COMBINED INFLUENCE OF AUSTRAL SUMMER INSOLATION AND MILLENNIAL-SCALE ABRUPT EVENTS ON THE SOUTH AMERICAN MONSOON SYSTEM

The South American Monsoon System (SAMS) and the Inter-Tropical Convergence Zone (ITCZ) are the two most important circulation systems affecting climate over tropical South America (SA). Both of these convective systems are closely related to one another, and are sensitive to changes in summer insolation and Northern Hemisphere (NH) boundary conditions. While an increasing number of paleoclimatic archives related to SAMS precipitation have recently been published, most of these paleoclimate reconstructions are located along the eastern slope of the tropical Andes or in southeastern SA. In central SA, most proxy records consist of pollen-based vegetation reconstructions, but these show significant disagreements with the precipitation records to the east and west. Here we present a new high-resolution oxygen isotope record (JAR) of the SAMS, extending back to 33.000 BP from speleothems collected in the southern Pantanal, central SA. Our record shows a competing influence of austral summer insolation with millennial-scale abrupt events during the transition from the Last Glacial Maximum (LGM) to the Holocene and helps explain the divergent results obtained from some paleoclimate records.