MIAMI — While the Earth is getting warmer, the water is actually getting colder in a subpolar North Atlantic region called the “warming hole.” Although some scientists predict that changing ocean temperatures like this could lead to sudden climate change events — like in the movie “The Day After Tomorrow” — a new study says that’s not necessarily what we’re seeing here.
Researchers from the University of Miami report that the warming hole is not the result of a slowdown in ocean currents, as past scientists have suggested. The Atlantic Meridional Overturning Circulation (AMOC) is a system of ocean circulation that redistributes heat through the oceans by carrying warm water from the tropics and into the North Atlantic.
“However, our study shows the warming hole during the past century is unlikely due to a slowdown of the AMOC. Instead, the warming hole is actually a consequence of human driven changes in the atmosphere” says Chengfei He, a postdoctoral researcher in the Department of Atmospheric Sciences at the Rosenstiel School, in a university release. “Our finding suggest that this warming hole will not result in an abrupt climate change event lethal to humans as depicted in Hollywood movies.”
Prior AMOC slowdowns have led to abrupt climate change events in the past, according to geological records found in ice core samples in Greenland.
“The warming hole is believed as a fingerprint of the AMOC in present day. Its appearance suggests the AMOC may not be stable. Our results do not support this idea,” says study co-author Amy Clement, a professor in the department of atmospheric Sciences at the University of Miami.
The warming hole has been cooling for 100 years
The team used a new climate model to study the pattern of temperature changes in a body of water in the subpolar North Atlantic region. The warming hole appears to be cooling down over the past century. That model involved a digital Earth that reproduced past climate changes and future climate change events.
More specifically, the model simulated a motionless ocean to study how North Atlantic temperature is impacted by atmospheric changes from excess greenhouse gases and aerosol emissions. With no circulating currents in the ocean, changes in ocean surface temperature would have to come from atmospheric conditions.
When the model simulated an Earth under global warming, the atmospheric westerlies shifted north. This caused local winds to breeze over the subpolar North Atlantic, most likely triggering the warming hole.
“This cooling trend is partially compensated by the warming due to the rise of greenhouse gases and the damping effect in sea surface temperatures,” the study authors conclude.
The study is published in the journal Geophysical Research Letters.