Last Glacial Maximum in South America: Paleoclimate proxies and model results

Abstract

Observations in South America based on paleoenvironmental. data for the Last Glacial Maximum (LGM) that shows a generally lower temperatures and reduced precipitation of the region are compared to simulation results from the paleoclimate version of the National Center for Atmospheric Research coupled climate system model. Analyses of the LGM wind simulation for the tropical Atlantic show that the convergence zone does not extend all the way into South American continent during the Austral summer. This would have prevented moisture inflow into the adjacent continental area of equatorial northeastern Brazil. Interpretations of paleoclimate proxy records from this region are consistent with this scenario. In the subtropics, LGM westerlies were weaker and data show characteristics of more humid conditions. At higher latitudes model simulations suggest intensification of the westerlies which, in combination with colder sea surface temperatures would imply less moisture influx into the South American continent from the Atlantic sector. Low lake levels in high southern latitudes and general aridity would support the model findings. Copyright 2005 by the American Geophysical Union.