Study reveals new Antarctic process contributing to sea level rise and climate change

April 18, 2018, University of Tasmania
The Mertz Glacier in January 2017. Credit: Alessandro Silvano

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.

Led by IMAS PhD student Alessandro Silvano and published in the journal Science Advances, the research found that glacial meltwater makes the 's surface layer less salty and more buoyant, preventing deep mixing in winter and allowing 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 and hence an increase in sea level rise."

The study found that fresh also reduces the formation and sinking of dense 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.

Katabatic winds on the Ross Sea, Antarctica, May 2017. Taken during a rare winter voyage to the Antarctic on US icebreaker Nathan B Palmer. Credit: Guy Williams
"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 this feedback process is not only possible but is in fact already underway, and may drive further acceleration of the rate of in the future.

"Currently the ice shelves resist the flow of ice to the ocean, acting like a buttress to hold the ice sheet on the Antarctic continent.

"Where warm ocean waters flow under the ice shelves they can drive rapid melting from below, causing ice shelves to thin or break up and reducing the buttressing effect.

"This process leads to rising sea levels as more ice flows to the ocean.

"Our results suggest that a further increase in the supply of to the waters around the Antarctic shelf may trigger a transition from a cold regime to a warm regime, characterised by high rates of melting from the base of ice shelves and reduced formation of cold bottom waters that support ocean uptake of atmospheric heat and ," Mr Silvano said.

Explore further: Antarctic seawater temperatures rising

More information: "Freshening by glacial meltwater enhances melting of ice shelves and reduces formation of Antarctic Bottom Water" Science Advances (2018).

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4.6 / 5 (10) Apr 18, 2018
Obviously the scientists involved in this expedition braved the antarctic ocean in the winter merely to keep their funding intact. Just so they can continue to earn 1/3 to 1/2 of what they could earn in a nice comfortable office working in industry. After all, they are being driven solely by ideology right?

Anyone in agreement with that first paragraph needs to have their head examined. They are in serious danger from a complete cranial collapse due to vacuum implosion.
1 / 5 (4) Apr 18, 2018
No mention of volcanic activity under Antartica?
Hard for CO2 to trap heat when there is zero sunlight?
Nice video.
The wind chill factor is?
Why are the scientists not on the deck, enjoying the "warming" induced by the CO2?
1 / 5 (1) Apr 19, 2018
I can only assume you two gays have some kind of political motive for verbally trashing perfectly good science and the scientists that conducted it. Its part of your religion that there isn't such thing as man made global warming. But your moronic rhetorics convince no scientists here. Sorry! You fail!
1 / 5 (2) Apr 19, 2018
Scientists discover 91 volcanoes below Antarctic ice sheet.

Volcanic activity would be the driver of Glacier melt, not man-made CO2, just a guess?
1 / 5 (2) Apr 19, 2018
vostok surface temperature, any warming? -30
1 / 5 (2) Apr 19, 2018
How much has the ocean "Antartica" warmed in the last 20 years.
0.1 degrees?
Why not publish the temps of this massive change in Antarctica's ocean temp?
5 / 5 (2) Apr 19, 2018
the amount of heat evolved in oceans is way larger than this one in atmosphere.
Which is quite strange, because in anthropogenic global warming model the primary source of heat is carbon dioxide within Earth atmosphere.


NO, it isn't strange at all. Not if you at least know extremely basic physics. The reason why more heat energy is in the oceans is because, regardless of global warming, something called the 'heat capacity' of water is much higher than that of air (if you don't believe me, just google it for yourself). That combined with the mass of the oceans being much more than that of the atmosphere means the oceans act as the main sink for heat energy in the biosphere that completely dwarfs that of the atmosphere.

+ more CO2 in the atmosphere INDIRECTLY warms the oceans by first warming the atmosphere and then heat from the air defuses into water; what is hard to understand about that? You do understand warm air can warm water, right?
1 / 5 (2) Apr 19, 2018
humy, i assume you heat your morning coffee with a 20 W light bulb
not rated yet Apr 19, 2018
humy, i assume you heat your morning coffee with a 20 W light bulb

No, I don't dip a 20 W light bulb into my coffee to heat it.

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