Thwaites Glacier in West Antarctica is losing ice at an accelerated pace, with a new modeling study published in Nature Communications showing that warm seawater is penetrating deeper beneath the ice shelf and doubling its projected contribution to global sea-level rise by the year 2100.
Thwaites Glacier Tidal Pumping Accelerates Ice Melt
Researchers from the University of California, Irvine, and NASA Jet Propulsion Laboratory developed a detailed model focusing on the grounding zone, where ice resting on bedrock begins to float. The study found that a mechanism known as tidal pumping allows relatively warm seawater to reach several kilometers further beneath the glacier.
While previous conventional ice sheet models treated grounding lines as fixed boundaries, this new simulation accounts for tidal movements that repeatedly lift and lower the ice shelf. Without assuming any additional atmospheric warming beyond current conditions, the increased intrusion of warm water means Thwaites could contribute up to 30 millimeters, or roughly 1.2 inches, to global sea-level rise by 2100. That figure marks a twofold increase over earlier standard projections of about 15 millimeters or 0.6 inches. The results add to concerns over coastal flood risks, even though that figure is not a projection of total global sea-level rise. Mattia Poinelli, a project scientist at the University of California, Los Angeles (UCLA) and lead author of the study, explained that this mechanism had not been fully accounted for in a number of ice sheet change models. The research was published on October 12.
Mouginot Ridge Retention Structure Faces High Risk of Detachment
Located in one of the most remote places on Earth, the glacier has been shrinking continuously for decades. Since 2000, the glacier has shed vast amounts of ice, losing mass annually, and currently accounting for about 4 percent of global sea-level rise. Alongside other glaciers including Pine Island Glacier, Thwaites serves to hold back a massive flow of ice from land toward the sea. The seafloor beneath Thwaites slopes downward toward the interior of the continent, exposing more ice to warm seawater as the glacier retreats.
The new simulations indicate a 60 percent probability that Thwaites will lose contact with the Mouginot Ridge—an underwater structural barrier currently helping to hold back the glacier’s flow—by 2100, with detachment potentially occurring as early as the late 2030s. Two underwater ridges still function to restrain ice movement, including Mouginot Ridge. Eric Rignot, a professor of Earth system science at the University of California, Irvine, emphasized that while reducing greenhouse gas emissions remains critical, the planet may still face unavoidable sea-level increases driven by damage already sustained.
The world’s largest glacier, Thwaites Glacier in West Antarctica, is melting much faster and could contribute twice as much to global sea level rise over the next century as previously expected.Here's what we know: https://t.co/ewJNrFRWC3 pic.twitter.com/nWIDVPTi3g
Frequently Asked Questions About Thwaites Glacier Melt
How much global sea-level rise would occur if Thwaites Glacier collapses entirely?
If the entire glacier melts, it holds enough ice to raise global sea levels by more than 60 centimeters. Because Thwaites acts as a natural buttress for the wider West Antarctic Ice Sheet, its complete collapse could trigger a domino effect raising global oceans by roughly 3 meters.
What are scientists planning next to measure sub-glacial melting?
Researchers plan to conduct direct field observations in the Thwaites region by 2028, deploying specialized instruments beneath the ice shelf to record seawater movement and refine future sea-level projections.
Thwaites Glacier in West Antarctica, the planet's widest and most unpredictable glacier, is melting "more aggressively" than previously projected, meaning its impacts on global sea level rise could be double current estimates. https://t.co/AtsKwZBd7x pic.twitter.com/xpt7YUsaT5
Did you know? Thwaites Glacier covers approximately 192,000 square kilometers, making it roughly the size of the US state of Florida, and features towering ice cliffs as documented by the British Antarctic Survey.
“We have been aware of the impact of climate change on the planet’s sensitive ice sheets for decades, but in recent years, growing awareness of what is actually happening beneath the surface of glaciers like Thwaites has made us increasingly concerned,” Eric Rignot said.
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