The last glacial termination

A major puzzle of paleoclimatology is why, after a long interval of cooling climate, each late Quaternary ice age ended with a relatively short warming leg called a termination. We here offer a comprehensive hypothesis of how Earth emerged from the last global ice age. A prerequisite was the growth of very large Northern Hemisphere ice sheets, whose subsequent collapse created stadial conditions that disrupted global patterns of ocean and atmospheric circulation. The Southern Hemisphere westerlies shifted poleward during each northern stadial, producing pulses of ocean upwelling and warming that together accounted for much of the termination in the Southern Ocean and Antarctica. Rising atmospheric CO2 during southern upwelling pulses augmented warming during the last termination in both polar hemispheres. At the peak of the last ice age, expansiveice sheets covered large areas of theNorthern Hemisphere (NH) (Fig. 1). The reduction of this continental ice to about its present volume represents one of the largest and most rapid natural climate changes in Earth’s recent history. As a consequence, identifying the con-ditions and processes that triggered this degla