A mysterious “cold spot” in the ocean has long puzzled scientists. The latest study claims that this is an ominous sign, writes “CNN”.
The “cold spot” appears in a data visualization showing average temperatures in 2015 compared to 1951-1980. annual average
NASA’s Science Visualization Studio Goddard Space Flight Center for data.
In the North Atlantic, south of Greenland and Iceland, a large patch of water is doing something very strange. While the rest of the ocean warms, it gets colder. Scientists say they have the answer to this mystery, and it’s an ominous sign that the world is approaching one of the most alarming climate tipping points.
A band of ocean known as the “cold ball” or “warming hole” has cooled by nearly 1 degree Celsius (1.8 Fahrenheit) since 1900.
Scientists have long debated whether the anomaly is caused by heat loss from the ocean surface due to changes in winds and clouds, or whether it signals a weakening of a critical system of ocean currents that transports heat.
The Atlantic Meridional Overturning Circulation, or AMOC, acts like a vast ocean conveyor belt that pulls warm water from the tropics to the Northern Hemisphere, where it cools, sinks, and flows back south.
Many studies show that this system weakensas human-induced global warming melts ice and causes an influx of freshwater into the ocean, upsetting the AMOC’s delicate balance of warmth and salinity. Some scientists warn that the AMOC is heading toward a tipping point, possibly as early as this century, which would mean a collapse in the future.
A shutdown of the AMOC would be a global catastrophe, causing accelerated sea level rise along the US East Coast, plunging Europe into a winter deep freeze and displacing monsoons in Africa, causing prolonged periods of drought.
Some interpret the cold drop as a fingerprint of changes in the AMOC, since this is the region to which the AMOC brings much of its heat.
To better understand what’s happening in this part of the Atlantic, the study scientists combined real-world ocean heat data from instruments and satellites with climate models.
They found that the cooling of cold droplets occurs not only at the surface, but also deep in the ocean, where atmospheric conditions such as wind and clouds have a much weaker influence.
All signs point to an AMOC influence, study finds. “It changes the heat transfer of the ocean,” which contributes to the cooling of the cold droplet, said Stefan Ramstorf, a study author and professor of physics and oceans at the University of Potsdam in Germany.
