Speleothem records of monsoon interannual-interdecadal variability through the Holocene. (13th December 2021)

• Record Type: Journal Article
• Authors: Parker, Sarah E; Harrison, Sandy P; Braconnot, Pascale
• Is Part Of: Environmental research communications. Volume 3:Number 12(2021)
• Publication Date: 2021-12-13
• Subjects: monsoon -- palaeoclimate -- speleothems -- climate variability -- interannual variability -- Holocene; Environmental sciences -- Periodicals; 333.705
• DOI: 10.1088/2515-7620/ac3eaa
• Languages: English
• ISSNs: 2515-7620

Abstract

Abstract: Modern observations show considerable interannual to interdecadal variability in monsoon precipitation. However, there are few reconstructions of variability at this timescale through the Holocene, and there is therefore less understanding of how changes in external forcing might have affected monsoon variability in the past. Here, we reconstruct the evolution of the amplitude of interannual to interdecadal variability (IADV) in the East Asian, Indian and South American monsoon regions through the Holocene using a global network of high-resolution speleothem oxygen isotope ( δ 18 O) records. We reconstruct changes in IADV for individual speleothem records using the standard deviation of δ 18 O values in sliding time windows after correcting for the influence of confounding factors such as variable sampling resolution, growth rates and mean climate. We then create composites of IADV changes for each monsoon region. We show that there is an overall increase in δ 18 O IADV in the Indian monsoon region through the Holocene, with an abrupt change to present-day variability at ∼2 ka. In the East Asian monsoon, there is an overall decrease in δ 18 O IADV through the Holocene, with an abrupt shift also seen at ∼2 ka. The South American monsoon is characterised by large multi-centennial shifts in δ 18 O IADV through the early and mid-Holocene, although there is no overall change in variability across the Holocene. Our regional IADV reconstructions are broadly reproduced by transient climate-model simulations of the last 6 000 years. These analyses indicate that there is no straightforward link between IADV and changes in mean precipitation, or between IADV and orbital forcing, at a regional scale.