Climate change has put a “freshwater lid” on part of the Antarctic ocean, causing a huge ice-free zone from the region to disappear.
Researchers at McGill University, Canada suggested that heat from the depths of the ocean is being trapped under the Antarctic ice shelf and this could be another effect of climate change.
A “freshwater lid” has probably caused this ice-free region, or polynya, to close, according to the researchers who published their findings in a paper titled “Cessation of deep convection in the open Southern Ocean under anthropogenic climate change” in Nature Climate Change.
In the 1970s, researchers in Antarctica found an open body of water about the size of New Zealand within an ice pack in the Southern Ocean’s Weddell Sea.
Eric Galbraith, co-author of the study said, “The fact that we can still have a surprise like this after studying the climate system for decades shows just how complex and dangerous climate change is.”
Before this, researchers were of the view that phenomenon, known as the Weddell polynya, was a rare occurrence.
However, the study says the polynya has not reappeared in the nearly 40 years since it closed due to the effects of the rising temperature on ocean salinity.
The researchers have held global warming responsible for the phenomenon.
The study, which was published in Nature Climate Change, said that polynya is unlikely to reappear.
If it does, nearly 40-years worth of heat and carbon dioxide will be released from the depths of the ocean.
The increase in precipitation in the Southern Ocean and simultaneous melting of glaciers in Antarctica region, the ocean have flooded with large amounts of freshwater and prevented the warm water underneath from rising to the top,” it explained.
To study what caused its disappearance, scientists examined climate models which indicate that as levels of carbon dioxide in the atmosphere increase, precipitation changes.
“This agrees with the observations, and fits with a well-accepted principle that a warming planet will see drier regions become drier and wetter regions become wetter,” Professor Jaime Palter, from McGill University’s Department of Atmospheric and Oceanic Sciences and co-author of the study said in a press release.
