Impact of postglacial warming on tropical convection and precipitation patterns in the Indonesian Archipelago

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The primary objectives of this research proposal are (1) to decipher regional precipitation patterns across the Indonesian-Australian archipelago during the last glacial cycle with specific emphasis on transient warming and cooling episodes during Heinrich and Dansgaard-Oeschger Events, the Bølling/Allerød, Younger Dryas and early Holocene northern hemisphere insolation maximum, (2) to elucidate primary controls of tropical rainfall variability during successive climate cooling and warming episodes, and (3) to test the hypothesis that a reduction in tropical convection and weakening of the Walker circulation during tropical warming results in a spatially complex precipitation pattern rather than a uniform rainfall increase over the region. To achieve these objectives we propose to reconstruct the terrigenous runoff from Borneo, Sulawesi, Java and Sundaland into the Makassar Strait, southern Celebes Sea and Flores Sea in well dated sediment archives, positioned to cover large catchment areas from major river deltas. We will integrate XRF-scanner derived high resolution geochemical records with sea surface temperature and salinity estimates, based on Mg/Ca and δ18O measurements of the planktonic foraminifer Globigerinoides ruber. Our reconstruction will provide an essential regional database and a robust framework to test modeling predictions of precipitation change associated with future global climate warming.