Paleo-environmental change in Amazonian and African rainforest during the LGM

Abstract

Abstract The paper provides new and comparative insight into the ecological history of the two largest continental tropical forest areas during the Last Glacial Maximum (LGM). The tropical forest regions are of particular interest because they present a large source of heat and have been shown to have significant impact on the extra tropical atmospheric circulation. They are also the most intense land-based convective centers. Thus, especially from the tropics paleoecological information is needed as benchmarks for climate modeling. The African data for LGM climates were published earlier including the reconstructed paleoprecipitation patterns deduced from SSTs. The tropical South American LGM data were interpreted from pollen, geochemical, and δ18O (stable oxygen isotope) data from Brazil and selected surrounding areas. The available terrestrial data are consistent with the SST derived precipitation data for the tropical forests in Brazil and for Africa. However, the impact of LGM climate extremes was less severe in the Amazon than in the Congo basin. The LGM humid forest area (including evergreen and semi-deciduous forest types) in Africa was probably reduced by 84%. In contrast, the Amazon humid forest area probably shrank to 54% of their present-day extension. Still, there are different interpretations with respect to the amount of reduction of the Amazon forest area during the LGM. Although direct information about LGM climates in Amazonia is still limited the more detailed map obtained in the present work, however, allows a more reliable characterization of the last glacial tropical environment than previously published for the Amazon region.