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Summary
Antarctica is almost twice the size of Australia and contains 90% of the world’s freshwater. It it all melted it would add ~60-70m to sea levels. 125,000 years ago when temperatures and CO2 levels were similar to that of today, sea levels were ~6-10 metres higher. Today, Antarctica’s ice loss is now locked in.
Over the past 50 years, the west coast of the Antarctic Peninsula (Figs. 2 & 3) has been one of the fastest warming parts of the planet, with air temperatures 3-5 times higher than the average rate of global warming due to polar amplification.
The East Antarctic Ice Sheet (EAIS)(Figs. 2 & 3) is not as stable as previously thought and is contributing to rising sea levels. Temperatures there reached 38.5°C above normal in 2022, a new world record for the largest temperature excess ever measured at an established weather station.
There is now broad scientific agreement that the basin has the potential to change under future warming, but we still don’t know how quickly change could occur, what climate thresholds may trigger large-scale retreat, and how much the basin may ultimately contribute to future sea-level rise – Prof. Nancy Bertler, climate scientist Earth Sciences New Zealand Sept. 2026
The Western Antarctic Ice Sheet (WAIS) covers islands and land below sea level (Figs. 2-4). This makes it particularly vulnerable to collapse. The Thwaites Glacier is currently of greatest concern. Increasingly warmer ocean water is melting it from below, undercutting it so that it’s collapsing. Nicknamed the ‘Doomsday Glacier’, it acts like a plug, holding back the WAIS ice sheet. In 2026, the eastern ice shelf of the Thwaites Glacier began falling apart.
“Suddenly, large areas are just falling to pieces,” says Christian Wild, from the University of Innsbruck in Austria. “It looks like a windscreen that’s shattering… It’s essentially in free fall now,” Wild added, noting the pace has quickened further over the past five months. – GBN News May 2026
Implications
A first threshold, potentially as low as 1–2 °C above pre-industrial levels, triggers the long-term collapse of ~40% of marine ice volume in West Antarctica. Marine-based sectors in East Antarctica, representing ~5 m of potential sea-level rise, are at risk of losing stability at 2–5 °C. – Winkelmann et al 2026
In 2024 and 2026 average global temperatures exceeded 1.5°C above pre-industrial levels.
Glossary of terms
- Ice sheet: continental glaciers that have joined together to cover the surrounding land in an area greater than 50,000 km². There are only three in the world: Greenland and two in Antarctica: the West Antarctic Ice Sheet (WAIS) the East Antarctic Ice Sheet (EAIS). The existence of these ice sheets are why we are still in an ice age. When an ice sheet spreads out from the coast and moves over the ocean water, the floating portion becomes an ice shelf.
- Ice shelf: a tidewater (coastal) that part of a glacier or ice sheet that flows down to a coastline and onto the ocean surface, where it floats (Map 1). Thwaites (Map 2) and Pine Island are outlet glaciers with ice shelves; the eastern section of Thwaites ice shelf is now breaking up (May 2026).
- Marine ice sheet: an ice sheet with its base on ground that’s below sea level. This makes it particularly vulnerable to undercutting by warming waters. Much of the WAIS is a marine ice shelf.
- Grounding line: the point where the bottom or ‘basal’ (bottom) side of a glacier leaves land and extends out over the ocean (Processes | Fig. 1).
- Outlet glacier: drains inland glaciers/ice sheets through gaps in the surrounding topography. If an outlet glacier reaches the coast (some terminate inland) the front section may become an ice sheet (Fig. 7).
Processes: how ice sheet melt and collapse
- If the grounding line is below sea level, the glacier is prone to undercutting by increasingly warmer ocean waters.
- If land slopes down inland instead of rising upwards, warm ocean currents water flow further beneath the glacier, eroding it and further destabilising it. Thwaites Glacier, now considered the most unstable is grounded below sea level, and much of the the land behind the grounding line slopes down.
The Jakobshavns Effect is a group of positive feedback mechanisms which allow Jakobshavns Glacier to literally pull ice out of the Greenland Ice Sheet at a rate exceeding 7 km/a across a floating terminus 800 m thick and 6 km wide. The pulling power results from an imbalance of horizontal hydrostatic forces in ice and water columns at the grounding line of the floating terminus.…A small imbalance of forces caused by some perturbation can cause a substantial non-linear response. – Prof. Terry Hughes ‘The Jakobshavns Effect’
Or as Prof. Jason Box puts it:
There are too many variables that determine exactly when a glacier calves. A single cracking event could conceivably be triggered by a seagull, acting like the straw that broke the camel’s back.
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The ice is normally stabilized by sitting on the seafloor. As warm ocean currents eat away at the base, the ice thins, lifts away from the seafloor and breaks, losing its ability to act as a brake on the flow of ice from the continent. Click the image for the interactive webpage.
When this happens on marine glaciers or ice shelves once the water reaches the base of the ice, the ice shelf is effectively turned into Swiss cheese and rapidly breaks up.
Whereas when this happens to glaciers sitting on land the outcome is different. If the glacier is on land that slopes downhill inland, when the meltwater reaches the bottom of the glacier, it lifts the glacier and/or joins with ocean water that has reached this point, adding to the melting and undercutting from below.
Where the glacier is on land that slopes downhill towards the ocean, the meltwater lubricates the glacier like a water slide, making it flow faster, which in turn opens or widens more crevasses, allowing yet more meltwater lakes to drain, and so on in a feedback effect. When this warm buoyant freshwater reaches the submerged terminus (front) of the glacier, it scours it from below, then shoots hundreds of metres up the terminus. In some instances it erupts at the surface in a churning jaccuzi-like swirl of mud and ice.
West Antarctic Ice Shelf (WAIS) ‘A disaster waiting to happen’
Brief history of trying to predict what could—and now is—happening 1968-2026
1968: glaciologist John Mercer voiced concerns that the West Antarctic Ice Shelf (WAIS) could abruptly collapse, leading to a rapid rise in sea levels because the WAIS contains enough ice to add 3.3m to global sea levels:
A disquieting thought is that if the present highly simplified climatic models are even approximately correct, this deglaciation (of the WAIS) may be part of the price that must be paid in order to buy enough time for industrial civilisation to make the changeover from fossil fuels to other sources of energy. – ‘Antarctic Ice and Sangamon Sea Level’, International Association of Scientific Hydrology Symposium 79, pp217–225, 1968 (PDF)
1978: In spite of the geological evidence that past climate change has led to abrupt sea level rise, the notion that a few degrees of warming could have any impact on the coldest place on Earth was largely dismissed:
Mercer’s views, first buried in a publication of the International Association of Scientific Hydrology, caught the attention of policy makers when published in 1978 in Nature under the title ‘West Antarctic ice sheet and CO2 greenhouse effect: A threat of disaster’ … By the late 1980s the notion that loss of ice shelves could lead to disintegration of the entire ice sheet fell out of favour. – Oppenheimer, 2004.
1995: Larsen A Ice Shelf on the Antarctic Peninsular (northern tip of WAIS)—one of the fastest warming areas on the planet—broke apart.
2002: Its neighbour, the Larsen B Ice Shelf, disintegrated in spectacular fashion in just six weeks, not hundreds of years as previously assumed (Video 4):
It was sitting there stable for 10,000 years and then it was just…gone. – Dr. Jeremy Bassis.
2008:
We see things today that five years ago would have seemed completely impossible, extravagant, exaggerated. – Eric Rignot, JPL/NASA in The big thaw, National Geographic
2009:
In spite of observations and the growing evidence that similar dramatic ‘non-linear’ abrupt changes to glaciers were being seen in Greenland, the 2009 IPCC 4th Assessment Report stated that sea levels were not likely to be greatly affected by melting glaciers, either from Antarctica or anywhere on Earth, in the twenty-first century. Indeed, the report stated that the continent was ‘too cold for widespread surface melting and is expected to gain in mass due to increased snowfall.’
Meanwhile Pine Island Glacier the fastest melting glacier in Antarctica that drains about 10% of the WAIS, was already thinning and accelerating.
2017: A section of Larsen C broke off as a single 5,800 km2 iceberg. The scientific scramble to understand these events, which failed to be predicted by the climate models, had in fact been underway since 1986, with similar abrupt collapses being seen in Greenland.
2018: Massive chunks broke off Pine Island Glacier (Video 5). Then more broke off in 2020.
Using genetic analyses of a type of circum-Antarctic octopus, Pareledone turqueti, Lau et al., showed that the WAIS collapsed completely during the last interglacial period, when global sea levels were 5 to 10 meters higher than today and global average temperatures were only about 1°C warmer. – Science Editorial 2023
Satellite data show that seawater is being flushed beneath the grounding zone of Thwaites Glacier by the tides, perhaps as far as 12 km, triggering vigorous melting. As ocean temperatures increase, this tidal pumping mechanism may lead to runaway melting under many areas of the Antarctic Ice Sheet. This recently-highlighted process could potentially double sea-level rise from Antarctica.
Current models used to generate global projections of sea-level rise, such as those that informed the last IPCC report (2022), do not adequately represent this process, meaning that future sea-level rise from Antarctica may be substantially underestimated. – UNESCO State of the Cryosphere 2024
“Suddenly, large areas are just falling to pieces,” says Christian Wild, from the University of Innsbruck in Austria. “It looks like a windscreen that’s shattering….It’s essentially in free fall now,” Wild added, noting the pace has quickened further over the past five months – New Scientists 18 May 2026
The ice shelf that buttresses it has undergone significant change in the last decade, resulting in a 20% increase in ice velocity. – Wells-Moran et al, PNAS 11 August 2026
East Antarctic Ice Sheet (EAIS): not as stable as once thought
About 400,000 years ago…the global temperature was 1 to 2 degrees Celsius greater. Data indicate[s] that the ice sheet margin at the Wilkes Basin (EAIS) retreated to about 700 kilometres inland from the current position, which—assuming current ice volumes—would have contributed about 3 to 4 metres to global sea levels. – Blackburn et al, July 2020
Until a few years ago, the East Antarctic Ice Sheet (EAIS), which contains enough ice to raise global sea levels ~54m if it all melted, was considered relatively stable. This was in part due to the bulk of the icecap sitting on land rather than the seabed (Map 2). However, measurements using satellite records from 1979 to 2017 show that the EIAS had contributed about 30% to rising sea levels during this period, in part because as the climate warmed, stronger polar westerly winds were pushing more of the warmer circumpolar deep water current toward outlet glaciers, undercutting them (Fig. 1 and Video 9). In 2022, this led to the abrupt collapse of the Conger Ice Shelf (Video 10)
These outlet glaciers with ice shelves behave in the same way as the WAIS outlet glaciers, however they hold back the far larger EAIS.
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Prof. Matt King, Director of the Australian Centre for Excellence in Antarctic Science (ACEAS) outlines the changes and surprises emerging from East Antarctica and the massive reduction in the Antarctic Circumpolar Current.
The loss of the Conger–Glenzer ice shelf in 2022 was the culmination of a multidecadal process of disintegration, signalling East Antarctica may not be as stable as we once thought. – Walker et al, 2024
Back in 2017, other researchers found more than 65,000 meltwater lakes on the EAIS. While most lakes were found on outlet glaciers, thousands were seen up to 50km inland on the ice sheet, and as high as 1500m altitude (Figs. 4 & 5). For inland and high altitude lakes to form, surface temperatures need to be well above freezing, and for sustained periods.
For reasons explained in Video 9, these may not play as large a role as the warm deep waters along the WAIS, but they are also being seen on the southern coasts of the EIS (Fig. 4a), which is also vulnerable to warm deep waters, leading to ‘bottom up’ melting.
Recently, relatively warm waters that are normally found offshore are coming onto the Antarctic continental shelves, threatening the stability of East Antarctic ice shelves. – Ribeiro et al, 2023
Totten Glacier hosts the most rapidly thinning ice in East Antarctica. This record of thinning is due to rapid melt along the grounding line of the Totten Ice Shelf (TIS), where warm ocean water from the open ocean flows into ice shelf cavities… – Nakayama et al 2023
Meltwater on the ice shelf next to McMurdo Station. Credit: Nicholas Bayou, UNAVCO
Fig. 7 Outlet glacier Antarctica image: Sonny Whitelaw
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