Willi Dansgaard made the landmark discovery that the oxygen isotope profile in ice cores provided a long-term record of changing air temperature in the Polar regions. Ice core records from Greenland and Antarctica also showed rapid climate change and sequences of abrupt warming and cooling cycles within the last glacial stage. ‘Ice cores, abrupt climate shifts, and ecosystem change’ also outlines the fundamental role of ocean thermohaline circulation in regulating global climate. How did ecosystems and humans respond to these abrupt changes? What role did they play in the demise of the ice age megafauna? Late Pleistocene ecosystems and extinctions and the spread of modern humans in the last glacial are considered.