We conclude that this anticorrelation is best explained by migrations in the intertropical convergence zone. Similar migrations of the intertropical convergence zone have been observed in Central America for the period ad 700 to 900 (refs 4-6), suggesting global climatic changes at that time. From the coincidence in timing, we suggest that these migrations in the tropical rain belt could have contributed to the declines of both the Tang dynasty in China and the Classic Maya in Central America.

A preliminary analysis of economic fluctuations and climate changes in China from BC 220 to AD 1910

“…This transportation of necessities helped delay the total collapse of the Tang Dynasty's economy by approximately 100 years (Zhao 2002). Our series-based long-term statistical results do not support the idea that prolonged drought led to the fall of the Tang Dynasty (Yancheva et al 2007;Zhang et al 2008), but support the conclusion of Zhang et al (2010a). However, there are some limitations of the precipitation reconstruction used in this paper because it does not cover the whole China like the economic series.…”

“…Quantitative investigations of the economic effects of longterm climatic perturbations are still limited by the dearth of long-term and high-resolution data that indicate the dynamics of socioeconomic processes. Quantitative surveys based on multi-proxy comparisons not only have been pursued by PAGES (2009) but are also essential to help reduce uncertainty and avoid environmental determinism that is related to climate-society research, specifically when considering that some statements are growingly criticized as too simplistic and mono-causal (Butzer and Endfield 2012;Turner 2010;Butzer 2012;Yancheva et al 2007;Zhang and Lu 2007;Zhang et al 2008;Zhang et al 2010b;Cheng et al 2010).…”

Assessing influences on speleothem dead carbon variability over the Holocene: Implications for speleothem-based radiocarbon calibration

“…Consistent with this hypothesis, DCP is remarkably stable in Hulu Cave speleothem H82 throughout the Younger Dryas (YD) climate event, which was likely a period of reduced EASM intensity (Wang et al, 2001;Yancheva et al, 2007). The Bahamas speleothem GB-89-24-1 is also stable over the Younger Dryas interval, though GB-89-25-3, which has a much higher average DCP, shows large fluctuations in DCP at the YD suggesting that climate did have an effect on DCP in some speleothems in the region during the YD interval.…”

Hydroclimatic shifts in northeast Thailand during the last two millennia – the record of Lake Pa Kho

“…Wang et al, 2005). Yet high-resolution tree ring , marine (Anderson et al, 2002;Newton et al, 2006;Oppo et al, 2009), coral (Cobb et al, 2003), speleothem (Sinha et al, 2011a;Zhang et al, 2008), and lake (Yancheva et al, 2007) studies show that substantial decadal to centennial variations in summer monsoon intensity were superimposed on the longterm trend. Various hypotheses have been brought forward through the last millennium Pages 2K, Consortium, 2013).…”