Glacial Inception

During the Quaternary the Earth experienced several glaciations. The last glacial inception happened 116,000 years ago. Most of the ice formed in North America. In our model glacial inception appears as a bifurcation transition from interglacial to glacial climate state caused by slow changes in the Earth's orbital parameters. On Quaternary time scales, this transition is very rapid, because it is amplified by snow-albedo feedback. Nearly all of the ice area in North America developed in about 1000 years only.

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Heinrich Events

Heinrich events (HEs) are large scale surges from the Laurentide ice sheet during glacial times. They appear if the basal ice over Hudson Bay and Hudson Strait reaches the melting point and begins to slide rapidly over the slippery ground. HEs belong to the most interesting phenomena in the climate system. During a HE sea level rose by several meters in some hundred years and the thermohaline circulation in the Atlantic broke down leading to cooling in a broad region of the Atlantic. A better understanding of this instability of palaeo ice sheets is vital for an assessment how today's ice sheets might behave in the future.

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Glacial Cycles

A further step towards an understanding of Quaternary climate change is the simulation of glacial cycles. The animation shows the last four glacial cycles from such a model simulation. The ice mainly starts to builds up over Baffin Island and Scandinavia. At the glacial maxima, vast regions of the Northern Hemisphere were covered with ice. In the animation, one can even see a slight separation between the Laurentide and Cordilleran ice sheet. Alaska and north eastern Eurasia remain mostly ice-free. During the terminations, the ice in North America retreats in north east direction. Our ice-age simulation agrees essentially with geological findings.

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