Wet phases in tropical southern Africa during the last glacial period

摘要

A 45,000-year high-resolution sedimentary record from Lake Masoko in Tanzania shows the climate in this part of East Africa to have been characterized by a short and less severe dry season during the Last Glacial Maximum. Moisture and lake-level proxies, pollen assemblages and magnetic susceptibility, indicate that rainfall in the Masoko area was strongly controlled by low-latitude insolation (i.e., precessional forcing). Such observations contrast with the climatic patterns previously reconstructed in East Africa for the last glacial. Indeed, widespread dry conditions are generally observed and are attributed to the predominant control of high latitude glacial forcing over insolation forcing on the tropical hydrology. However, during the Younger Dryas cold event, out of phase with regional insolation behaviour, wetter conditions prevailed in this area, suggesting that the rainfall belt over Africa was probably shifted to the South, bringing moisture to the southernmost tropics.