ABSTRACT
Climate model sensitivity experiments are used to assess the sensitivity of African and Asian climate to changes in solar insolation, high-latitude glacial ice cover, North Atlantic sea surface temperatures, and South Asian orography boundary conditions. Model climate responses to these boundary condition changes are discussed in terms of their response magnitude, regional extent, and response season signatures. By region, West African climate was most sensitive to cool North Atlantic SSTs which promoted annually cooler and drier surface conditions and stronger trade winds. East African/Arabian climate experienced annually cooler and drier conditions due to downstream effects of high-latitude ice sheets; the region was very sensitive to South Asian orographic changes as well. South Asian climate was very sensitive to variations in monsoon intensity resulting from orbital insolation variations and changes in Tibetan/Himalayan orography. These model results stress the importance of high-latitude boundary condition changes in affecting low-latitude African and Asian climate. Plio-Pleistocene African paleoclimate can be understood in terms of the relative influences of high- and low-latitude forcing factors.
