Warm seawater is creeping beneath Antarctica’s Thwaites Glacier, which is accelerating the melt of one of the planet’s most critical ice masses. That glacier, roughly the size of Florida, holds enough ice to raise global sea levels over two feet if it collapses completely. But worse, if that glacier collapses, it could trigger a wider collapse of the WAIS, unleashing as much as 15 feet of sea level rise over centuries-a scenario that paleoclimate evidence supports during similar events 120,000 years ago.
Recent studies have shown that tidal currents push warm Circumpolar Deep Water far beneath the glacier’s underbelly. Where tides lift sections of Thwaites off the seafloor, channels open for this heat-laden water to intrude and cause what scientists term “vigorous melting.” Research into grounding-zone dynamics shows feedback between melt rates and ice geometry that may lead to tipping-point behavior: small rises in ocean temperature can make the system switch from stable to runaway intrusion-even on bed slopes previously thought secure. This could account both for past models of the ice sheet underestimating retreat rates and for current projections being conservative.
To face these uncertainties, a team of nearly 40 researchers has set sail from New Zealand armed with airborne radar systems able to penetrate more than a mile of ice. These radar surveys build on techniques refined in large-scale ice-stream mapping projects and will create detailed profiles of the ice thickness, bed topography, and internal layering. These types of data are needed to constrain models of how Thwaites will respond to continued ocean warming, as simulations suggest can reach 2 °C above pre-industrial levels in the Amundsen Sea by 2100, regardless of moderate emissions cuts.
One of the most innovative tools on the expedition comes from an unlikely source: the seals. Building on a 20-year French–Australian program, scientists will attach miniaturized CTD-SRDLs to Weddell and southern elephant seals. These instruments, proven to provide ±0.03 °C temperature accuracy and ±0.05 g/kg salinity precision, will obtain thousands of vertical profiles from regions unreachable by ships or autonomous floats but, instead, under seasonal sea ice and along the Antarctic continental shelf. The foraging patterns of the seals naturally take them to oceanographic “hot spots,” where the variations in temperature, salinity, and currents are the greatest.
These seal-borne data will be telemetered in near real time via the Argos satellite system to the World Meteorological Organization, feeding directly into global ocean forecasting models. Past deployments have elucidated routes of warm water onto Antarctic shelves, mapped the position of Antarctic Circumpolar Current fronts, and even identified new sources of Antarctic Bottom Water formation. In the context of Thwaites, these observations could pinpoint the precise routes and depths of warm-water intrusions, informing geoengineering proposals such as submarine curtains designed to block or divert heat transport.
Geoengineering, for its part, is contentious. Designs such as bubble curtains or fabric barriers to protect glacier fronts from warm currents are daunting technically and tend to divert attention from emission reduction. But proponents say that in the context of polar tipping points like WAIS collapse, these interventions might be the only method to “buy time.” As climate economist Gernot Wagner has said, these measures are “not a solution to climate change-at best, it’s a painkiller,” buying time for humanity to work on the root cause and managing the immediate damage.
Paleoclimate records drive home the stakes. Sediment cores from the Amundsen Sea reveal that past retreats of the WAIS were accompanied by catastrophic geological activity-earthquakes, volcanic eruptions, landslides, and tsunamis-triggered by the removal of ice’s immense weight. These events reshaped coastlines and ecosystems in geologically rapid bursts, a reminder that ice-sheet collapse is not a slow-motion disaster but a cascade of abrupt changes with global repercussions.
The current mission to Thwaites uses a combination of airborne radar mapping, seal-borne oceanography, and advanced modeling of grounding-zone melt dynamics to attempt to resolve some critical unknowns about its stability. The resulting insights feed into global climate models, refine sea-level rise projections, and inform both adaptation strategies and potential engineering interventions. In the race against time, the fusion of cutting-edge technology and natural allies may yield perhaps the clearest window ever into the hidden processes beneath the “Doomsday Glacier.”
