SMITHSONIAN MAGAZINE - Just south of Greenland, in the northern Atlantic Ocean, a strange area of water has been confounding scientists for years. While the rest of the ocean warms, that patch has been mysteriously cooling. Researchers have offered different theories behind this “cold blob,” such as changes in ocean circulation patterns or aerosol pollution in the atmosphere.
Now, two recent studies are shedding more light on the phenomenon, adding to existing evidence that the slowdown of a key ocean current system is producing the cool region.
The cold blob—also known as a warming “hole”—can be spotted on maps of Earth’s changing surface temperature, appearing as a blue dot of cooling in a sea of red heat. As the water around it warms, the blob’s temperature has been steadily dropping by up to 0.5 degrees Fahrenheit.
Researchers at the University of California, Riverside (UCR), looked at 20 years of observations of the Atlantic Meridional Overturning Circulation (AMOC), a system of ocean currents that circulate in the Atlantic Ocean. Then, they used 100 years of temperature and salinity data to reconstruct the ocean dynamics from before official records began. They published their work in the journal Communications Earth & Environment in May.
“People have been asking why this cold spot exists,” co-lead author Wei Liu, a climate scientist at UCR, says in a statement. “We found the most likely answer is a weakening AMOC.”