The mystery of the last ice age finally solved

Around 100,000 years ago, ice covered large areas of the northern hemisphere. The disturbed orbit of our Earth can explain this phenomenon of glaciation. But only in part. To understand the details, the researchers had to perform sophisticated simulations.

Throughout its history, our Earth experienced several glaciations. Periods during which large areas of its northern hemisphere became covered in ice. It happened, for example, about 100,000 years ago. In a few thousand years, the mountain glaciers then developed spectacularly to form ice caps spanning much of Canada, Siberia and northern Europe.

How could this have happened? For this time, due to the natural variations of theorbit of our Earth, say scientists. With the result, a summer cooling on the side of thenorthern hemisphere triggering a general glaciation. But there is a shadow on the board. Because this phenomenon does not appear sufficient to cover northern Europe with ice.

Because the North Atlantic Current – also known as the Gulf Stream – tends to carry warm waters on the coasts of the north-west of our continent. Thus in general, Scandinavia, although situated at a latitude similar to that of the Canadian Arctic, has temperatures too high for ice to form.

Models not only good at predicting the future

To understand how ice caps could still have appeared in northern Europe around 100,000 years ago, researchers from theuniversity of arizona (USA) have developed an extremely complex Earth system model. What to recreate in a very realistic way, the conditions which existed at the beginning of this ice Ageand show the essential role of thearchipelago Canadian arctic in the process.

The simulations reveal that as long as the ocean remains open in the region, an ice sheet cannot form over Scandinavia. On the other hand, if the ice comes to block the waterways of the Canadian Arctic Archipelago, cold water from the Arctic and the North Pacific is diverted to Greenland. It all slows down ocean circulation depth of the North Atlantic and brings conditions weather report cooler in northern Europe. The recordings of sediment sailors seem to confirm it. They indeed show convincing evidence of a weakened circulation before the formation of the glaciers in Scandinavia.

A way of using models that therefore goes a little beyond their traditional objective of predicting the climates of the future to rather decipher the interactions of the past. Interactions that could also apply to others ice ages what our Earth has experienced. And even at the shortest periods like the one that happened about 13,000 years ago.