Hotter Antarctic summers posing increasing threat to stability of world’s largest ice sheet, satellite observations show

The East Antarctic ice sheet is the biggest land-based piece of frozen water on the planet. It holds about 80 per cent of all ice in the world, stretching up to 4,800 metres in thickness in some places, and containing enough water to raise global sea levels by 52 metres.

Humans are generally keen for it to stay in place.

But new research shows that warmer summers due to the worsening climate crisis are seriously threatening the floating ice shelves which fringe the ice sheet, helping hold it in place.

The study, led by a team at Durham University, examined supraglacial lakes – made up of surface meltwater – around the East Antarctic ice sheet, using thousands of satellite images to determine the lakes’ size and volume between 2014 and 2020.

It found the lakes’ volume could vary year-to-year by as much as 200 per cent on individual ice shelves, and by around 72 per cent overall – across ice shelves and the ice sheet.

The researchers said these lakes were also found to be deeper and larger in warmer melt seasons and formed on some potentially vulnerable ice shelves.

This will help scientists assess which ice shelves may be most at risk of breaking up as a consequence of surface melting, the team said.

Lead researcher, PhD student Jennifer Arthur, from Durham University’s department of geography, said: “We knew that supraglacial lakes were more extensive than previously thought around the East Antarctic ice sheet, but until now only had snapshots of these in some years.

“Our study reveals these lakes change in scale far more than we originally suspected. We were surprised at how much lakes can change year-to-year between ice shelves.

“We explored the potential reasons for this and found that warmer summer air temperatures in Antarctica correlated with more extensive lakes."

She added: “Due to climate change, air temperatures in Antarctica will continue to rise and our study suggests that this will lead to an increase in the number and volume of supraglacial lakes, which will in turn put some East Antarctic ice shelves at risk of meltwater-driven collapse.”

The findings come amid heightened concern about how the climate crisis is impacting Antarctica, after record temperatures up to 40C above average were recorded this month.

The continent also saw record low levels of sea ice, which helped the expedition to locate Ernest Shackleton’s lost ship Endurance, which sank during his 1915 expedition to cross Antarctica.

The loss of ice shelves fringing an ice sheet allows the ice which is further inland to then flow faster into the ocean, contributing to global sea-level rise.

The team said that until now, observations of supraglacial lakes on the East Antarctica ice sheet were relatively scarce and the year-to-year variability was largely unknown, making it difficult to assess whether some ice shelves are close to meltwater-driven break up due to the climate crisis.

The research is published in the journal Nature Communications.