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Antarctic Ice Shelves: What lies beneath?


Ice shelves fringe much of the coastline of Antarctica. They are vast slabs of ice which stretch out from the coast, still fixed to the continent but floating on the ocean surface.  When approached by ship or on foot across the frozen sea, they may tower several hundred meters above you. I previously spent several months living and working on the Brunt Ice Shelf in Antarctica. Here’s a bit more about ice shelves…

Ice shelf, Antarctica © Dr Susie Grant, BASIce shelf, Antarctica © Dr Susie Grant, BAS

Ice shelves flow out from the continent, ‘fed’ by inland glaciers. At their seaward edge, they periodically ‘calve’ vast icebergs. These bergs can be the size of small countries.

In a stable system, there is a near-perfect natural balance between the flow and loss of ice. But warmer temperatures are already destabilizing this system along the Antarctic Peninsula, one of the fastest warming places on our planet. Ice shelves are particularly sensitive to climate change because they are warmed by increasing air temperatures from above and increasing ocean temperatures from below.

This warming can result in the disintegration, retreat or catastrophic collapse of ice shelves. This was most dramatically witnessed between January – March 2002 when approximately 3,250 square kilometers of the Larsen B on the east coast of the Antarctic Peninsula collapsed, releasing 720 billion tons of ice into the Weddell Sea. That’s a lot of ice!

Ice shelves locations © Ted Scambos, NSIDCIce shelves locations © Ted Scambos, NSIDC

When an ice shelf collapses or retreats significantly, it exposes a new area of the ocean. This in turn provides new habitat and may lead to the colonisation of the seabed by new marine species. So these are vitally important and unique study areas for scientists, such as Dr Susie Grant, my former colleague at the British Antarctic Survey.

“These areas present outstanding opportunities for science’ Susie tells me. ‘They could give us really important insights into how different species colonise marine areas, and how new biological communities develop over years, or even decades” –  Dr Susie Grant.

That’s one of the reasons we are this week meeting at CCAMLR, the international forum responsible for conservation and fisheries management in the Southern Ocean, to negotiate the adoption of Special Areas for Scientific Study which would be triggered when ice shelves collapse in the future and expose new areas of the ocean.

Emperor penguins on sea ice below the Brunt Ice Shelf © British Antarctic SurveyEmperor penguins on sea ice below the Brunt Ice Shelf © British Antarctic Survey

If CCAMLR adopts this proposal now or in the future , it would mean that commercial fishing in these areas would be completely banned, initially for 10 years, to give the scientific community the chance to study ‘what lies beneath’, and to decide how best to manage this critical habitat into the future.

Find out more about what WWF does in the Antarctic

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