Scientists warn Antarctic ice has thinned by ‘extraordinary amounts’

Nearly a quarter of West Antarctica’s ice is now considered unstable after unprecedented thinning across its largest glaciers over the last two decades.

Scientists analyzing more than 800 million measurements collected by an array of satellites since 1992 have found the Pine Island and Thwaite’s Glaciers are now losing ice at a rate five times faster than they were when the survey began.

In areas hit hardest, researchers found the ice has thinned by as much as 122 meters (400 feet), causing the affected glaciers to become unstable.

The findings add to the ongoing concern over sea level rise resulting from glacier loss and the implications it has for coastal cities.  

The alarming new study published in the journal Geophysical Research Letters found that thinning has now spread to 24 percent of West Antarctica, including the majority of its largest ice streams.

These areas are losing more mass through melting and ice calving events than they’re gaining through snowfall, the researchers say.

‘In parts of Antarctica the ice sheet has thinned by extraordinary amounts, and so we set out to show how much was due to changes in climate and how much was due to weather,’ said lead author Andy Shepherd.

The team used ice sheet heights recorded by the ERS-1, ERS-2, Envisat, and CryoSat-2 satellite altimeter missions between 1992 and 2017, along with snowfall simulations from the RACMO regional climate model.

This allowed them to differentiate between changes linked to short-lived weather patterns and those stemming from longer-term phenomena, such as increasing ocean temperature.

While fluctuations in snowfall did give rise to small changes in height over some areas, the effects only lasted for a few years at a time.

Dramatic changes in ice thickness, on the other hand, highlight worsening instability over decades.

The team estimates 24 percent of West Antarctica is now unstable. 

‘Knowing how much snow has fallen has really helped us to detect the underlying change in glacier ice within the satellite record,’ Shepherd said.

‘We can see clearly now that a wave of thinning has spread rapidly across some of Antarctica’s most vulnerable glaciers, and their losses are driving up sea levels around the planet.

‘Altogether, ice losses from East and West Antarctica have contributed 4.6 mm to global sea level rise since 1992.’

The research relied on 25 years of measurements from ESA satellites, which the team says is critical in understanding these long-term patterns.

‘This is an important demonstration of how satellite missions can help us to understand how our planet is changing,’ says co-author Dr Marcus Engdahl of the European Space Agency.

‘The polar regions are hostile environments and are extremely difficult to access from the ground. Because of this, the view from space is an essential tool for tracking the effects of climate change.’

 

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