Seals reveal icy secret
Some high-tech elephant seals have helped confirm that fresh water from Antarctic’s melting ice shelves affect global temperatures.
A new study says the fresh water from melting shelves slows the processes responsible for the formation of deep-water ocean currents, which regulate global temperatures.
The research was made possible by a set of seals that were outfitted with sensors and satellite-based science gear.
Dr Guy Williams from the Institute of Marine and Antarctic Studies and Antarctic Climate and Ecosystems CRC says the findings raise questions about potential future changes in global ocean circulation patterns.
“Antarctica and the Southern Ocean are like a beating heart, producing deep and powerful currents of cold water that drive global ocean mixing and regulate atmospheric temperatures,” Dr Williams said.
“These currents begin with intense sea ice formation around the Antarctic continent in winter, which creates cold, salty and dense water that sinks and flows away from the continent in large volumes.
“If this production of Antarctic bottom water weakens, it leads to changes in global ocean circulation patterns that can, in turn, lead to changes in the global climate.”
In 2011, the same team of researchers discovered a fourth source of Antarctic Bottom Water off Cape Darnley in East Antarctica.
The latest research published today, including an additional two years of data, shows that Prydz Bay makes an important secondary contribution to Cape Darnley Bottom Water.
“However we found that the contribution from Prydz Bay is less salty and dense due to the influence of nearby ice shelves,” Dr Williams said.
“We can easily imagine that the production of these global ocean currents will slow as the rate of ice shelf melting all around Antarctica continues to increase.”
Since 2011, elephant seals at Antarctica’s Davis Station have been outfitted with instruments including oceanographic sensors, as part of Australia’s Integrated Marine Observing System (IMOS), supported by the Australian Government.
When the tagged seals surface, their sensors relay information back to land via satellite, and the near real-time data becomes available via the IMOS data portal. The oceanographic data collected by the seals is also used for ecological research into their behaviour and aids in conservation
“This study would have been virtually impossible without help from the seals, who can gather oceanographic data from areas that tend to be very difficult to access in research ships,” Dr Williams said.
“Seals have the advantage of continuing to forage and record ocean properties through the winter, exploiting small cracks and leads in the sea ice cover to breathe and allow for data transmission.
“To instrument each region with traditional moorings would be prohibitively expensive.”
“The seals are doing an outstanding job and the result is an important advance in our understanding of the global ocean system.”