Turning on the Atlantic heat pump

34 million years ago, the age – old greenhouse climate of the dinosaurs came to an end and the icy cold climate of today began. Antarctica was frozen for the first time, and geological data suggests that the stunning circulation of the southern Atlantic, the global oceanic treadmill of heat and nutrients warms Europe, also began at that time. Why, exactly, remained a mystery.

"We found a new trigger to explain the start of the Atlantic current system during the climate transition: during the warm climate, floating fresh water invaded the Arctic and prevented the sinking that feeds the conveyor.We found that the gateway to the Arctic and Atlantic was closed due to tectonic forces, which resulted in a dramatic increase in salinity in the & &…………… North Atlantic, resulting in a warming of the North Atlantic and Europe and the start of modern traffic that is heating Europe today, "said David Hutchinson. , a researcher in the Department of Geological Sciences at Stockholm University and lead author of the article published in Nature Communications.

The team of scientists at the Bolin Climate Research Center used a combination of geophysical and climate modeling data to show that freshwater transport across the Arctic-Atlantic Gateway plays a vital role in controlling traffic flow. .

"Not only did the deep waters begin to form in the Atlantic Ocean, but they also ceased to form in the North Pacific, which is consistent with geological evidence.We were surprised to see that our computer simulations could explain these two changes due to the salty ocean. " The currents that connect the Pacific to the Atlantic. Our study is the first to show that these two events are related, which is very exciting, "said Hutchinson.

The climate at that time was very hot, with atmospheric CO₂ two to three times the current levels, contributing to the freshness of the Arctic waters. The study raises the question of whether, in a warm world in which the Arctic could become very cool, sinking in the Atlantic could end, which could dramatically change the climate of Europe. Without the Atlantic treadmill, Europe can experience colder winters and warmer, drier summers, creating a more extreme and inhospitable climate.

"Our study contributes to bridging the gap between climate modeling and deep geological observations, and we hope this will inspire new research from both communities on the deep circulation of the ocean," said Hutchinson.

The article "The closure of the Arctic as a trigger for the overthrow of the Atlantic during the Eocene-Oligocene transition" is published in the scientific journal Nature Communications.