Antarctica glaciers making seawater less salty, more buoyant

Rodiano Bonacci
Aprile 20, 2018

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.

According to the study, in Antarctica, the warmer oceanic water gets trapped beneath the cold fresh water that comes from melting glaciers and this results in the warm oceans calving out more ice from under the massive shelves. "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".

"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", said Silvano, reports Science Daily.

"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", Silvano said.

"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", he explained. Greenland has caused three times more sea level rise than Antarctica so far, but ice melt on the southern continent is responsible for more of the acceleration.

Two feet of sea level rise by the end of the century "would have big effects on places like Miami and New Orleans, but I don't still view that as catastrophic" because those cities can survive - at great expense - that amount of rising seas under normal situations, Nerem said.

"Does this further enhance melting of the ice sheet or does the could fresh water slow it down?" Similar scenario in a previous study More recently, as reported in Digital Journal, Researchers, led by University College London (UCL) and the Woods Hole Oceanographic Institution (WHOI) provided compelling evidence that the Atlantic Ocean's circulation - called Atlantic meridional overturning circulation (AMOC) - has been slowing down. According to the researchers, the melting glaciers hinder the deep mixing process of ocean water. The found out that the waters at the ocean surface were less salty and more buoyant and this indicated that the Antarctic waters have been altered.

"What is clear is that different regions of Antarctica are behaving in different ways, and if we are to understand how fast the ice sheet will melt and contribute to future sea-level rise we need to understand the processes of ocean circulation on the ice sheet margin at the local scale".

The wider West Antarctic Ice Sheet stores an equivalent 3.2m of sea level rise, while the much larger East Antarctic Ice Sheet is estimated to contain 58m of equivalent sea level rise.

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