Humboldt Glacier, Northern Greenland, is Likely to Contribute Twice as Much to 21st Century Sea Level Rise as Previously Thought
An ensemble of calibrated numerical model simulations shows that Humboldt Glacier — one of the largest outlet glaciers of the Greenland Ice Sheet — has the potential to contribute significantly to global sea-level rise by 2100. While all simulations suggest >5 mm of global sea-level increase from Humboldt Glacier, different assumptions about the physics of ice sliding and iceberg calving predict a likely range of up to 8.7 mm, with larger contributions possible.
Our results show that calibration of sliding and calving parameters to reproduce historical changes is crucial to predicting the future evolution of outlet glaciers of the Greenland Ice Sheet. Previous studies using uncalibrated sliding parameters predict half as much sea-level contribution from Humboldt Glacier as we predict in this study.
Humboldt Glacier, northern Greenland, contains ice equivalent to 19 cm of global sea level, yet its likely future contribution to sea-level rise has previously been shown to be modest. However, its recent acceleration during ocean-forced retreat events suggests that previous projections might underestimate its potential sea-level contribution. We calibrated a numerical ice-sheet model against recent observations and performed an ensemble of projections to 2100 forced by simulation data from state-of-the-art global climate models. We show that Humboldt Glacier is likely to contribute twice as much to global sea level as previously predicted. Our simulations predict between 5.2 and 8.7 mm sea-level rise from Humboldt Glacier by 2100, with larger contributions up to ~12 mm not ruled out. This is a significant fraction of the 90 ± 50 mm sea-level contribution from the entire Greenland Ice Sheet predicted by a recent international multi-model ensemble.