Terrestrial evidence for a spatial structure of tropical-polar interconnections during the Younger Dryas episode

Abstract

The Younger Dryas chronozone, recognised in northern high-latitude areas as a cold event between 11 000 and 10 000 14C yr BP (12 900-11 600 cal. yr BP), seems to manifest itself globally in different ways. Here, we examine well-dated stratigraphic sequences together with high-resolution proxy data plots from sites across our study area, the arid-semi-arid transition zone in northern China. This climatically sensitive area of China records a cold, dry Younger Dryas climate which was punctuated by a brief period of summer monsoon precipitation. We have since found that similar climatic sequences have been reported from the Sahel and the equatorial region of Africa. Based on evidence from these sites, together with other published data, we postulate that precipitation during the Younger Dryas chronozone was indicative of a low-latitude driving force superimposed on the high-latitude cold background. This rain belt rearrangement was most probably caused by an interaction between cold air advection and summer moisture transport across the tropical Pacific Ocean. Examination of high-resolution proxies suggests short-term climate fluctuations indicative of a global teleconnection involving moist air transportation patterns from the tropics to higher latitudes, varying with ENSO and other tropical factors.