Seals help scientists survey Antarctica's disappearing glaciers

For the first time, scientists have manage to captured a full-depth portrait of glacial melting during winter -- with the help of some local residents.

The breakthrough, detailed Friday in the journal Communications: Earth and Environment, was made possible by a team of deep-diving seals with instruments strapped on their heads.

Winter in Antarctica is harsh, making research expeditions too difficult, and satellites can only provide so much detail.

Because glaciers are partially submerged, researchers need to gather underwater observations to understand the full scope of glacial melting.

Using temperature and salinity data recorded by the instruments carried by the seal team, scientists were able to map meltwater outflows from Pine Island Glacier, a massive glacier flowing into the Amundsen Sea from Antarctica's west coast.

"The temperature and salinity of water change everywhere glacial meltwater exists," lead author Yixi Zheng, a postgraduate researcher at the University of East Anglia, said in a news release. "Just like looking for a 'fingerprint' of glacial meltwater, we use temperature and salinity data to track the glacial meltwater."

The data revealed two distinct meltwater-rich layers in the water column -- one at a depth of approximately 250 meters, or 820 feet, and another at 450 meters, or 1,500 feet.

Scientists determined the two layers are linked by an array of meltwater-rich columns.

Pine Island Glacier is the fastest-melting glacier in the world. As its meltwater flows into the sea, it spreads out and then rises, creating pockets of warm water that keep portions of the Amundsen Sea free from ice.

"As the glacial meltwater is warmer and fresher than the ambient water, it is lighter than the ambient water and more likely to rise up," Zheng said.

"It brings heat and nutrients such as iron to the near surface, which may melt the sea ice near glaciers and increase the nutrient level near the surface. This enhances the air-sea interactions, and the meltwater-related nutrient may boost the growth of marine planktons like algae," Zheng said.

In addition to revealing the scope of glacial melting, the latest findings could help researchers better understand local water circulation patterns that influence nutrient cycling.

Scientists suspect meltwater flows bring nutrients to the surface, fueling springtime phytoplankton blooms.

By keeping coastal waters free of sea ice, rising columns of meltwater may also help warm water currents encroach upon coastal glaciers -- a kind of melting feedback loop -- scientists said.

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