39. MODELLING THE END OF AN INTERGLACIAL (MIS 1, 5, 7, 9, 11)

Abstract

With the CLIMBER-2 model, the last glacial inception is simulated as a rapid ice-sheet expansion over northern North America, with only little ice sheets in Scandinavia. We present sensitivity studies that more deeply investigate the climatic feedbacks at the end of an interglacial. (i) An ice-free Greenland during the Eemian appears as a second stable state in the model. The initial size of the Greenland ice sheet, however, has only little effect on the subsequent glacial inception. (ii) North American glaciation can be reduced or even suppressed using preindustrial or Eemian vegetation and/or ocean surface conditions. (iii) Timing and amplitude of the last glacial inception cannot be estimated by the use of time-slice simulations. (iv) Changes in precession (perihelion) are crucial for the ice-sheet growth, obliquity and CO2 merely act as amplifiers. (v) Cold events at the end of the interglacial can be reproduced by the introduction of freshwater disturbances into the North Atlantic. (vi) The model is able to simulate earlier glacial inceptions as well, although difficulties exist with respect to the strength of the glaciation. Future glacial inception in the model happens only in about 50 000 years from now. © 2007 Elsevier B.V. All rights reserved.