A new IMAS-led study has revealed a previously undocumented process where melting glacial ice sheets change the ocean in a way that further accelerates the rate of ice melt and sea level rise.
(From Phys.org) — Led by IMAS PhD student Alessandro Silvano and published in the journal Science Advances, the research found that glacial meltwater makes the ocean‘s surface layer less salty and more buoyant, preventing deep mixing in winter and allowing warm water at depth to retain its heat and further melt glaciers from below.
“This process is similar to what happens when you put oil and water in a container, with the oil floating on top because it’s lighter and less dense,” Mr Silvano said.
“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.
“We found that in this way increased glacial meltwater can cause a positive feedback, driving further melt of ice shelves and hence an increase in sea level rise.”
The study found that fresh meltwater also reduces the formation and sinking of dense water in some regions around Antarctica, slowing ocean circulation which takes up and stores heat and carbon dioxide.
“The cold glacial meltwaters flowing from the Antarctic cause a slowing of the currents which enable the ocean to draw down carbon dioxide and heat from the atmosphere.
“In combination, the two processes we identified feed off each other to further accelerate climate change.”
Mr Silvano said a similar mechanism has been proposed to explain rapid sea level rise of up to five metres per century at the end of the last glacial period around 15 000 years ago.
“Our study shows that…
Read the full article here: https://phys.org/news/2018-04-reveals-antarctic-contributing-sea-climate.html