Ice shelf at double risk

    New study shows Antarctic ice shelf is thinning from above and below.
    A decade-long scientific debate about what’s causing the thinning of one of Antarctica’s largest ice shelves is settled this week (Wednesday 13 May) with the publication of an international study in the journal The Cryosphere.

    10009624-bas-radar-sledge-on-the-larsen-ice-shelf
    BAS RADAR Sledge on the Larsen Ice Shelf (Photo: Adam Clark, British Antarctic Survey)

    The Larsen C Ice Shelf — whose neighbours Larsen A and B, collapsed in 1995 and 2002 — is thinning from both its surface and beneath. For years scientists have been unable to determine whether it is warming air temperatures or warmer ocean currents that were causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse. This new study takes an important step forward in assessing Antarctica’s likely contribution to future sea-level rise.

    The research team combined satellite data and eight radar surveys captured during a 15-year period from 1998–2012. They found that Larsen C Ice Shelf lost an average of 4 metres of ice, and had lowered by an average of one metre at the surface.

    Lead author, Dr Paul Holland from British Antarctic Survey (BAS), says:

    “What’s exciting about this study is we now know that two different processes are causing Larsen C to thin and become less stable. Air is being lost from the top layer of snow (called the firn), which is becoming more compacted — probably because of increased melting by a warmer atmosphere. We know also that Larsen C is losing ice, probably from warmer ocean currents or changing ice flow.

    “If this vast ice shelf — which is over two and a half times the size of Wales and 10 times bigger than Larsen B — was to collapse, it would allow the tributary glaciers behind it to flow faster into the sea. This would then contribute to sea-level rise.”

    The Antarctic Peninsula is one of the fastest warming regions on Earth, with a temperature rise of 2.5°C over the last 50 years.

    read more… – British Antarctic Survey (BAS)

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