The mighty Pine Island Glacier, the largest single contributor to sea level rise in Antarctica, has probably begun an irreversible retreat, scientists have warned.
Published in the journal, Nature Climate Change, the researchers’ work shows that even if the region were to experience much colder conditions, the retreat could continue.
The Pine Island Glacier currently contributes 25% of the total ice loss from West Antarctica.
The team of scientists examined three computer models as well as field observations to study how the glacier’s ice flows and how this could change over coming decades.
All the models show the glacier has become unstable and that it will continue to retreat for tens of kilometres.
This process could see the amount of water the glacier is adding to the ocean increase five fold – contributing to sea level rise on the order of between 3.5mm-10mm in the next 20 years.
“You can think of PIG like a ball. It’s been kicked and it’s just going to keep on rolling for the foreseeable future,” said Dr Hilmar Gudmundsson from the British Antarctic Survey (BAS).
Pine Island Glacier is a colossal feature. Covering more than 160,000 sq km (two-thirds the size of the UK), it drains something like 20% of all the ice flowing off the west of the White Continent.
Satellite and airborne measurements have recorded a marked thinning and a surge in velocity in recent decades.
Its grounding line – the zone where the glacier enters the sea and lifts up and floats – has reversed tens of km over the same period.
Much of this behaviour is driven not by higher air temperatures in the cold south but by warm ocean bottom-waters getting under and eroding the floating ice shelf at the head of the glacier.
Key to Pine Island Glacier’s observed behaviour is that a large section of it sits below sea level, with the rock bed sloping back towards the continent.
The very latest satellite data details the thinning occurring in this region of West Antarctica.
This can produce what scientists refer to as a “marine ice sheet instability” – an inherently unstable architecture, which, once knocked, can go into an irreversible decline.
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