Huge blocks of sea ice that melted in the Arctic and then flowed into the North Atlantic contributed, during various phases in the past but especially from 8,000 to 13,000 years ago, to the development of abrupt climate change following the last ice age.
This is the opinion of researchers at the University of Massachusetts at Amherst and the Woods Hole Oceanographic Institution who have published their study on Geology.
After the end of the last ice age, there were in fact several cold phases that most researchers had difficulty explaining.
In particular, a very cold period, about 12,900 years ago, known as the recent Dryas, was problematic enough to explain so much that several scientists proposed meteorite impacts or heavy global volcanic eruptions to explain the change.
Some even thought that the recent Dryas was triggered by the drying up of Lake Agassiz, a large glacial lake near the ice cap that once stretched from the south of the Arctic to the area of today’s New York City.
According to Alan Condron and Raymond Bradley, two of the authors of the study, it is the periodic ice breakage of the Arctic Sea that is known to influence the global climate and lead to these cold periods.
This melting ice would cause freshwater flooding in the seas near Greenland, Norway and Iceland, which would have happened several times between 13,000 and 8,000 years ago.
These processes would have slowed down a major ocean current called the “southern reversal of Atlantic circulation” (AMOC), which brings warm salt water to the North Atlantic and pushes cold fresh water to the South.
The amount of cold and fresh water, in particular, would have been so high during these phases that it would have triggered abrupt global cooling, such as the recent Dryas.
This quantity would be so high that it would also exceed the hypothesis of Lake Agassiz, whose amount of water would not have been sufficient to trigger a global cooling phenomenon.
“Our results show that ice from the Arctic Ocean itself may have played an important role in causing abrupt climate change in the past,” the researchers explain.
Also because in the past the Arctic Ocean was covered by much thicker ice layers than we have seen in recent decades, which have become increasingly smaller due to ongoing global warming. Freshwater quantities so large that they were able to slow down AMOC and introduce a cooler climate globally.