Antarctica’s 180 trillion ton Pine Island glacier could collapse within 20 years as the floating ice shelf helping to hold it back is ‘ripping apart’, a study has warned.
The Pine Island ice shelf — located on the West Antarctic Ice Sheet — has been known to have been thinning now for decades as a result of climate change.
However, analysis of satellite images undertaken by researchers led from the University of Washington has shown a more dramatic loss in recent years.
From 2017 to 2020, large icebergs at the edge of the ice shelf have broken off into the Amundsen Sea, resulting in an acceleration of the glacier further inland.
The Pine Island Glacier is already responsible for a quarter of Antarctica’s ice loss — and its complete loss could see sea levels rise by some 1.6 feet (0.5 metres).
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Antarctica’s 180 trillion ton Pine Island glacier could collapse within 20 years as the floating ice shelf helping to hold it back is ‘ripping apart’. Pictured, a view across the ice showing the crevasses that form where the grounded glacier flows into the floating ice shelf
‘We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,’ said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory.
‘The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace.’
‘Things could be much more abrupt if we lose the rest of that ice shelf.’
Broadly speaking, the thinning of the Pine Island ice shelf over the last few decades has been caused by the presence of warmer ocean currents which have melting the underside of the floating ice mass.
Between the 1990s and 2019, this lead to an acceleration of the glacier behind the ice shelf, which went from moving at a rate of 1.5 miles (2.5 km) per year to 2.5 miles (4 km) on an annual basis — after which, however, its speed stabilised for a decade.
The recent changes, however, are being caused by a different process, Dr Joughin explained — one that is connected to the internal forces acting within the glacier.
‘The ice shelf appears to be ripping itself apart due to the glacier’s acceleration in the past decade or two,’ he added.
From 2017 to 2020, large icebergs at the edge of the ice shelf have broken off into the Amundsen Sea (as pictured in this time-lapse), resulting in an acceleration of the glacier inland
Between 2017 and 2020, the Pine Island ice shelf lost around a fifth of its area in series of dramatic breaks which were captured by the European Space Agency’s Copernicus Sentinel-1 satellites.
In their study, Dr Joughin and colleagues analysed images of the ice shelf taken between January 2015 and March 2020 — finding that the movement of two points on the glacier’s surface had sped up by 12 per cent between 2017–2020.
An ice flow model — developed at the University of Washington — confirmed that the loss of the ice shelf was responsive for the observed speedup.
‘The recent changes in speed are not due to melt-driven thinning — instead they’re due to the loss of the outer part of the ice shelf,’ Joughin said.
‘The glacier’s speedup is not catastrophic at this point. But if the rest of that ice shelf breaks up and goes away then this glacier could speed up quite a lot.’
Between 2017 and 2020, the Pine Island ice shelf lost around a fifth of its area in series of dramatic breaks which were captured by the Sentinel-1 satellites (a model of which is pictured)
‘Sediment records in front of and beneath the Pine Island ice shelf indicate that the glacier front has remained relatively stable over a few thousand years,’ explained paper author and ocean physicist Pierre Dutrieux of the British Antarctic Survey.
‘Regular advances and break-ups happened at approximately the same location until 2017 — and then successively worsened each year until 2020.’
‘The loss of Pine Island’s ice shelf now looks like it possibly could occur in the next decade or two, as opposed to the melt-driven subsurface change playing out over 100 or more years,’ he continued.
‘So it’s a potentially much more rapid and abrupt change.’
It is not exactly clear whether the ice shelf will continue to crumble, Dr Joughin added — with other factors, like the slope of the land below the glacier’s receding edge, having the potential to come into play as well.
The full findings of the study were published in the journal Science Advances.
The Pine Island Glacier is already responsible for a quarter of Antarctica’s ice loss — and its complete loss could see sea levels rise by some 1.6 feet (0.5 metres)
GLACIERS AND ICE SHEETS MELTING WOULD HAVE A ‘DRAMATIC IMPACT’ ON GLOBAL SEA LEVELS
Global sea levels could rise as much as 10ft (3 metres) if the Thwaites Glacier in West Antarctica collapses.
Sea level rises threaten cities from Shanghai to London, to low-lying swathes of Florida or Bangladesh, and to entire nations such as the Maldives.
In the UK, for instance, a rise of 6.7ft (2 metres) or more may cause areas such as Hull, Peterborough, Portsmouth and parts of east London and the Thames Estuary at risk of becoming submerged.
The collapse of the glacier, which could begin with decades, could also submerge major cities such as New York and Sydney.
Parts of New Orleans, Houston and Miami in the south on the US would also be particularly hard hit.
A 2014 study looked by the union of concerned scientists looked at 52 sea level indicators in communities across the US.
It found tidal flooding will dramatically increase in many East and Gulf Coast locations, based on a conservative estimate of predicted sea level increases based on current data.
The results showed that most of these communities will experience a steep increase in the number and severity of tidal flooding events over the coming decades.
By 2030, more than half of the 52 communities studied are projected to experience, on average, at least 24 tidal floods per year in exposed areas, assuming moderate sea level rise projections. Twenty of these communities could see a tripling or more in tidal flooding events.
The mid-Atlantic coast is expected to see some of the greatest increases in flood frequency. Places such as Annapolis, Maryland and Washington, DC can expect more than 150 tidal floods a year, and several locations in New Jersey could see 80 tidal floods or more.
In the UK, a two metre (6.5 ft) rise by 2040 would see large parts of Kent almost completely submerged, according to the results of a paper published in Proceedings of the National Academy of Science in November 2016.
Areas on the south coast like Portsmouth, as well as Cambridge and Peterborough would also be heavily affected.
Cities and towns around the Humber estuary, such as Hull, Scunthorpe and Grimsby would also experience intense flooding.