How do the ice-climate feedbacks lead to tipping points in the climate?
As we have just seen, the loss of sea ice in the Arctic Ocean is allowing much more solar radiation to be absorbed into the Arctic summer, causing a warming of the Arctic Ocean. But the principal circulation pattern of the Atlantic Ocean is strongly dependent on dense Arctic seawater sinking to make room for the warm surface current — the Gulf Stream — traveling northward from the tropics. Increased summertime warming of Arctic seawater, however, makes the water more buoyant and less inclined to sink. When the happens, there will be no room in the Arctic for warm water coming from the south — and the Gulf Stream will weaken or shut down. The consequence? A deep and enduring chill would descend over Western Europe. It may seem counterintuitive that warming of the Arctic could lead to a cooling of Western Europe, but Europe occupies a latitude band roughly similar to central Canada and central Asia, regions with much harsher climates. Europe is warmer than those colder regions because it
