Clive R. McMahon

The elephant seal can dive to depths of 2,400 meters, making it the perfect animal to collect data on melting Antarctic ice shelves.

By strapping monitoring devices to the animals, which can weigh up to 3,000kg, researchers have been able to show that freshwater from the ice shelves is suppressing the creation of bottom waters that drive heat around the planet.


Sensor-clad seals are tracking Antarctic ocean change in real time Climate Change Sensor-clad seals are tracking Antarctic ocean change in real time

Antarctic bottom water is one of the densest water masses in the world's oceans and being the coldest bottom water, it is involved in the movement of the world's oceans. When sea ice freezes it leaves salt behind and the additional salt makes the water denser, causing it sink.

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Research reported in Nature says an increasing global heat suggests that bottom water formation could be stopped by a greater amount of freshwater coming from the melting ice shelves. Effectively, more fresh water being injected into the environment means the dense, salt-laden, water is diluted.

"We know this ice shelf is melting and we know it is accelerating, we think this dilution and freshing effect is likely to be ongoing into the future," Guy Williams, the lead author of the research from the University of Tasmania told WIRED.


"The implication from the study is ultimately that the density of the shelf waters may be reduced. It's the first direct evidence of the balance between the freshing and solidification in some of these regions."

Clive R. McMahon

Using the monitoring devices attached to around 20 to 30 elephant seals – tagging takes place as part of a wider project – the researchers were able to look at data on water temperature and salinity.

"Traditionally we'd use a ship, or put a mooring in with an instrument, but the seals were acting like a mooring as they were staying in one location and going up and down during their dives and collecting information," Williams said.


Clive R. McMahon

Seal data was collected across the Prydz Bay region of Antartica. Williams explained that without the seals it would have been practically impossible to collect the data from "places that no ship has ever visited"

In the research paper the international team, which includes researchers from across Australia, Denmark, Sweden, and Japan, says the data collected by the seals shows the "susceptibility of Antarctic bottom water" to the melted water. They write it shows "ultimately the potential collapse of Antarctic bottom water formation in a warming climate."