Reconstruction of the variability of the southwest monsoon during the past 3 ka, from the continental margin of the southeastern Arabian Sea

Abstract

From temporal variation in delta sup(18) O in Globigerinoides ruber and G. sacculifer and geochemical indices of weathering/erosion (chemical index of alteration, Al and Ti), we infer rapid southwest monsoon (SWM) deterioration with dwindling fluvial and detrital fluxes at ca. 450-650, 1000 and 1800-2200 cal. a BP during the late Holocene. We have evaluated the role of solar influx (reconstructed) and high-latitude climate variability (archived in GRIP and GISP-2 cores) on SWM precipitation. Broadly, our delta sup(18) O climate reconstruction is concordant with GRIP and GISP-2, and supports a teleconnection through atmospheric connection between the SWM and the North Atlantic climate - albeit temporal extents of the Little Ice Age and Medieval Warm Period from high latitude are not entirely coeval. Moreover, there is a humid climate and enhanced precipitation during the terminal stages of the Little Ice Age. The medieval warming (ca. AD 800-1300) is not synchronous either, and is punctuated by an arid event centred at 1000 a BP. Although the delineation of the specific influence of solar influx on SWM precipitation is elusive, we surmise that SWM precipitation is a complex phenomenon and local orography along southwestern India may have a role on the entrapment of moisture from the southwest trade winds, when these hit land