Previous Doomsday Glacier Collapses Are a Warning for the Future

Coverage from Nature, Phys.org, The Watchers, Gizmodo, and The Scotsman reports that a new model of Antarctica's Thwaites Glacier incorporating seawater intrusion beneath grounded ice projects up to approximately 30 millimeters of sea-level rise by 2100 from that glacier alone, roughly twice the earlier average projection in the scenario its authors examined. Simultaneously, research published in Nature examines seafloor clay records revealing repeated loss of the West Antarctic Ice Sheet's Amundsen Sea sector during late Pleistocene interglacials, indicating the ice sheet has collapsed multiple times in past warm periods. The Scotsman frames these findings against the backdrop of the ongoing COP climate summit, describing the glacier as sounding a terrifying warning while international negotiations dither. Gizmodo headlines that previous Doomsday Glacier collapses serve as a warning for the future, connecting the paleoclimate evidence with the updated modeling.

The coverage emphasizes two converging lines of evidence: forward-looking modeling that accounts for previously underrepresented physical processes, and backward-looking geological records that confirm the ice sheet's instability during past warm intervals. Nature's publication of the seafloor clay study provides the peer-reviewed paleoclimate foundation, while The Watchers details the modeling advance that allows seawater to seep beneath grounded ice, a mechanism that accelerates retreat. Phys.org reports on the same seafloor clay findings, noting they reveal past dramatic ice loss in West Antarctica. The Scotsman adds political context by linking the scientific warnings to the COP summit's perceived lack of urgency. Gizmodo synthesizes both threads for a general audience, highlighting the warning from past collapses.

The context a reader needs centers on Thwaites Glacier's nickname as the Doomsday Glacier, earned because its collapse could trigger broader West Antarctic Ice Sheet destabilization. The Amundsen Sea sector, where Thwaites sits, holds enough ice to raise global sea levels by several meters if fully lost. Late Pleistocene interglacials were periods warmer than pre-industrial times but cooler than projected future warming under high-emission scenarios, making them imperfect but instructive analogs. The new model's inclusion of seawater intrusion beneath grounded ice addresses a known gap: earlier models often treated the grounding line as a fixed boundary, whereas observations show warm ocean water can penetrate inland, melting ice from below and accelerating retreat. The COP summit context underscores the policy relevance, as current national pledges fall short of limiting warming to levels that might preserve the ice sheet.

What to watch next based on stated facts includes further peer review and replication of the new modeling projections, integration of the seawater intrusion mechanism into broader ice sheet models used for IPCC assessments, and whether the paleoclimate evidence from seafloor cores prompts revisions to ice sheet stability thresholds in climate policy discussions. The COP summit's outcomes regarding emission reduction commitments will determine how closely future warming tracks the scenarios that drove past collapses. Coverage does not yet specify whether the 30-millimeter projection represents a central estimate or an upper bound, nor does it detail the specific emissions scenario used. The timeline for potential collapse remains uncertain, with the coverage indicating the paleoclimate record shows repeated loss during interglacials but not the precise rate of those past collapses.