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Source: NIWA – National Institute of Water and Atmospheric Research

Coldest, driest, windiest, iciest, highest, most southerly – Antarctica is a continent of extremes.

It’s bigger than Europe and has ice covering 98% of its land, at a hefty average thickness of nearly 2km. Holding 90% of the world’s ice and 80% of its fresh water, Antarctica has a profound effect on the planet’s oceans and climate.

Antarctica is also remarkable for its massive ice shelves, giant sheets that flow out from the continent and float on the surrounding sea.
The Ross Ice Shelf – the world’s largest – lies above the Ross Sea, almost due south of New Zealand.

It’s little surprise, then, to find three NIWA scientists, each working on Antarctic Science Platform research projects focused on trying to piece together the changes in the Ross Sea and the ice shelf above.

Dr Denise Fernandez’s research takes place where the Ross Sea meets the outer edges of the ice shelf, where Antarctica connects to the Southern Ocean and the rest of our planet beyond. She studies the interactions between the ocean, ice and atmosphere.

“We want to understand the mechanics of the Ross Sea and how it might change under different climate scenarios,” she explains.

Because ice shelves float, there is a continuous circulation of water underneath that comes in and out of the open ocean. You might presume that this is all cold, but some columns of water are comparatively warm and can cause ice shelves to melt from below. There is also salt present in the environment, which can have impacts on the ice. It’s these processes that Fernandez and her international colleagues are trying to figure out.

“We’re developing models to analyse the heat, salt and energetics of this water. How warm and cold is it? Is more warm water coming in? How will this affect melting? Changes have big implications for sea-level rise and ocean circulations around the world.”

Fernandez and her team use Argo floats, robotic instruments that collect data by drifting with the ocean currents. The floats move through the water column collecting information at different depths. Every 10 days they return to the surface and transmit their data to passing satellites. The floats can stay in the ocean for several years.

After analysing the Argo float information, they found that the coldest parts of the Ross Sea are near the surface, but there is an inflow of warm water below 2,000m. There is also a spike in salinity in this deeper region.

“The evidence from the Argo floats helps us to build simulations for various potential future climates, so we can see the implications of changing currents, temperatures and salinity on this delicate system,” she says.