Dansgaard-Oeschger Cycles and Heinrich Events

The following 4 graphs show the delta O-18 data for ice core from the GISP2 hole in central Greenland. The time scales represented are:

1) 0-125 ka (including the present interglacial, the most recent glacial and the last interglacial periods)

2) 10-50 ka (showing the very significant T fluctuations – Dansgaard-Oeschger cycles - of the middle of the last glacial period)

3) 27-37 ka, showing some of the more extreme Dansgaard-Oeschger cycles in more detail. (Note the rapid (< 200 y) changes.)

4) 10-65 ka, also showing the Heinrich events that have been delineated during that period.

Also included is a figure from the paper by Richard Alley (Palaeoclimatology:  Icing the North Atlantic, Nature 392, 335-337, 26 March 1998), which he uses to explain his version of the link between DO cycles and Heinrich events.