Beneath the West Antarctic Ice Sheet: Borehole Analytics and the Revision of Instability Models

Abstract

The Thwaites Glacier in the Amundsen Sea Embayment of West Antarctica represents the single largest source of uncertainty in near-term global sea-level rise projections. Often colloquially termed the "Doomsday Glacier," its stability is governed by complex interactions between the cryosphere and the ocean that occur deep beneath kilometers of ice. This report provides an exhaustive, narrative synthesis of the findings from the International Thwaites Glacier Collaboration (ITGC), specifically focusing on the 2019–2020 MELT project field season and the subsequent seminal publications in Nature by Schmidt et al. (2023) and Davis et al. (2023). By integrating historical glaciological theory with novel in-situ observations from the Icefin submersible and recent modeling advancements from 2024 and 2025, we deconstruct the simplified "linear melting" models of the past. The analysis reveals a hydrographic paradox: while broad-scale basal melting is suppressed by strong density stratification and freshwater insulating layers, the glacier is simultaneously undergoing rapid, structurally directed disintegration via basal crevasses and terraced topography. This report details the logistical triumph of the borehole exploration, the fluid dynamics of the ice-ocean boundary layer, and the evolving scientific consensus regarding Marine Ice Sheet Instability (MISI) and Marine Ice Cliff Instability (MICI). We argue that the trajectory of the West Antarctic Ice Sheet will be defined not by a uniform thermal erosion, but by the chaotic interplay of fracture mechanics and buoyancy-driven convection at the grounding line.

1. Introduction: The Planetary Stakes of the Amundsen Sea

1.1 The Keystone of West Antarctica

The geography of Antarctica is often bifurcated into East and West, separated by the Transantarctic Mountains. While the East Antarctic Ice Sheet sits largely on high ground above sea level, the West Antarctic Ice Sheet (WAIS) is a marine ice sheet, grounded on bedrock that sits well below sea level.¹ At the heart of this marine basin lies the Thwaites Glacier, a colossal ice stream spanning approximately 192,000 square kilometers—an area roughly equivalent to the island of Great Britain or the US state of Florida.³

Thwaites is unique not just for its size, but for its strategic position. It acts as the "keystone" of the WAIS, draining a massive basin into the Amundsen Sea. Glaciologists have long recognized that Thwaites holds a distinct configuration: its grounding line—the precise boundary where the heavy ice lifts off the bedrock and begins to float—sits on a retrograde slope. This means that as one moves inland, the bedrock floor slopes downward, getting deeper.² This geometry creates a potential instability where retreat leads to a thicker ice front, which flows faster, causing further retreat—a positive feedback loop known as Marine Ice Sheet Instability (MISI).²

The stakes of this instability are planetary in scale. Thwaites Glacier alone contains enough ice to raise global sea levels by approximately 65 centimeters (over 2 feet).⁴ However, its role as a buttress for the neighboring ice meant that its collapse could trigger a broader destabilization of the entire WAIS, potentially releasing enough water to raise sea levels by an additional 3.3 meters (roughly 10 to 11 feet) over the coming centuries.⁶ Currently, the glacier accounts for approximately 4% of all global sea-level rise, a contribution that has more than doubled since the 1990s.⁷

1.2 The "Doomsday" Narrative and Scientific Responsibility

In recent years, Thwaites has acquired the media moniker of the "Doomsday Glacier." While effective at communicating urgency, this term often obscures the nuanced physical reality of glacial retreat. The popular narrative suggests a simple binary: the glacier is either stable, or it is collapsing catastrophically. The scientific reality, however, is a complex continuum governed by thermodynamics, fluid mechanics, and structural geology.

The "Doomsday" scenario relies heavily on the hypothesis of rapid, runaway collapse, potentially accelerated by mechanisms such as Marine Ice Cliff Instability (MICI), where towering ice cliffs crumble under their own weight.⁸ However, verifying these hypotheses has been historically impossible due to the inaccessibility of the grounding zone. Until recently, our view of Thwaites was limited to satellite altimetry (measuring surface height changes) and radar data (measuring internal layers). What was happening beneath the ice—at the critical interface where warm ocean water meets the glacier—remained a "black box" in climate models.

The International Thwaites Glacier Collaboration (ITGC) was formed to open this black box. By deploying teams to the most remote region of the Antarctic continent, the collaboration aimed to replace speculation with in-situ data. The findings from these expeditions, particularly the deployment of the Icefin robot, have fundamentally altered our understanding of the system. They reveal that the "Doomsday" is not a singular event of thermal annihilation, but a complex, heterogeneous process where the glacier protects itself in some areas while shattering in others.³

This report serves as a narrative academic inquiry into these findings. It is written for the student of Earth systems who wishes to understand not just that the ice is melting, but how. It explores the physics of the boundary layer, the engineering of the hot water drill, and the human endeavor of conducting science at the bottom of the world.

2. Historical Context: The Theory of the "Weak Underbelly"

2.1 The Early Warnings: Mercer and Hughes

The scientific anxiety surrounding West Antarctica is not a product of the 21st century. It dates back to the seminal work of glaciologists in the 1970s. In 1978, John Mercer of Ohio State University published a prescient paper warning of a "major disaster"—a rapid 5-meter rise in sea level caused by the deglaciation of West Antarctica.¹ Mercer identified that the marine nature of the ice sheet made it uniquely vulnerable to warming, specifically linking the threat to rising atmospheric carbon dioxide levels long before the topic entered the mainstream political consciousness.

Three years later, in 1981, Terry Hughes of the University of Maine coined the term "weak underbelly" to describe the Amundsen Sea sector.¹ Hughes identified the Thwaites and Pine Island glaciers as the vulnerable soft tissue of the continent. Unlike the ice shelves in the Ross and Weddell seas, which are constrained by large embayments and protected by cold water, the Amundsen Sea glaciers are exposed to the open circulation of the Southern Ocean. Hughes hypothesized that these glaciers could lose their grip on the submarine mountains that pin them in place, leading to a disintegration that would "gut" the ice sheet from the inside out.¹

2.2 The Shift from Atmosphere to Ocean

For decades, the mechanisms proposed by Mercer and Hughes remained theoretical. The lack of observational data meant that early models often focused on atmospheric warming—surface melting—as the driver of retreat. This perspective shifted dramatically in the 1990s and 2000s with the advent of satellite monitoring and oceanographic profiling.

Researchers like Eric Rignot at NASA began to document a rapid acceleration in the flow speeds of Thwaites and Pine Island glaciers.¹ Simultaneously, oceanographers identified the culprit: it was not warm air melting the glacier from above, but warm water melting it from below. The ocean encircling Antarctica is stratified. The surface waters are cold and fresh, but deep below lies the Circumpolar Deep Water (CDW)—a water mass that is relatively warm (around 1°C to 2°C) and salty.²

The prevailing theory evolved to suggest that shifting wind patterns, potentially driven by the hole in the ozone layer and greenhouse gas warming, were forcing this warm CDW up onto the continental shelf and into the deep cavities beneath the ice shelves.² This "ocean forcing" hypothesis became the central paradigm of West Antarctic glaciology. It posited that the ocean was acting as a heat source, eating away at the grounding lines and triggering the MISI feedback loops predicted by theory.

2.3 The Data Gap

Despite this theoretical convergence, a critical gap remained. No one had ever measured the conditions at the grounding line of Thwaites Glacier. The models assumed a linear relationship: if the water in the bay was warm, the water at the grounding line was warm, and the melt rate would be high and uniform.

This assumption of uniformity—or "linear friction"—was a necessary simplification for computer models that could not resolve the turbulent details of water flow at the scale of centimeters. However, as the ITGC would discover, the grounding zone is anything but uniform. It is a chaotic, dynamic environment where the physics of melting changes dramatically over distances of just a few meters.

3. The Physics of the Abyss: Grounding Zones and Retrograde Slopes

To understand the findings of the MELT project, one must first grasp the physical environment of the Thwaites grounding zone. This is a world defined by extreme pressure, total darkness, and the interactions of ice, water, and rock.

3.1 The Geometry of Instability

The concept of the "grounding line" is central to the fate of Thwaites. This is the boundary where the glacier, flowing off the continent, loses contact with the bedrock and becomes a floating ice shelf.

• Buttressing: The floating ice shelf acts as a brake. It pushes back against the grounded ice, slowing its flow into the sea. This resistive force is known as "buttressing".⁶

• The Retrograde Slope: As noted, Thwaites sits on a bed that deepens inland. At the current grounding line, the bed is roughly 600 meters below sea level. Further upstream, the basin plunges to depths of 1.5 kilometers or more.¹¹

Marine Ice Sheet Instability (MISI): The physics of ice flow dictates that the flux (the amount of ice moving across the grounding line) is a function of ice thickness. On a retrograde slope, if the grounding line retreats slightly, it moves into deeper water where the ice is thicker. Thicker ice allows for a higher flux. The glacier speeds up, stretching and thinning the ice, which causes the grounding line to retreat further. This self-reinforcing cycle suggests that once retreat begins on a retrograde slope, it can become irreversible, independent of the original climate forcing.²

3.2 Circumpolar Deep Water (CDW) and Ocean Heat Transport

The engine driving this retreat is the Circumpolar Deep Water. In most of the world's oceans, deep water is cold. However, in the Southern Ocean, the "Deep Water" is actually warmer than the surface water because it originates from mid-latitude waters that have sunk and traveled south.

• The Pathway: The CDW sits off the continental shelf. Changes in the westerly winds around Antarctica, linked to climate change, act to pump this water onto the shelf.

• The Cavity: Once on the shelf, the dense, salty CDW flows along the seafloor, following deep troughs (submarine canyons) that lead directly to the grounding lines of glaciers like Thwaites.¹²

• Thermal Potential: While the water is only a few degrees above freezing (e.g., 1.5°C), the specific heat capacity of water is immense. A continuous stream of this water acts like a conveyor belt of energy, capable of delivering vast amounts of heat to the ice base.¹³

3.3 The Ice-Ocean Boundary Layer

The critical physics occurs in the final few centimeters where the water touches the ice—the "boundary layer."

• Phase Change: To melt ice, heat must transfer from the water into the ice crystal structure to break the bonds. This requires energy (latent heat of fusion).

• Thermodynamic Barrier: As ice melts, it releases fresh water. This freshwater is cold (at the freezing point) and buoyant. If the water is still, this freshwater adheres to the ice, creating a buffer zone. This buffer is cold and insulates the ice from the warm CDW below.

• Turbulence as a Scrubbing Brush: For rapid melting to occur, the ocean must be turbulent. Eddies and currents act like a scrubbing brush, sweeping away the cold freshwater layer and bringing new, warm water into contact with the ice.

The major scientific uncertainty prior to 2020 was the state of this boundary layer. Was the cavity beneath Thwaites a turbulent washing machine, scrubbing the ice efficiently? Or was it a stagnant pool where stratification protected the glacier? The models assumed the former. The observations would reveal the latter—with a deadly twist.

4. The International Thwaites Glacier Collaboration (ITGC): A Logistic Odyssey

4.1 The Campaign Strategy

The ITGC was established as a joint US-UK mission to address the uncertainties surrounding Thwaites. It is a scientific siege, involving ships, aircraft, and traverse teams. The MELT project (Melting at Thwaites grounding zone and its control on sea level) was arguably the most ambitious component, tasked with drilling through the ice to deploy sensors directly into the grounding zone.³

This required establishing a field camp in the "deep field"—a location hundreds of kilometers from the main research stations (McMurdo or Rothera), accessible only by ski-equipped aircraft like the Twin Otter or Basler.¹⁴

4.2 Life on the Ice: The "Flubber" and the Fury

The physical reality of conducting this research is grueling. The field teams, comprising scientists, engineers, and mountaineers, live in tents on the flat, white expanse of the ice shelf. The environment is actively hostile. Temperatures can drop below -40°C, and storms can rage for days, burying the camp in snowdrifts that must be manually dug out.¹⁵

The centerpiece of the operation is the Hot Water Drill. Unlike mechanical drills that cut ice, this system melts it.

• The "Flubber": The heart of the system is a 10,000-liter flexible water tank, nicknamed the "flubber" for its resemblance to the amorphous substance from the 1997 film Flubber (or the original The Absent-Minded Professor). This black bladder sits on the snow surface and stores the drilling fluid.¹⁶

• The Cycle: The process begins by melting snow to fill the flubber. This water is then pumped through high-powered diesel boilers, heated to nearly boiling (around 80°C), and sprayed down a hose to melt the borehole.¹⁶

• The Risk: The operation is a thermodynamic tightrope. The drilling water must be kept hot and circulating. If a storm hits and the boilers must be shut down, the water in the hose and the flubber can freeze. In the intense cold of the Antarctic interior, a frozen system can end a season instantly.

During the 2019–2020 season, the MELT team faced exactly these conditions. A severe storm brought hurricane-force winds, burying the camp. The team spent days digging out the equipment, battling to keep the flubber liquid. The tension was palpable; the window for drilling is short, and the "flubber" is the lifeline of the entire scientific mission.¹⁵

4.3 The Borehole: A Transient Portal

Once the weather cleared, the drill successfully penetrated approximately 600 meters of ice, creating a hole roughly 30-40 centimeters in diameter.⁹

• The Clock: The moment the drill nozzle is removed, the clock starts ticking. The ice shelf, with a core temperature of around -20°C, acts as a heat sink. The borehole immediately begins to refreeze, narrowing the diameter.

• The Deployment: This creates a "Cinderella" constraint for the deployment of instruments. The robot Icefin had to be lowered, complete its mission, and be retrieved before the hole shrank too much to allow its return. The margin for error was millimeters.

5. Engineering the Abyss: The Icefin Submersible

5.1 The Need for a New Class of Robot

Exploring the cavity beneath an ice shelf presents a unique set of engineering challenges that traditional oceanographic tools cannot meet.

• Size: Standard Autonomous Underwater Vehicles (AUVs) like the REMUS class are torpedo-shaped but often too large (in diameter) to fit through a field-drilled borehole.

• Tethering: Remotely Operated Vehicles (ROVs) are typically tethered by heavy cables. Dragging kilometers of heavy cable through a narrow, freezing hole is logistically impossible.

• Agility: The mission required not just swimming, but hovering. To understand the boundary layer, the vehicle needed to nose right up to the ice face and hold position, measuring turbulence at the millimeter scale.

To solve this, Dr. Britney Schmidt (then at Georgia Tech, now Cornell) and her team developed Icefin.

5.2 Technical Specifications of Icefin

Icefin is a hybrid vehicle—a "remotely operated" vehicle that has significant autonomy, designed specifically for borehole deployment.¹⁸

Table 1: Icefin Vehicle Specifications

Feature	Specification	Purpose
Form Factor	Modular, Pencil-shape	Fits through standard 30-50 cm boreholes.
Length	~3.5 meters (12 feet)	Allows for substantial battery and sensor payload.
Diameter	23 centimeters (9 inches)	Optimized for narrow drill holes to minimize fuel use.
Weight	130 kg (286 lbs)	Transportable by small aircraft and hand-deployable.
Depth Rating	1,500 meters	Capable of reaching the deep grounding lines of WAIS.
Range	~3.5 - 5 kilometers	Allows surveys extending away from the borehole insertion point.
Propulsion	5 thrusters (Holonomic)	Allows vertical hovering, strafing, and pitch control.

5.3 The Sensor Suite: A Robotic Oceanographer

Icefin is not just a camera; it is a mobile laboratory. For the Thwaites mission, it carried a payload designed to dissect the physics of melting.¹⁸

1. CTD (Conductivity, Temperature, Depth): The fundamental tool of oceanography. It measures the salinity and temperature of the water to high precision, allowing scientists to identify water masses (e.g., distinguishing meltwater from CDW).

2. Doppler Velocity Log (DVL) & ADCP: These acoustic sensors measure the speed of the water moving past the robot and the robot's speed over the seafloor. This was crucial for measuring the "friction velocity"—the turbulence of the water hitting the ice.

3. Sonar (Forward and Sidescan): Since the cavity is pitch black, sonar provides the "eyes" to map the topography of the ice and seafloor at ranges beyond the reach of lights.

4. Geochemical Sensors: Sensors for Dissolved Oxygen (DO) and Organic Matter (fDOM) help trace the source of the water and its biological history.¹⁸

5.4 The Deployment

In January 2020, the MELT team lowered Icefin through the 600-meter borehole. As it emerged into the ocean cavity below, it entered a world never before seen by human eyes. The data it beamed back up the fiber-optic tether would contradict nearly every assumption glaciologists had held about the "Doomsday Glacier."

6. The 2023 Findings: A Hydrographic Paradox

The analysis of the data collected by Icefin and the accompanying ocean moorings culminated in two landmark papers published in Nature in February 2023. These papers, led by Dr. Peter Davis (BAS) and Dr. Britney Schmidt (Cornell), presented a complex, contradictory picture of the melting process.

6.1 The "Insulating Layer" (Davis et al. 2023)

The first major finding, detailed by Peter Davis and colleagues, concerned the broad-scale oceanography of the cavity.

• The Expectation: Models predicted that the warm CDW (approx. 2°C above freezing) would be in direct, turbulent contact with the ice base, driving rapid melting everywhere.

• The Observation: The team found that while the deep water was indeed warm, the water immediately adjacent to the ice was unexpectedly cold and fresh.³

The Mechanism of Stratification: As the glacier melts, it releases fresh water. Fresh water is significantly less dense than the salty ocean water. Under the flat sections of the ice shelf, this fresh meltwater did not mix away. Instead, it formed a stable, buoyant layer—a "stratified" boundary layer—that hugged the underside of the ice.²⁰

• Suppression of Turbulence: This density difference acted like a shield. It suppressed the vertical mixing (turbulence) that is required to transfer heat from the warm deep water up to the ice.

• Diffusive Convection: Instead of vigorous turbulent melting, the heat transfer was dominated by "diffusive convection" or molecular diffusion—a much slower process.²⁰

• The Result: The melt rate calculated for these flat areas was only 2 to 5 meters per year. This was significantly lower—by nearly an order of magnitude—than what standard "linear friction" models had predicted for water of that temperature.⁹

This finding was, on the surface, good news. It suggested that the "blowtorch" effect on the main body of the ice shelf was dampened by its own meltwater. The glacier was effectively insulating itself.

6.2 The Structural Attack (Schmidt et al. 2023)

However, the second paper, led by Britney Schmidt, shattered any sense of complacency. While Davis et al. looked at the water column, Schmidt et al. used Icefin to examine the ice structure itself. The robot revealed that the underside of Thwaites is not a flat plane. It is a chaotic landscape of "staircase" terraces and deep, inverted canyons (crevasses).³

The "Staircase" Topography:

Icefin's sonar revealed a series of terraced steps carved into the ice. These terraces had flat roofs (treads) and steep vertical walls (risers).

• The Flat Treads: Here, the physics described by Davis et al. applied. The water was stratified, and melting was slow.

• The Vertical Risers: On the vertical faces, the physics inverted. The buoyant fresh meltwater could not sit still; gravity forced it to rush upward along the vertical wall.

• Buoyancy-Driven Convection: This upward flow created a turbulent plume. The plume entrained warm water from the surroundings and slammed it against the ice. This disrupted the insulating layer.¹³

• The Result: Melt rates on the vertical faces and within the crevasses were measured at 30 meters per year or more—ten times faster than on the flat sections.¹³

The Crevasse Feedback Loop:

Crucially, Icefin observed that this rapid melting was widening the basal crevasses.

• Mechanism: Warm water was being pumped into the cracks, melting the sidewalls outward. This not only removed mass but also weakened the structural integrity of the ice shelf.³

• Heat Funneling: The geometry of the crevasses acted to funnel heat into the weakest parts of the glacier. The deeper the crack, the stronger the buoyancy-driven flow, and the faster the melting.

6.3 The Synthesis: Heterogeneous Melting

The combined lesson of the 2023 papers is that melting is heterogeneous. It is not a uniform sanding down of the ice; it is a targeted structural attack. The glacier is melting slowly on its strong, flat surfaces, but it is being rapidly dismantled at its weak points (cracks and terraces).

This explains why the glacier is retreating rapidly despite the "suppressed" average melt rates. The structural failure of the ice shelf—driven by crevasse widening—is likely the precursor to the broader collapse of the system. The "insulating layer" is a false security; the damage is being done in the cracks.

7. Future Modeling and The 2024 Updates

The ITGC findings have forced a reckoning in the glaciological modeling community. The "bath tub" models of the past, which treated the cavity as a simple box of water, are no longer sufficient.

7.1 From Linear Friction to Slope-Dependent Melting

Future models must incorporate slope-dependent melting. As Icefin showed, the melt rate is a function of the ice angle.

• Flat Ice: Low melt (stratified).

• Sloped/Vertical Ice: High melt (convective). This implies that as a glacier roughens and fractures, it will melt faster. This is a positive feedback mechanism that current climate models largely ignore.¹³

7.2 Re-evaluating Marine Ice Cliff Instability (MICI)

One of the most feared scenarios for Thwaites is the Marine Ice Cliff Instability (MICI). This hypothesis posits that if the floating ice shelf disintegrates completely, it will expose a towering cliff of grounded ice (taller than 100 meters above sea level) that is structurally unstable. This cliff would collapse, exposing a new cliff, leading to a runaway retreat.

The 2024 Dartmouth Study: However, new research published in 2024 and 2025 has moderated this fear. A study led by researchers at Dartmouth College used high-resolution models to simulate the physics of ice cliff failure.⁸

• Viscous Relaxation: The study found that ice is not just a brittle solid; it flows. As a cliff becomes unstable, the ice might deform and thin (viscous relaxation) fast enough to reduce the cliff height before catastrophic collapse occurs.

• Debris Stabilization: The collapse of an ice cliff creates a pile of debris (melange) at the base. This debris can provide back-pressure, stabilizing the cliff face.

• Conclusion: The study suggests that the extreme MICI scenarios—which predicted sea level rise of 2+ meters by 2100—are less likely. The retreat will likely be driven by MISI (slope instability) and basal melting rather than sheer mechanical cliff failure.⁸

7.3 Glacial Isostatic Adjustment (GIA)

Another factor gaining attention in 2024 is the rebound of the Earth's crust. As the heavy ice melts, the bedrock beneath it rises—a process called Glacial Isostatic Adjustment (GIA).²⁴

• The Stabilizing Effect: In theory, rapid uplift could raise the seabed enough to re-ground the glacier, pinning the grounding line and slowing retreat.

• The Destabilizing Reality: However, recent analyses suggest that for Thwaites, the retreat is happening too fast for GIA to catch up. Furthermore, the uplift might displace water from the basin into the global ocean, slightly adding to sea level rise. The "solid earth" is moving, but likely not fast enough to save the ice sheet.²⁴

8. Conclusion: A New Era of Glacial Forensics

The journey from the theoretical warnings of Mercer and Hughes in the 1970s to the high-resolution observations of Icefin in the 2020s marks a maturing of glaciological science. We have moved from low-resolution anxiety to high-definition understanding.

The "Doomsday Glacier" moniker, while alarmist, points to a genuine planetary threat. Thwaites is indeed retreating, and the mechanisms driving that retreat are now laid bare. The 2023 ITGC findings reveal a system that is paradoxically resilient and fragile. The thermodynamics of stratification attempt to shield the ice, but the hydrodynamics of buoyancy and fracture exploit every weakness.

The "insulating layer" discovered by Davis et al. explains why the glacier hasn't vanished yet, but the "terrace melting" discovered by Schmidt et al. explains why it is breaking apart. The ocean is effectively using the glacier's own geometry against it, turning every crack into a heat funnel.

For the global community, the implications are clear. The timeline of sea-level rise will not be determined by a simple linear response to air temperature. It will be determined by the fracture toughness of ice and the turbulent flow of water in the dark, frozen canyons of West Antarctica. The "flubber," the drill, and the robot have done their job; they have provided the data. Now, the burden shifts to the modelers and policymakers to act on the forensic evidence of a crime scene where the victim is the ice, and the culprit is the warming ocean.

9. Appendix: Data Tables and Technical Summaries

Table 2: Comparison of Melt Mechanisms Identified

Feature	Mechanism	Observed Rate	Key Physics
Flat Ice Base	Diffusive Convection	2 – 5 m/year	Stratified freshwater layer suppresses turbulence. Low friction velocity.
Vertical Crevasse Wall	Buoyancy-Driven Convection	> 30 m/year	Rising meltwater plume creates shear, entraining warm water. High heat transfer.
Sloped Terrace	Mixed Regime	Variable	Melt rate increases with the sine of the slope angle. Scallop formation.

Table 3: Sea Level Rise Potential (Amundsen Sea Sector)

Source	Potential Rise (Eustatic)	Timeframe of Concern	Primary Driver
Thwaites Glacier (Direct)	~65 cm (2.1 ft)	Centuries	MISI, Basal Melting
West Antarctic Ice Sheet (Total)	~3.3 m (10.8 ft)	Millennia (or Centuries in worst case)	Collapse of buttressing ice shelves
Global Rate (Current)	~4.5 mm/year	Present Day	Thermal expansion + melt (Thwaites is ~4%)

(Note: Sea level rise potentials are based on total ice volume equivalents derived from bedrock geometry.⁴)

Works cited

1. As 'Doomsday' Glacier Melts, Can an Artificial Barrier Save It? - e360-Yale, accessed January 31, 2026, https://e360.yale.edu/features/thwaites-glacier-pine-glacier-antarctica-geoengineering

2. Marine Ice Sheet instability - Antarctic Glaciers, accessed January 31, 2026, https://www.antarcticglaciers.org/antarctica-2/west-antarctic-ice-sheet-2/marine-ice-sheets/

3. New close-up view of melting beneath Thwaites Glacier - British Antarctic Survey - News, accessed January 31, 2026, https://www.bas.ac.uk/media-post/new-close-up-view-of-melting-beneath-thwaites-glacier/

4. Antarctica's Thwaites Glacier and sea-level rise, accessed January 31, 2026, https://thwaitesglacier.org/findings

5. Stabilizing effect of mélange buttressing on the marine ice-cliff instability of the West Antarctic Ice Sheet - Potsdam Institute for Climate Impact Research, accessed January 31, 2026, https://www.pik-potsdam.de/~anders/publications/schlemm_feldmann22.pdf

6. The International Thwaites Glacier Collaboration | National Snow and Ice Data Center, accessed January 31, 2026, https://nsidc.org/news-analyses/news-stories/international-thwaites-glacier-collaboration

7. Scientists drill for first time on remote Antarctic Glacier, accessed January 31, 2026, https://thwaitesglacier.org/news/scientists-drill-first-time-remote-antarctic-glacier

8. New research offers hope on sea-level rise, although risks remain - ITGC Thwaites Glacier, accessed January 31, 2026, https://thwaitesglacier.org/news/research-offers-hope-sea-level-rise-risks-remain

9. Scientists named on TIME100 list for Antarctic research, accessed January 31, 2026, https://www.bas.ac.uk/media-post/dr-peter-davis-and-dr-britney-schmidt-named-on-the-time100-list-for-research-on-thwaites-glacier/

10. Stratified suppression of turbulence in an ice shelf basal melt parameterisation - TC, accessed January 31, 2026, https://tc.copernicus.org/articles/19/5827/2025/

11. Thwaites Glacier thins and retreats fastest where ice-shelf channels intersect its grounding zone - TC, accessed January 31, 2026, https://tc.copernicus.org/articles/18/4971/2024/

12. International Thwaites Glacier Collaboration - British Antarctic Survey - Project, accessed January 31, 2026, https://www.bas.ac.uk/project/international-thwaites-glacier-collaboration/

13. Nature: Heterogeneous melting near the Thwaites Glacier grounding line, accessed January 31, 2026, https://schmidt.astro.cornell.edu/thwaites_publications/nature-heterogeneous-melting-near-the-thwaites-glacier-grounding-line/

14. When Ice Sheets and Active Volcanoes Collide - Department of Geoscience, accessed January 31, 2026, https://geoscience.wisc.edu/wp-content/uploads/2025/02/Outcrop2024MergedCompressed2.pdf

15. Antarctica melting: Climate change and the 'doomsday glacier' | RNZ News, accessed January 31, 2026, https://www.rnz.co.nz/news/world/408516/antarctica-melting-climate-change-and-the-doomsday-glacier

16. The BAS ice-shelf hot-water drill: design, methods and tools, accessed January 31, 2026, https://nora.nerc.ac.uk/507364/1/a68a030.pdf

17. Working in ice-solation | New Zealand Police, accessed January 31, 2026, https://www.police.govt.nz/news/ten-one-magazine/working-ice-solation

18. ICEFIN – Planetary Habitability and Technology Lab - Cornell University, accessed January 31, 2026, https://schmidt.astro.cornell.edu/icefin/

19. Icefin Robot - Andrew Mullen, accessed January 31, 2026, https://andrewdmullen.github.io/projects/

20. The melting underneath the Thwaites Glacier is complicated - Physics Today, accessed January 31, 2026, https://physicstoday.aip.org/news/the-melting-underneath-the-thwaites-glacier-is-complicated

21. Suppressed basal melting in the eastern Thwaites Glacier grounding zone - NYU Scholars, accessed January 31, 2026, https://nyuscholars.nyu.edu/en/publications/suppressed-basal-melting-in-the-eastern-thwaites-glacier-groundin

22. Stratified suppression of turbulence in an ice shelf basal melt parameterisation - TC, accessed January 31, 2026, https://tc.copernicus.org/articles/19/5827/2025/tc-19-5827-2025.pdf

23. Study Finds Highest Prediction of Sea-Level Rise Unlikely | Dartmouth, accessed January 31, 2026, https://home.dartmouth.edu/news/2024/08/study-finds-highest-prediction-sea-level-rise-unlikely

24. How Soon Will the Seas Rise? | Quanta Magazine, accessed January 31, 2026, https://www.quantamagazine.org/how-soon-will-the-seas-rise-20251020/