Quantification of southwest China rainfall during the 8.2 ka BP event with response to North Atlantic cooling

Yuhui Liu,Chaoyong Hu

doi:10.5194/cp-12-1583-2016

Abstract

Abstract. The 8.2 ka BP event could provide important information for predicting abrupt climate change in the future. Although published records show that the East Asian monsoon area responded to the 8.2 ka BP event, there is no high-resolution quantitative reconstructed climate record in this area. In this study, a reconstructed 10-year moving average annual rainfall record in southwest China during the 8.2 ka BP event is presented by comparing two high-resolution stalagmite δ18O records from Dongge cave and Heshang cave. This decade-scale rainfall reconstruction is based on a central-scale model and is confirmed by inter-annual monitoring records, which show a significant positive correlation between the regional mean annual rainfall and the drip water annual average δ18O difference from two caves along the same monsoon moisture transport pathway from May 2011 to April 2014. Similar trends between the reconstructed rainfall and the stalagmite Mg ∕ Ca record, another proxy of rainfall, during the 8.2 ka BP period further increase the confidence of the quantification of the rainfall record. The reconstructed record shows that the mean annual rainfall in southwest China during the central 8.2 ka BP event is less than that of present (1950–1990) by ∼ 200 mm and decreased by ∼ 350 mm in ∼ 70 years experiencing an extreme drying period lasting for ∼ 50 years. Comparison of the reconstructed rainfall record in southwest China with Greenland ice core δ18O and δ15N records suggests that the reduced rainfall in southwest China during the 8.2 ka BP period was coupled with Greenland cooling with a possible response rate of 110 ± 30 mm °C−1.

Highlights

As evidence in support of global warming becomes stronger, it is apparent that the anticipated rise in sea levels may be higher than expected (Rahmstorf, 2007) and the frequency and amplitude of abrupt climate change (Martrat et al, 2004; Pall et al, 2007) may be greater
This study further addresses the sensitivity of the climate of southwest China to North Atlantic cooling during the 8.2 ka BP event, providing quantitative data for simulating this global event in climate system models
The average δ18O difference between HS4 and DA is 1.0 ‰ during the whole Holocene (Hu et al, 2008), while the average δ18O value during the 8.2 ka BP event shown in Fig. 3b is much lower at 0.26 ‰

Summary

Introduction

As evidence in support of global warming becomes stronger, it is apparent that the anticipated rise in sea levels may be higher than expected (Rahmstorf, 2007) and the frequency and amplitude of abrupt climate change (Martrat et al, 2004; Pall et al, 2007) may be greater. The highest magnitude variation across the low to high latitudes makes a viable target for numerical modelings (Daley et al, 2011; Morrill et al, 2011) and may offer insight into the sensitivity of climate response in different areas (Condron and Winsor, 2011; LeGrand and Schmidt, 2008) This event was firstly identified in Greenland ice cores (Alley et al, 1997), showing a duration of 160 years (Thomas et al, 2007) with a temperature drop of 3.3 ± 1.1 ◦C in central Greenland (Kobashi et al, 2007) and is known globally (Dixit et al, 2014; Morrill et al, 2013; Ljung et al, 2008; Ellwood and Gose, 2006). As most records associated with this event mainly derived from North Atlantic and Europe (Daley et al, 2011; Szeroczynska and Zawisza, 2011; Snowball et al, 2010; Hede et al, 2010; Domínguez-Villar et al, 2009; Prasad et al, 2009), the question remains as to how much it influenced the East Asian monsoon area (EAMA)

Methods

Results

Conclusion