Late Pleistocene tropical aridity synchronous in both hemispheres?

Abstract

THERE is now firm evidence of late Pleistocene aridity in many parts of the tropics in contrast to the belief that high latitude glacial periods were coeval with low latitude pluvial periods¹. A good case may be made for synchronous glacial conditions in both hemispheres during the late Pleistocene^2,3, although there are notable and intriguing exceptions⁴. The latter may result from precipitation variations caused by changes in the incidence of local rain-bearing winds, which in turn result from changes in sea level, ocean currents, and, perhaps, from rainshadow effects. It is reasonable to hypothesise that major climatic changes in extraglacial areas, in particular the non-mountainous parts of the tropics, may also have been synchronous during the late Pleistocene. We propose that the increasing evidence from Africa, India, South America and Australia provides further support for the view that there was widespread tropical aridity in both hemispheres during the late Pleistocene. We will review evidence from the Northern Hemisphere first.