Thwaites Glacier in West Antarctica is losing ice faster than earlier models indicated. A Nature Communications study published 12 October 2026 found that only models including a 2–5 kilometre-wide zone of seawater-driven melting could reproduce nearly 30 years of observed retreat, thinning and acceleration. Under the study’s assumptions, Thwaites could add up to 30 ± 6 millimetres to global mean sea level by 2100—about twice previous projections—even without additional warming. That is a higher near-term contribution, not a forecast that the entire glacier will suddenly collapse this century.
What is the Senegal-sized Antarctic glacier?
Thwaites Glacier is a major outlet of the marine-based West Antarctic Ice Sheet. Its drainage basin covers about 192,000 square kilometres (74,000 square miles), roughly the area of Senegal. International Thwaites Glacier Collaboration comparisons also describe the basin as approximately the size of Florida or Britain. The glacier is about 120 kilometres wide, and the ice is 800–1,200 metres deep near its grounding line, where it leaves the seabed and begins to float.
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Thwaites currently sends more than 50 billion tons of ice into the ocean each year and contributes about 4% of annual global sea-level rise, according to the National Snow and Ice Data Center’s International Thwaites Glacier Collaboration summary, accessed in 2026. Ice discharge from the region has nearly doubled over the past 30 years.
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What the 2026 study found
A wider melting zone matched observations
Mattia Poinelli and colleagues reported their findings in the paper Sea-level contribution from Thwaites Glacier doubles in an observation-constrained ice-sheet model in Nature Communications on 12 October 2026. Older-style simulations treated the grounding line as an almost razor-thin boundary. The new model represented a 2–5 kilometre-wide actively melting grounding zone, where seawater can move beneath ice that is still grounded.
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When that process was included, the model reproduced the retreat, thinning and speed-up observed over almost three decades. Forward runs allowed Thwaites to detach from stabilising seafloor ridges as early as 2038 in some scenarios. Those dates describe model outcomes under specified assumptions; they are not a timetable for total collapse.
Projected sea-level contribution
| Model treatment or outcome | What it indicates |
|---|---|
| Sharp grounding-line treatment used in earlier projections | Produced lower 2100 contributions than the new observation-constrained runs |
| 2–5 km active grounding zone | Reproduced observed retreat, thinning and acceleration |
| New forward simulations | Up to 30 ± 6 mm of global mean sea-level rise by 2100, without additional warming; Poinelli et al., Nature Communications, 2026 |
| Ridge detachment | Permitted as early as 2038 in some model runs |
The 30 ± 6 mm figure is a modelled range, not a measurement of future sea level. “Up to” and the uncertainty interval matter: actual change depends on ocean conditions, atmospheric warming, ice dynamics and future emissions.
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Why a grounding zone can accelerate melting
Tides expose more ice to warm water
The grounding line marks the transition from ice resting on bedrock to an ice shelf floating on seawater. In reality, that transition can span several kilometres. Tides lift and lower the ice, allowing seawater to intrude beneath portions that would be treated as grounded in a simpler model.
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →The water can then reach more of the ice base and increase basal melt. Lead author Mattia Poinelli told an Al Jazeera explainer published 17 October 2026 that tidal pumping allows warm water to reach “deep underneath the ice sheets and causing vigorous melting.” This mechanism removes ice that helps anchor the glacier and can make retreat faster when the bed slopes inland.
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What would a complete Thwaites collapse mean?
About 65 centimetres, but over centuries
The International Thwaites Glacier Collaboration estimates that complete loss of Thwaites contains enough ice to raise global sea level by about 65 centimetres, based on BedMachine studies. That is the glacier’s eventual sea-level equivalent, not a 2100 forecast. ITGC material says a complete collapse would take centuries.
The new study therefore changes the expected rate of near-term contribution rather than predicting an imminent disappearance. British Antarctic Survey modelling indicates that Thwaites continues losing ice for at least 150 years even under extreme ocean-cooling scenarios. With today’s relatively warm ocean and continued greenhouse-gas emissions, the trajectory is worse. ITGC expects retreat to continue through the 21st and 22nd centuries, while the exact timing of a broader collapse remains uncertain.
What “Doomsday Glacier” does—and does not—mean
“Doomsday Glacier” is a media nickname, not a scientific deadline. The term reflects Thwaites’ size, its role in West Antarctic ice flow and the consequences of losing its buttressing effect. It does not mean that the glacier is expected to vanish suddenly or cause an immediate global catastrophe.
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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →An Al Jazeera account of the 2026 study reported a 60% chance that Thwaites could unpin from the Mouginot Ridge by the end of this century. That probability belongs to the report’s description of the study’s results and should not be read as an unconditional prediction of total collapse.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why one glacier matters to coastal cities
Global mean sea-level rise accumulates. Every additional millimetre raises the starting point for high tides, storm surges and coastal flooding. A faster contribution from Thwaites can therefore increase risks for ports, housing, drainage systems, roads and freshwater supplies long before a complete ice-sheet collapse.
Thwaites also acts as a buttress for inland ice. As its floating ice and grounded supports retreat, ice farther inland can flow more rapidly toward the ocean. A wider West Antarctic Ice Sheet response would add more sea-level rise than Thwaites alone and would persist for centuries. The ITGC’s 2025 findings say broader West Antarctic collapse over coming centuries cannot be ruled out and would affect coastal communities worldwide.
What can still change the outcome?
Emissions cuts affect the rate of loss
The International Thwaites Glacier Collaboration’s September 2025 findings state: “Immediate and sustained climate change mitigation (decarbonisation) offers the best hope of delaying this ice loss and avoiding initiation of similar unstable retreat in marine-based sectors of East Antarctica.” Cutting greenhouse-gas emissions cannot reverse all committed sea-level rise, but it can reduce ocean warming and delay further retreat.
Adaptation must proceed alongside mitigation
Because some sea-level rise is unavoidable, coastal planning needs updated elevation data, flood maps, building standards, drainage capacity and managed-retreat options where protection is not practical. The relevant planning horizon is decades to centuries: decisions made for infrastructure with long lifetimes must account for continued rise even if emissions fall sharply.
The practical bottom line
Thwaites is melting faster than older models suggested because seawater penetrates a broad, tidally pumped grounding zone beneath the glacier. The best current estimate from the 2026 study is up to 30 ± 6 millimetres of global mean sea-level rise by 2100 under its stated assumptions. Complete collapse would eventually contribute about 65 centimetres, but would unfold over centuries. The immediate policy response is two-track: cut emissions to slow the loss and prepare coastal communities for additional sea-level rise that can no longer be avoided.
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