New research has revealed that the melting ice sheet in Antarctica may recede far more quickly than previously anticipated.
The proof comes in the form of seafloor traces off the coast of Norway that show the retreat of a vanishing European ice sheet thousands of years ago.
The glaciers in Antarctica that are receding the fastest are now seen to do so at a rate of up to 30 metres per day.
However, if they accelerated, the additional meltwater would have significant effects on sea level rises all throughout the world.
Since the 1990s, the surface of the world’s oceans has already risen by almost 1 centimetre due to ice loss from Antarctica brought on by climate change.
The maximum retreat with the Norwegian sheet, according to the researchers, was more than 600m per day.
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“This is something we could see if we continue with the upper estimates for temperature rise,” explained Dr Christine Batchelor from Newcastle University, UK.
“Although, worryingly, when we did the equations to think about what would be needed to instigate such retreat in Antarctica, we actually found there are places where you could get similar pulses of withdrawal even under the basal melt rates we know are happening at the moment,”
Dr Batchelor and colleagues report their research in this week’s edition of the journal Nature.
The team has been looking at a great swathe of seafloor off the central Norwegian coast. Twenty thousand years ago, this area was witness to a massive Northern European ice sheet in the process of withdrawal and break-up.
The sheet’s past existence is written into more than 7,600 parallel, ladder-like ridges that have been sculpted in the seafloor’s muddy sediments. These corrugations are less than 2.5m high and are spaced between about 25m and 300m apart.
Scientists interpret the ridges to be features that are generated at an ice grounding zone.
This is the zone where glacier ice flowing off the land into the ocean becomes buoyant and starts to float. The corrugations are created as the ice at this location repeatedly pats the sediments as the daily tides rise and fall.
For the pattern to have been produced and preserved, the ice must have been in retreat (advancing ice would destroy the ridges); and the tidal “clock” therefore gives a rate for this reversal.
Story adapted from BBC
