Climate crisis: Third of Antarctic ice shelf area ‘at risk of collapse’ if emissions aren’t rapidly reduced

The ice shelves which fringe Antarctica could be at major risk of collapse, potentially releasing “unimaginable” amounts of water into the ocean, if temperatures reach 4C above pre-industrial levels, research has warned.

The UN’s IPCC has already said that as current global heating trends continue and if emissions are not rapidly halted, then our planet is on course to see average temperature rises pushing towards 4C by the end of the century.

In this scenario, more than a third of the Antarctic’s ice shelf area could be at risk of collapsing into the sea, the researchers claim.

Scientists at the University of Reading said their study was the most detailed ever done in terms of forecasting how vulnerable the enormous floating platforms of ice surrounding Antarctica will become as the climate crisis worsens.

As temperatures rise they said we are likely to see “dramatic collapse events caused by melting and runoff”, which would have “unimaginable” impacts on sea level rise.

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Antarctica holds vast quantities of ice – around 90 per cent of all ice in the world.

Dr Ella Gilbert, a research scientist in the University of Reading’s Department of Meteorology, said: “Ice shelves are important buffers preventing glaciers on land from flowing freely into the ocean and contributing to sea level rise.

“When they collapse, it’s like a giant cork being removed from a bottle, allowing unimaginable amounts of water from glaciers to pour into the sea.

“We know that when melted ice accumulates on the surface of ice shelves, it can make them fracture and collapse spectacularly. Previous research has given us the bigger picture in terms of predicting Antarctic ice shelf decline, but our new study uses the latest modelling techniques to fill in the finer detail and provide more precise projections.”

She added: “The findings highlight the importance of limiting global temperature increases as set out in the Paris agreement if we are to avoid the worst consequences of climate change, including sea level rise.”

The research found that 34 per cent of the area of all Antarctic ice shelves – around half a million square kilometres – including 67 per cent of ice shelf area on the Antarctic Peninsula, would be at risk of destabilisation under 4C of warming.

However, the scientists said limiting temperature rise to 2C, as per the upper limit of the Paris agreement, rather than 4C, would halve the area at risk and potentially avoid “significant sea level rise”.

The researchers also identified Larsen C – the largest remaining ice shelf on the peninsula, which split to form the enormous A68 iceberg in 2017 – as one of four ice shelves that would be particularly threatened in a warmer climate.

The research team at Reading used state-of-the-art, high-resolution regional climate modelling to predict in more detail than before the impact of increased melting and water runoff on ice shelf stability.

Ice shelf vulnerability from this fracturing process was forecast under 1.5C, 2C and 4C global warming scenarios, which are all possible this century.

Every summer, ice at the surface of the ice shelf melts and trickles down into small air gaps in the snow layer below, where it refreezes.

However, in years when there is a lot of melting but little snowfall, the water pools on the surface or flows into crevasses, deepening and widening them until the ice shelf eventually fractures and collapses into the sea.

If there is water collecting on the surface of the ice shelf, the scientists said it could be vulnerable to collapse in this way.

This is what happened to the Larsen B ice shelf in 2002, which fractured following several years of warm summer temperatures. Its collapse caused the glaciers behind the ice shelf to speed up, losing billions of tonnes of ice to the sea.

The researchers identified the Larsen C, Shackleton, Pine Island and Wilkins ice shelves as most at-risk under 4C of warming, due to their geography and the significant runoff predicted in those areas.

Dr Gilbert said: “If temperatures continue to rise at current rates, we may lose more Antarctic ice shelves in the coming decades.

“Limiting warming will not just be good for Antarctica – preserving ice shelves means less global sea level rise, and that’s good for us all.”

Andrew Shepherd, Professor of Earth Observation at the University of Leeds, told The Independent: “Ice shelves have fringed Antarctica for thousands of years, and their collapse during our lifetime is an iconic example of climate change.

“This new study shows that melting at their surface is set to double with every 2C of global warming and spread southwards to parts of the continent where huge reservoirs of inland ice may lose their protective barrier.

“If that happens, we can expect rapid increases in sea level rise along every coastline of our planet.”

The research is published in the journal Geophysical Research Letters.