Thwaites Glacier: Melting From Below

Scientists have long watched the Thwaites Glacier in West Antarctica with concern, but recent data gathered from deep beneath the ice has shifted the narrative from worry to alarm. New research utilizing advanced underwater robotics has confirmed that warm ocean water is channeling into cracks at the glacier’s base, accelerating melting in ways previous computer models did not predict. This process threatens to destabilize a massive ice shelf often referred to as the “Doomsday Glacier.”

The Icefin Mission: Seeing What Satellites Cannot

For decades, glaciologists relied on satellite imagery to track the retreat of Thwaites. While satellites are excellent at measuring surface area and speed, they cannot see what is happening hundreds of meters below the surface where the ice meets the sea. To solve this, a team of scientists from the U.S. and the U.K., part of the International Thwaites Glacier Collaboration, deployed a pencil-shaped robot named Icefin.

Developed by a team at Cornell University, Icefin was lowered through a borehole drilled nearly 2,000 feet (600 meters) through the ice. Once it reached the water below, it navigated to the “grounding line.” This is the critical zone where the glacier lifts off the bedrock and begins to float on the ocean.

What the Robot Found

Icefin captured high-definition video and salinity data that revealed a complex and rapidly changing environment. The robot observed that the base of the glacier is not a smooth sheet of ice melting uniformly. Instead, it is comprised of:

• Deep Crevasses: Large cracks opening upward into the ice.
• Staircase Formations: Terraced patterns carved into the underbelly of the glacier.
• Warm Water Intrusion: Salty, relatively warm water moving rapidly through these cracks.

This topography is fatal to the ice shelf. The complex shapes increase the surface area exposed to the ocean, while the cracks allow warm water to penetrate deeper into the structure than previously thought possible.

The Mechanics of "Vigorous Melting"

The snippet provided highlights “warm water intrusion,” but the specifics of how this works are what terrify climate scientists. The water circulating beneath Thwaites is Circumpolar Deep Water (CDW). While “warm” in this context is only a few degrees above freezing, it is significantly warmer than the ice itself.

Tidal Pumping

Recent studies published in journals like Nature and PNAS explain a phenomenon called “tidal pumping.” As the tide rises and falls, it acts like a giant bellows. It forces high-pressure warm seawater miles inland beneath the ice sheet. This water rushes into the cracks and fissures Icefin identified.

When the water retreats during low tide, the fresh water created by the melting ice remains trapped. However, the damage is done. The warm water weakens the structural integrity of the glacier from the inside out. This creates a feedback loop:

1. Warm water enters cracks.
2. The cracks widen and melt upward.
3. The structural bond of the ice weakens.
4. Large chunks of ice are more likely to fracture and break off into the sea.

This suggests that Thwaites is not just melting; it is shattering. The rate of melting in these cracks was found to be much higher than the melting rate of the flat ice surfaces.

Why Thwaites is the "Doomsday Glacier"

The term “Doomsday Glacier” is not just a dramatic nickname. It refers to the glacier’s keystone role in the West Antarctic Ice Sheet. Thwaites is massive—roughly the size of Florida or Great Britain. If Thwaites were to collapse entirely, the physical implications would be global and severe.

Direct and Indirect Impact

• Direct Contribution: Thwaites currently contributes about 4% of all global sea-level rise. If it melts completely, it holds enough water to raise global sea levels by approximately 2 feet (65 centimeters).
• The Cork in the Bottle: The greater danger is structural. Thwaites sits in a deep basin and acts as a dam, holding back the vast ice of the West Antarctic Ice Sheet. Without Thwaites blocking the exit, these inland glaciers would accelerate their flow into the ocean.
• Total Potential Rise: If the destabilization of Thwaites triggers the collapse of the surrounding ice sheet, it could eventually lead to a sea-level rise of nearly 10 feet (3 meters).

Comparing Models vs. Reality

Before the Icefin deployment, climate models assumed a linear rate of melting based on water temperature and flow. The reality discovered by the underwater robots is much more chaotic.

While the overall melting rate in some flat areas was actually slower than models predicted, the localized melting in cracks and crevasses was much faster. This uneven melting is dangerous because it compromises the stability of the ice shelf faster than simple volume loss would suggest. It is similar to how a few strategic cracks in a building’s foundation can bring down the structure even if 90% of the concrete remains untouched.

Scientists are now racing to update prediction models with this new data. The consensus is shifting toward the idea that the shelf could break apart within decades rather than centuries.

Frequently Asked Questions

Where exactly is the Thwaites Glacier located?

Thwaites Glacier is located in West Antarctica, flowing into the Amundsen Sea. It is in a remote region that is difficult for humans to access, which is why robotic exploration is necessary.

How warm is the water melting the glacier?

The water is not “hot” by human standards. It is generally 1 to 2 degrees Celsius (around 34-35 degrees Fahrenheit) above the local freezing point. However, because water transfers heat much more efficiently than air, this small temperature difference is enough to cause massive melting when it comes into contact with ice.

Can we stop the melting of Thwaites Glacier?

Geoengineering solutions have been proposed, such as building underwater curtains to block warm water or drilling holes to pump water out. However, most scientists agree these are logistical nightmares due to the scale and remote location. The primary way to slow the process is reducing global carbon emissions to prevent ocean temperatures from rising further.

When will the glacier collapse?

There is no single date. The “collapse” is a process that could span several decades to a few centuries. However, the recent data regarding warm water intrusion suggests the ice shelf could break up significantly within the next 5 to 10 years, which would accelerate the flow of land ice into the sea.