Thwaites Glacier May Add 30 mm to Sea Levels by 2100 as New Models Double Forecast
Updated
Updated · Nature.com · Oct 12
Thwaites Glacier May Add 30 mm to Sea Levels by 2100 as New Models Double Forecast
3 articles · Updated · Nature.com · Oct 12
Summary
New observation-constrained simulations put Thwaites Glacier’s sea-level contribution at up to 30 ± 6 mm by 2100—about double earlier projections—even without additional climate warming.
The increase comes from modeling 2–5 km-wide actively melting grounding zones, where seawater intrudes beneath grounded ice; models without that process were four times less likely to match nearly 30 years of observed retreat, thinning and acceleration.
The study says those grounding-zone processes could unpin Thwaites from the stabilizing Mouginot Ridge as early as 2038, allowing continued retreat toward the next seafloor high, South Ridge.
Under a 5 ± 1 km grounding zone consistent with recent satellite observations, projected sea-level rise reaches 30.1 ± 5.7 mm; a 3 ± 1 km zone yields 19.4 ± 5.2 mm, versus 8.3 ± 3.0 mm in models omitting grounding zones.
The findings place Thwaites near the upper end of prior Antarctic model ranges and suggest grounding-zone physics may matter more than moderate ocean warming in narrowing sea-level uncertainty.
If hidden ocean water melts Thwaites Glacier from below, could global coastlines face catastrophic flooding decades earlier than predicted?
With new models doubling Thwaites' sea-level contribution by 2100, are our current global coastal defense strategies already obsolete?
Thwaites Glacier’s 2026 Forecast: Sea Level Rise Now Expected to Double by 2100
Overview
A groundbreaking 2026 study found that Thwaites Glacier could double its projected sea level rise contribution by 2100, due to new modeling that includes dynamic, multi-kilometer grounding zones. Ocean tides drive tidal pumping, pushing warm water deep beneath the glacier and disrupting its insulating layer, which leads to intense melting at the base. This process increases the risk that Thwaites will unpin from Mouginot Ridge, causing rapid retreat down an inward-sloping bed. Such runaway ice loss could destabilize the entire West Antarctic Ice Sheet, raising global sea levels by over 3 meters and threatening major coastal cities worldwide.