05/04/2021

Antarctic Glacier Will Reach Tipping Point

European Scientist - 
Pine Island Glacier in West Antarctica will reach a tipping point, leading to an irreversible and quick retreat with massive consequences for global sea level, according to a study published in the leading journal in this field, The Cryosphere.

Pine Island Glacier is a large fast-flowing ice stream draining an area of West Antarctica about two thirds the size of the UK. At the moment, it is the fastest melting glacier in Antarctica and accounts for a quarter of all ice lost in the region.

Satellite measurements have shown that Pine Island Glacier Basin contributes more water to the sea than any other basin in the world, and this is getting worse due to the recent acceleration of the ice stream.

It’s been the subject of debate for years whether this area of Antarctica could ever reach a tipping point in terms of ice melting and go over an irreversible point from which it would be impossible to recover.

Worryingly, if this were to happen, it could result in the collapse of the entire West Antarctic Ice sheet. This event alone could result in a rise of over three meters in the global sea level.

Now, researchers from Northumbria University, UK, have actually shown that this could be a harsh and brutal reality. Using an ice flow computer model created by the glaciology group, the researchers were able to predict and identify tipping points within the ice sheets.

“The potential for this region to cross a tipping point has been raised in the past, but our study is the first to confirm that Pine Island Glacier does indeed cross these critical thresholds”, said lead author Dr Sebastian Rosier, from Northumbria’s Department of Geography and Environmental Sciences.

“Many different computer simulations around the world are attempting to quantify how a changing climate could affect the West Antarctic Ice Sheet but identifying whether a period of retreat in these models is a tipping point is challenging.

Using this model, the team identified three distinct tipping points. The first and second are relatively small, but they still could lead to a considerable sea-level rise and would be difficult to recover. The third, however, would lead to a complete collapse of the Pine Island Glacier, potentially causing an increase of 1.2C in the water temperature.

For the researchers, changing wind patterns in the Amundsen Sea combined with long-term warming in the Circumpolar Deep Water could be enough to expose Pine Island Glacier to warmer water for long periods of time, making temperatures changes virtually inevitable.

“The possibility of Pine Island Glacier entering an unstable retreat has been raised before, but this is the first time that this possibility is rigorously established and quantified”, said Prof Hillary Gudmundsson, Professor of Glaciology and Extreme Environments.

The researcher is thrilled that this has finally been proven, but the findings are alarming. “Should the glacier enter unstable irreversible retreat, the impact on sea level could be measured in metres, and as this study shows, once the retreat starts, it might be impossible to halt it.”

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