The 180 trillion-ton Pine Island glacier in Antarctica could collapse within 20 years if the floating ice shelf holding it back “ruptures,” a study has warned.
Pine Island’s ice shelf – located on the West Antarctic Ice Sheet – has been known to thin for decades as a result of climate change.
However, satellite image analysis conducted by researchers led by the University of Washington has shown a more dramatic loss in recent years.
From 2017 to 2020, large icebergs on the edge of the ice shelf broke off in the Amundsen Sea, causing the glacier to accelerate further inland.
The Pine Island Glacier is already responsible for a quarter of Antarctica’s ice loss — and the complete loss could cause sea levels to rise by about 0.5 meters.
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Antarctica’s 180 trillion-ton Pine Island Glacier could collapse within 20 years if the floating ice shelf holding it back “ruptures.” Pictured, a view over the ice showing the fissures 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 faster than expected,” said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory.
“The processes we studied in this region led to an irreversible collapse, but at a fairly measured pace.”
“It could be much more abrupt if we lose the rest of that ice shelf.”
Broadly speaking, the thinning of the Pine Island Ice Shelf in recent decades has been caused by the presence of warmer ocean currents that have melted the bottom of the floating ice mass.
Between the 1990s and 2019, this led to an acceleration of the glacier behind the ice shelf, going from moving 2.5 miles (2.5 km) per year to 2.5 miles (4 km) on an annual basis – after which, however, the rate stabilized for a decade.
However, the recent changes are caused by a different process, Dr Joughin explained — a process related to the internal forces acting in the glacier.
“The ice shelf appears to be tearing itself apart as a result of the glacier’s acceleration over the past decade or two,” he added.
From 2017 to 2020, large icebergs on the edge of the ice shelf broke off in the Amundsen Sea (as depicted in this time-lapse), resulting in an acceleration of the glacier inland
Between 2017 and 2020, the Pine Island Ice Shelf lost about a fifth of its surface in series of dramatic breaks captured by the European Space Agency’s Copernicus Sentinel-1 satellites.
In their study, Dr. Joughin and colleagues analyzed images of the ice shelf taken between January 2015 and March 2020. They found that the movement of two points on the glacier’s surface had accelerated by 12 percent between 2017-2020.
An ice flow model – developed at the University of Washington – confirmed that the ice shelf loss responded to the observed acceleration.
“The recent speed changes are not due to melt-driven thinning — instead, they are due to the loss of the outermost portion of the ice shelf,” Joughin said.
“The acceleration of the glacier is not catastrophic at the moment. But if the rest of that ice shelf breaks and disappears, this glacier could accelerate considerably.’
Between 2017 and 2020, the Pine Island Ice Shelf lost about a fifth of its area in series of dramatic breaks captured by the Sentinel-1 satellites (a model of which is pictured)
“Sediment data in front of and under the Pine Island ice shelf indicate that the glacier front has remained relatively stable over the course of a few thousand years,” explains author and ocean physicist Pierre Dutrieux of the British Antarctic Survey.
“Regular advances and breaks occurred in roughly the same location until 2017 – then worsened every year until 2020.”
“The loss of the Pine Island ice shelf now looks like it could happen in the next decade, as opposed to the melt-induced subsurface change that will take more than 100 years or more,” he continued. .
“So it’s a potentially much faster and more abrupt change.”
It’s not exactly clear whether the ice shelf will continue to crumble, Dr Joughin added — with other factors, such as the slope of the land beneath the glacier’s receding edge, having the potential to play a role as well.
The study’s full findings were published in the journal scientific progress.
The Pine Island Glacier is already responsible for a quarter of Antarctica’s ice loss – and the complete loss could cause sea levels to rise by about 0.5 meters
GLACIER AND ICE SHEET MELTING WOULD HAVE A ‘DRAMATIC IMPACT’ ON GLOBAL SEASIDES
If the Thwaites Glacier in West Antarctica collapses, sea levels could rise by up to 3 meters worldwide.
Sea level rise threatens cities from Shanghai to London, to low-lying parts of Florida or Bangladesh, and to entire nations like the Maldives.
In the UK, for example, a rise of 2 meters or more could flood areas such as Hull, Peterborough, Portsmouth and parts of East London and the Thames Estuary.
The glacier’s collapse, which could start with decades, could also flood major cities like New York and Sydney.
Parts of New Orleans, Houston and Miami in the southern US would also be particularly hard hit.
A 2014 study conducted by the Union of Concerned Scientists looked at 52 sea level indicators in communities across the US.
Based on a conservative estimate of the predicted sea level rise based on current data, it has been determined that the tide will increase dramatically in many locations on the eastern and gulf coasts.
The results showed that most of these communities will experience a sharp increase in the number and severity of tidal flooding in the coming decades.
By 2030, more than half of the 52 communities surveyed are expected to experience an average of at least 24 tidal floods per year in exposed areas, assuming moderate sea level rise. Twenty of these communities could see a tripling or more in tidal flooding.
The mid-Atlantic coast is expected to see some of the largest increases in flood frequency. Places such as Annapolis, Maryland and Washington DC can expect more than 150 tidal floods per year, and 80 or more tidal floods can occur in several locations in New Jersey.
In the UK, a two-metre (6.5 ft) rise would almost completely submerge large parts of Kent by 2040, according to the results of a paper published in Proceedings of the National Academy of Science in November 2016.
Areas on the south coast such as Portsmouth, as well as Cambridge and Peterborough would also be hit hard.
Towns and villages around the Humber Estuary, such as Hull, Scunthorpe and Grimsby, would also experience severe flooding.