Indian summer monsoon forcing on the deglacial polar cold reversals

• Published in: Journal of Earth System Science
• Main Authors: Banakar, Virupaxa K, Baidya, Sweta, Piotrowski, Alexander M., Shankar, D
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer India 2017
• Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems; Antarctic; Greenland; Indian; Antarc*
• Online Access: http://eprints.esc.cam.ac.uk/4059/; http://eprints.esc.cam.ac.uk/4059/1/s12040-017-0864-5.pdf; https://doi.org/10.1007/s12040-017-0864-5

The deglacial transition from the last glacial maximum at ∼20 kiloyears before present (ka) to the Holocene (11.7 ka to Present) was interrupted by millennial-scale cold reversals, viz., Antarctic Cold Reversal (∼14.5–12.8 ka) and Greenland Younger Dryas (∼12.8–11.8 ka) which had different timings and extent of cooling in each hemisphere. The cause of this synchronously initiated, but different hemispheric cooling during these cold reversals (Antarctic Cold Reversal ∼3∘C and Younger Dryas ∼10∘C) is elusive because CO2, the fundamental forcing for deglaciation, and Atlantic meridional overturning circulation, the driver of antiphased bipolar climate response, both fail to explain this asymmetry. We use centennial-resolution records of the local surface water δ18O of the Eastern Arabian Sea, which constitutes a proxy for the precipitation associated with the Indian Summer Monsoon, and other tropical precipitation records to deduce the role of tropical forcing in the polar cold reversals. We hypothesize a mechanism for tropical forcing, via the Indian Summer Monsoons, of the polar cold reversals by migration of the Inter-Tropical Convergence Zone and the associated cross-equatorial heat transport.