Holocene stalagmite δ¹⁸O records in the East Asian monsoon region and their correlation with those in the Indian monsoon region

Abstract

We compare well-dated Holocene stalagmite δ18O records from the East Asian Summer Monsoon (EASM) region and from the Indian Summer Monsoon (ISM) region. We found that the pattern of latitudinal change of speleothem δ18O values from the Indian monsoon region to the East Asian monsoon region is almost identical to that of modern precipitation. This suggests that the modern moisture transport route from the Indian Ocean to the East Asian monsoon region has existed since at least the early Holocene. The δ18O records from both regions exhibit a remarkably similar trend of variation in that the values are more negative during the early Holocene, rapidly become heavy from the mid-Holocene, and are heaviest during the late Holocene. The stalagmite δ18O changes in the East Asian monsoon region are statistically well correlated with those in the Indian monsoon region, both over the entire Holocene and in detail over the last 2000 years. However, in contrast to the obvious consistency of the δ18O values in all of the speleothem records, both instrumental and historical climate records indicate significant spatial variations in rainfall over eastern China. The early-Holocene strong EASM pattern referred from speleothem δ18O in the East Asian monsoon region is quite different to that of other paleoclimatic records such as Holocene paleosol development in the Chinese Loess Plateau, eolian activity in the northern Chinese sandlands, and lake sediments in EASM-dominated region in China, in which the strongest EASM was documented during the mid-Holocene. These findings suggest that the speleothem δ18O record from the East Asian monsoon region may not record EASM variability, but rather that it is controlled by variations in the isotopic composition of precipitation, which is determined mainly by rainfall variability in the ISM region.

Linkages between climate, fire and vegetation in southwest China during the last 18.5ka based on a sedimentary record of black carbon and its isotopic composition

“…3h, Dykoski et al, 2005) and Hulu Cave (Fig. 3h, Wang et al, 2001) in the EASM region, which are argued to reveal the precipitation variability of the ISM rather than the EASM variability (Chen et al, 2014a;Yang et al, 2014), have also recorded these events. The overall trend of fire history in southwest China during the last deglaciation generally tracks changes in ISM intensity, or the amount of precipitation.…”

Investigating the long-term palaeoclimatic controls on the δD and δ18O of precipitation during the Holocene in the Indian and East Asian monsoonal regions

“…Yang et al, 2014;Dong et al, 2015;Liu et al, 2015). However, the inconsistent spatial distribution of summer precipitation in the EASM region is also widely known, described colloquially as "flood in the south and drought in the north", or "drought in the south and flood in the north".…”

“…Discussion has focused on the factors that may affect Chinese δ 18 O s values, such as ISM intensity (Pausata et al, 2011;Yang et al, 2014;Liu et al, 2015), different vapor source ratios (Clemens et al, 2010), and a "circulation effect" (Tan, 2009(Tan, , 2011(Tan, , 2014Tan and Nan, 2010;Caley et al, 2014). The Chinese δ 18 O s record may not therefore be an unambiguous indicator of EASM intensity.…”

Variations in the oxygen isotopic composition of precipitation in the Tianshan Mountains region and their significance for the Westerly circulation

“…This implies that the negative and positive shifts in stalagmite δ 18 O are caused by variations in the transport of water vapor from more distal to more proximal sources (Tan, 2011(Tan, , 2014, or that they reflect differences in precipitation patterns and water vapor pathways (Dayem et al, 2010). On an orbital time scale, in monsoonal China stalagmite δ 18 O records spanning the Holocene are considered to be an indicator of the intensity of the Indian Summer Monsoon (ISM) rather than the East Asian Summer Monsoon (EASM) (Yang et al, 2014;Chen et al, 2014). During the last interglacial period, the differences between loess-paleosol profiles and stalagmite records from monsoonal China indicate that stalagmite δ 18 O is not a direct index of EASM evolution (Rao et al, 2014).…”