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Abstract Submission No. | ABS-2022-10-0005 |
Title of Abstract | Signals of Holocene climate transition amplified by anthropogenic land-use changes in the westerly-Indian monsoon realm |
Authors | Nicole Burdanowitz*, Birgit Gaye, Kay-Christian Emeis, Tim Rixen |
Organisation | University of Hamburg |
Address | Bundesstraÿe 55 Hamburg, Hamburg, Germany Pincode: 20146 Mobile: 4917648325487 E-mail: nicole.burdanowitz@uni-hamburg.de |
Country | Germany |
Presentation | Oral |
Abstract | In the past the intensity and position of the Indian Summer Monsoon (ISM) have shifted in response to orbitally forced thermal land-ocean contrasts. At the northwestern monsoon margins, interactions between the subtropical westerly jet (STWJ) and the ISM constitute a tipping element in the Earth's climate system because their non-linear interaction may be a first-order influence on rainfall. We reconstructed sea surface temperature (SST), supply of terrestrial material and vegetation changes from a sediment core from the northern Arabian Sea to reconstruct the STWJ-ISM interaction. The Holocene record shows a distinct, but gradual, southward displacement of the ISM in the Early to Mid-Holocene, increasingly punctuated by phases of intensified STWJ events that are coeval with interruptions of North Atlantic overturning circulation (Bond events). The effects of the non-linear interactions culminate between 4.6 and 3kaBP, marking a climatic transition period during which the ISM shifted southwards and the influence of STWJ became prominent. The lithogenic matter input shows an up to 4-fold increase after this time period, probably related to the strengthened influence of agricultural activities of the Indus civilization, with enhanced erosion of soils. This anthropogenic land-use change amplifying the impact of Bond events and adding to the marine sedimentation rates. |