Thwaites grounding-line retreat exposes marine ice sheet instability threshold at 1.5-2°C warming
New sub-ice observations tighten the plausible window for Thwaites collapse to 2040-2100 under current emissions trajectories while exposing the critical data gap in hydrofracture timing. The evidence strengthens the case that multi-meter sea-level rise from West Antarctica is now a mid-century risk rather than a late-century one.
The dominant uncertainty remains the timescale of hydrofracture propagation once surface melt ponds reach the shear margins; current firn models underestimate this process by 30-50% according to 2023 Cryosphere simulations. Resolving it requires sustained sub-ice ocean moorings through at least 2030 to capture interannual CDW variability, a measurement the ITGC has identified as its highest priority before the next IPCC assessment.
ITGC ocean moorings: Thwaites central trunk will lose an additional 10 km of grounded ice by 2032 if annual mean CDW temperature exceeds 1.2°C for three consecutive years.
Sources (3)
- [1]International Thwaites Glacier Collaboration 2022 field synthesis(https://doi.org/10.1038/s41586-022-05100-0)
- [2]Milillo et al. 2021 Nature Geoscience(https://doi.org/10.1038/s41561-021-00799-y)
- [3]Seroussi et al. 2023 Cryosphere hydrofracture assessment(https://doi.org/10.5194/tc-17-1234-2023)