Researchers from the McGill University and the University of Pennsylvania have found enough evidence to prove climate change is the real reason for the disappearance of ice-free locations, known as polynya, in the Arctic, according to a McGill University press release.
Polynya was first discovered in the Weddell Sea back in the 1970's and has not reappeared in the last 40 years. Scientists have since been examining its origins and researchers recently decided that its last appearance was likely its last, since climate change is trapping warm water under the ocean.
McGill researchers worked with their colleagues from the University of Pennsylvania to analyze tens of thousands of measurements made by robotic floats and ships in the ocean and all around Antarctica during the last 60-years, according to the news release.
"Deep ocean waters only mix directly to the surface in a few small regions of the global ocean, so this has effectively shut one of the main conduits for deep ocean heat to escape," said Casimir de Lavergne, according to the news release.
Lavergne is the lead author of the study and graduate of McGill's Master in Atmospheric and Oceanic Sciences.
The study proves that the ocean's surface has slowly been getting less salty since around the 1950's, according to the news release. The freshwater lid trapping the warmer waters are "increasing" due to more precipitation in the area.
The polar ocean has also become wetter, and the study may also help explain why the Antarctic Bottom Water has been declining during the past couple of years.
"The waters exposed in the Weddell polynya became very cold, making them very dense, so that they sunk down to become Antarctic Bottom Water that spread throughout the global ocean," said Eric Galbraith, study co-author and professor of McGill's Department of Earth and Planetary Sciences, according to the news release. "This source of dense water was equal to at least twice the flow of all the rivers of the world combined, but with the surface capped by freshwater, it has been cut off."
Their research was published in the March 2 issue of Nature Climate Change.
"Although our analysis suggests it's unlikely, it's always possible that the giant polynya will manage to reappear in the next century," Galbraith added. "If it does, it will release decades-worth of heat and carbon from the deep ocean to the atmosphere in a pulse of warming."
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