A new source of Antarctic ice melt has been identified by scientists, who fear that this could lead to sea levels rising faster than once expected.
In a study published in the journal Science Advances, a team led by University of Tasmania Institute for Marine and Antarctic Studies (IMAS) researchers looked at a previously undocumented phenomenon, where glacial meltwater reduces the salt content of the ocean’s surface layer. This makes the surface layer float more easily, effectively preventing it from mixing with colder winter waters, and allowing deeper waters to retain their warmth. This all adds up to Antarctic glaciers melting faster than what once was thought.
As quoted by Science Daily, study lead author and IMAS doctoral student Alessandro Silvano explained that the phenomenon is similar to how oil will always float on top of water when both liquids are mixed in a container.
“The same happens near Antarctica with fresh glacial meltwater, which stays above the warmer and saltier ocean water, insulating the warm water from the cold Antarctic atmosphere and allowing it to cause further glacial melting.”
Silvano added that this rise in glacial meltwater in Antartica causes ice from shelves to melt even more, thus leading to a more pronounced sea level rise.
The researchers also discovered that the presence of fresh meltwater could slow ocean circulation in some parts of Antarctica, further driving ice melt by preventing dense water from forming and sinking, as atmospheric carbon dioxide is drawn below the ocean.
“In combination, the two processes we identified feed off each other to further accelerate climate change,” Silvano warned.
According to a report from the Independent, the IMAS study came on the heels of another paper, where University of Leeds researchers discovered that it took just five years for a large chunk of underwater ice to melt off the bottom of Antarctica’s ice shelves. It is these shelves that serve as a buttress for the continent’s massive ice sheet, and with the “positive feedback loop” leading to warmer waters flowing below the shelves, Silvano and his colleagues believe that this new source of Antarctic ice melt could lead to further thinning and fragmentation.
In addition to the newly published findings, the Independent also noted that a similar positive feedback loop is thought to have brought about abnormally high levels of sea level rise about 15,000 years ago. As for the current feedback loop, Silvano cautioned that the phenomenon is “already underway,” and that this could cause the world’s sea levels to rise sooner than once thought.