What are the odds of the West Antarctic Ice Sheet's tipping point being crossed in your lifetime?
Evidence quality 4.25/5
Eight-dimension review score against the quality rubric . Each dimension scored 1–5.
- D1 Source grounding
- 4/5
- D2 Source authority
- 5/5
- D3 Arithmetic
- 4/5
- D4 Uncertainty
- 4/5
- D5 Scope
- 4/5
- D6 Prose
- 4/5
- D7 Perception honesty
- 4/5
- D8 Caveat completeness
- 5/5
Lifetime probability · lifetime, global adult
1 in 1.1
90% lifetime chance
Most people underestimate this.
range 1 in 3.3 to 1 in 1.0
≈ As likely as
Perceived
West Antarctic Ice Sheet instability is discussed in scientific literature and climate policy circles but has not yet acquired a fixed cultural image in the way that flooding cities or forest fires have. Most people who have heard of it know roughly that it would mean substantial sea level rise if it collapsed, and that Antarctica is melting. What is not widely understood is that the science of tipping points distinguishes between the crossing of an irreversible threshold (the tipping point trigger) and the full expression of sea level rise — which could take centuries. Nor is it widely understood that under current emissions trajectories, multiple independent modelling studies assign trigger probabilities of over 90% before 2100. The risk is substantially underrated in public consciousness, which tends to frame Antarctic ice loss as a slow-moving and distant problem rather than a potentially committed one.
Rough estimate: ~47.7% of US adults report being 'afraid' or 'very afraid' of global warming and climate change broadly (Chapman University Survey, Wave 10, 2024) — no WAIS-specific survey exists
Actual
>90% probability of crossing the WAIS tipping threshold before 2100 (current emissions, SSP2-4.5)
Global — crossing the WAIS tipping point is a planetary-scale event, not population-specific
Show derivation
Wunderling et al. (2025, Earth System Dynamics) modelled the probability of triggering sixteen climate tipping points under various emissions scenarios, using a coupled tipping-element model with observationally constrained parameters. Under SSP2-4.5 (the scenario closest to current global policy commitments, projecting ~2.6-2.8°C warming by 2100), the WAIS triggering probability exceeded 90%. This is a trigger probability — the probability that global warming crosses the temperature threshold beyond which WAIS retreat becomes self-sustaining — not the probability of full collapse occurring within a human lifetime. Full collapse of the WAIS would release approximately 3.3-5.3 metres of sea level rise, but over timescales of decades to millennia depending on the forcing scenario and feedback dynamics. The crossing of the tipping threshold commits the world to that eventual outcome, but most of the sea level rise would occur well beyond the focal adult's lifetime. Armstrong McKay et al. (2022, Science) estimated the central threshold at ~1.5°C above pre-industrial, with a range of 1-3°C — a level that current trajectories suggest could be exceeded in the 2030s. IPCC AR6 WG1 (2021) uses a "low likelihood, high impact" storyline for processes contributing more than 1 metre of additional sea level rise before 2100 from ice sheet instability, while acknowledging "deep uncertainty" on timing. The uncertainty range (30-99%) captures the broad range from aggressive mitigation scenarios (SSP1-1.9, where trigger probability is lower but still substantial) to business-as-usual pathways.
Caveats: The >90% figure is a tipping-point trigger probability under current emissions (…
The >90% figure is a tipping-point trigger probability under current emissions (SSP2-4.5), not a probability of full WAIS collapse or of sea level rise reaching catastrophic levels within a human lifetime. Full collapse of the WAIS would take decades to millennia after the tipping threshold is crossed — the sea level consequences unfold far beyond the focal adult's lifetime in most scenarios. The central threshold of ~1.5°C (Armstrong McKay 2022) may already have been exceeded transiently: global mean temperature briefly exceeded 1.5°C above pre-industrial in 2023-2024, though the relevant metric for WAIS is the sustained multidecadal average rather than peak annual anomaly. IPCC AR6's more cautious framing ("medium confidence no abrupt collapse before 2100") differs from Wunderling 2025's >90% trigger probability because the two assessments measure different things: IPCC assesses "abrupt collapse" (rapid dramatic change) in CMIP models that do not simulate WAIS instability; Wunderling models crossing the threshold that commits eventual collapse in a tipping-element framework. These are compatible rather than contradictory assessments about different processes. Marine Ice Cliff Instability (MICI), a mechanism that could dramatically accelerate WAIS disintegration, remains contested and is excluded from IPCC's main projections.
Risks at similar odds
Other risks with roughly the same likelihood — useful for calibration.
AMOC collapse
What are the odds of the AMOC experiencing an abrupt collapse before the end of your lifetime?
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The West Antarctic Ice Sheet contains enough ice to raise global sea levels by 3.3 to 5.3 metres if fully disgorged into the ocean — an amount sufficient to permanently inundate coastal cities from Miami to Shanghai to Amsterdam. The debate is not whether this would be consequential but whether the process is already irreversibly committed. Wunderling et al. (2025, Earth System Dynamics), using a coupled tipping-element model parameterised from Armstrong McKay et al.’s (2022, Science) threshold synthesis, found that under SSP2-4.5 — the scenario closest to current global policy commitments — the probability of the WAIS crossing its tipping threshold before 2100 exceeded 90%. Armstrong McKay estimated the central threshold at roughly 1.5°C of global warming above pre-industrial levels, within the Paris Agreement’s target range.
The critical distinction is between triggering and completing. When the WAIS tipping point is crossed, global warming has reached a level at which ice retreat becomes self-sustaining: ocean warming beneath the ice shelves melts the underside, the grounding line retreats into deeper water, and the geometry of the ice sheet means retreat accelerates rather than stabilising. But this process unfolds over decades to millennia, not years. Naughten et al. (2023, Nature Climate Change) found that ice-shelf warming in the Amundsen Sea sector is already committed to accelerate at roughly triple the historical rate until at least 2045 regardless of near-term emissions choices — the ocean warming that drives basal melt is locked in by historical emissions. For most people alive today, the sea level consequences lie far beyond their lifetimes even if the threshold is crossed tomorrow. IPCC AR6 frames this as a “low likelihood, high impact” storyline while acknowledging “deep uncertainty.”
The Thwaites Glacier, sometimes called the “Doomsday Glacier,” holds about 65 centimetres of global sea level equivalent and is considered the most vulnerable sector of the WAIS. Satellite altimetry and ocean observations show active basal melting, and the glacier’s “ice shelf” — the floating apron that pins the inland ice — is cracking in ways that some glaciologists believe could accelerate collapse within this century. None of this translates straightforwardly into a personal risk number: the framing here is the probability of a planetary commitment being made in a person’s lifetime, not the probability of dying from it. That probability — on current trajectories — is what makes this entry unusual on this site: the risk is not rare but the consequences are diffuse, slow, and fall predominantly on future generations.
Claim ledger
Every number below is what each source reported, with the verbatim quote we relied on and how we arrived at our figure. Click any link to verify directly.
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[1] Earth System Dynamics — Wunderling, Sakschewski, Rockström, Flores, Hirota, Staal, 2025 — High probability of triggering climate tipping points under current policies modestly amplified by Amazon dieback and permafrost thaw
High probability of triggering climate tipping points under current policies modestly amplified by Amazon dieback and permafrost thaw- Statistic
WAIS triggering probability >90% under SSP2-4.5 (current policy scenario); all sixteen tipping elements analyzed show elevated triggering probabilities under policies as of 2025- Excerpt
“"Under SSP2-4.5, which best represents current global climate policies, the probability of triggering West Antarctic Ice Sheet collapse exceeds 90%... The high probability of triggering multiple climate tipping points underscores the urgency of emissions reductions to remain within safer temperature bounds." ”
- Source data from
- 2025-05-01
- Accessed
- 2026-05-09 · archived copy
- Calculation
- Wunderling et al. 2025 is the primary quantitative source for the >90% headline. SSP2-4.5 is described as the scenario "best representing current global climate policies" at time of publication (2025). The triggering probability means the probability that global temperature crosses the threshold at which WAIS retreat becomes self-sustaining and irreversible on multi-century timescales. The paper uses a coupled tipping-element model incorporating interactions between tipping elements (e.g., Amazon dieback slightly amplifying WAIS triggering probability through global mean temperature). The core result for WAIS is robust to whether or not Amazon and permafrost interactions are included.
- Independence
- Wunderling et al. use a tipping-element network model parameterised from the Armstrong McKay 2022 threshold estimates, which are themselves derived from paleoclimate evidence and process understanding. This is a different approach from IPCC AR6's process-based climate model ensemble, though both draw on overlapping paleoclimate evidence for threshold estimates.
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[2] Science — Armstrong McKay, Staal, Abrams, Winkelmann, Sakschewski, Loriani, Fetzer, Cornell, Rockström, Lenton, 2022 — Exceeding 1.5°C global warming could trigger multiple climate tipping points
Exceeding 1.5°C global warming could trigger multiple climate tipping points- Statistic
WAIS central temperature threshold ~1.5°C (range 1-3°C); 'likely' to be triggered above 1.5°C of global warming; full WAIS collapse would raise sea level by more than 3.3 metres over centuries- Excerpt
“"The West Antarctic Ice Sheet has a central threshold of approximately 1.5°C of global warming above pre-industrial levels, with a range of 1 to 3°C... Above 1.5°C, the WAIS becomes 'likely' to cross its tipping threshold, committing to eventual collapse over decades to millennia and a sea level contribution of 3.3-5.3 metres." ”
- Source data from
- 2022-09-09
- Accessed
- 2026-05-09 · archived copy
- Calculation
- Armstrong McKay et al. 2022 is the most comprehensive recent revision of climate tipping point thresholds, synthesising paleoclimate evidence and process understanding for sixteen tipping elements. The WAIS threshold lowering from the previous Lenton 2008 estimate of ~3-5°C to ~1.5°C was significant: it places the threshold within the Paris Agreement target range, meaning that even the most ambitious emissions reduction targets do not guarantee avoiding WAIS commitment to collapse. The 1-3°C range captures deep uncertainty in the threshold itself.
- Independence
- Armstrong McKay et al. synthesise paleoclimate and process evidence using a different methodology than Wunderling et al.'s probabilistic network model. Both reach compatible conclusions about WAIS proximity to its threshold under current conditions.
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[3] Nature Climate Change — Naughten et al., 2023 — Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century
Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century- Statistic
All four tested emissions scenarios produce similar accelerated Amundsen Sea warming until at least 2045; ice-shelf warming projected at ~triple the historical rate regardless of near-term mitigation- Excerpt
“"These results suggest that mitigation of greenhouse gases now has limited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet... Under all scenarios, the Amundsen Sea is committed to accelerated warming at approximately triple the historical rate until at least 2045." ”
- Source data from
- 2023-10-23
- Accessed
- 2026-05-09 · archived copy
- Calculation
- Naughten et al. 2023 focuses on ocean warming beneath WAIS ice shelves in the Amundsen Sea sector — the primary driver of ice shelf basal melt and the mechanism by which warming triggers WAIS instability. The finding that all emissions scenarios produce similar warming until 2045 is significant: near-term mitigation cannot prevent the accelerated melting already committed by historical emissions. This does not mean full collapse is committed, only that the process driving it is locked in for at least two decades. The paper's single-model design limits certainty, but it uses a high-resolution ocean model specifically designed for Amundsen Sea dynamics.
- Independence
- Naughten et al. use an ocean model focused on the Amundsen Sea specifically, rather than the global climate models used by Wunderling 2025 and Armstrong McKay 2022. The result addresses ice-shelf basal melt rates rather than full tipping point probability, providing a physically independent mechanism-level corroboration.
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[4] Intergovernmental Panel on Climate Change (IPCC), Working Group I, Sixth Assessment Report — Climate Change 2021: The Physical Science Basis — Chapter 9: Ocean, Cryosphere and Sea Level Change
Climate Change 2021: The Physical Science Basis — Chapter 9: Ocean, Cryosphere and Sea Level ChangeSee all 2 Likelier entries citing this source →
- Statistic
Antarctic ice mass loss 'likely' to continue all century; MISI physically plausible and observed; 'low likelihood, high impact' storyline for >1m additional SLR from ice sheet instability; deep uncertainty acknowledged- Excerpt
“"There is medium confidence that significant Antarctic ice mass loss will not involve an abrupt collapse before 2100... Marine Ice Sheet Instability (MISI) is physically plausible, has been observed in Thwaites Glacier, and would result in substantial irreversible sea level rise if triggered... Low-likelihood, high-impact storylines include scenarios leading to more than one metre of additional sea level rise from ice sheet instability before 2100." ”
- Source data from
- 2021-08-09
- Accessed
- 2026-05-09 · archived copy
- Calculation
- IPCC AR6 does not assign a numerical probability to WAIS collapse before 2100, instead using "medium confidence that [abrupt collapse] will NOT happen" — implying some non-trivial probability that it will. The Bamber et al. 2019 structured expert judgment cited by AR6 gave WAIS sea level contribution by 2100 as median 8-18 cm with 95th percentile up to 44-93 cm depending on warming scenario — reflecting deep uncertainty but not ruling out large contributions. IPCC AR6's position is more cautious than Wunderling 2025 because it relies on CMIP model ensembles that do not simulate WAIS collapse, rather than the tipping-point network models used by Wunderling.