The unquantified mass loss of Northern Hemisphere marine-terminating glaciers from 2000–2020

Abstract

In the Northern Hemisphere, ~1500 glaciers, accounting for 28% of glacierized area outside the Greenland Ice Sheet, terminate in the ocean. Glacier mass loss at their ice-ocean interface, known as frontal ablation, has not yet been comprehensively quantified. Here, we estimate decadal frontal ablation from measurements of ice discharge and terminus position change from 2000 to 2020. We bias-correct and cross-validate estimates and uncertainties using independent sources. Frontal ablation of marine-terminating glaciers contributed an average of 44.47 ± 6.23 Gt a−1 of ice to the ocean from 2000 to 2010, and 51.98 ± 4.62 Gt a−1 from 2010 to 2020. Ice discharge from 2000 to 2020 was equivalent to 2.10 ± 0.22 mm of sea-level rise and comprised approximately 79% of frontal ablation, with the remainder from terminus retreat. Near-coastal areas most impacted include Austfonna, Svalbard, and central Severnaya Zemlya, the Russian Arctic, and a few Alaskan fjords.

Global glacier change in the 21st century: Every increase in temperature matters

“…We produce a set of global glacier projections for every glacier on Earth for SSPs from 2015 to 2100 by leveraging global glacier mass balance data (1) and near-global frontal ablation data (10)(11)(12)(13). To provide policy-relevant scenarios, our projections are grouped based on mean global temperature increases by the end of the 21st century compared with preindustrial levels to explicitly link differences in glacier mass loss, sea level rise, and the number of glaciers that vanish in response to changes in mean global temperature.…”

Advances in data availability to constrain and evaluate frontal ablation of ice-dynamical models of Greenland's tidewater peripheral glaciers

“…There are few estimates of dynamic mass loss for tidewater PGs (Recinos and others, 2021;Bollen and others, 2022;Kochtitzky and others, 2022), but those still suffer from considerable uncertainty associated with the method selected to estimate the ice thickness at the calving front (e.g. Bollen and others, 2022), significant uncertainty in the terminus geometry and errors in the true value of the frontal ablation flux (e.g.…”

“…However, Bollen and others (2022) solid ice discharge estimates do not include mass changes due to terminus retreat or advance during the calculated period (see Enderlin and others, 2014;Bollen and others, 2022, for more information). Kochtitzky and others (2022) address this issue and estimate frontal ablation indirectly, by calculating ice discharge and terminus mass change, while accounting for the climatic mass balance (MB) (i.e. the mass changes due to snow accumulation, surface melt and refreezing) below the flux gate.…”

“…the mass changes due to snow accumulation, surface melt and refreezing) below the flux gate. Yet Kochtitzky and others (2022) estimates are limited to 537 glaciers and there is no observation prior to 2000.…”

“…data that were not used for calibration). All three studies mentioned above (Recinos and others, 2021;Bollen and others, 2022;Kochtitzky and others, 2022), hence represent independent assessments of frontal ablation for tidewater PGs that can be compared and evaluated using new published region-wide data. Here we make use of the ice thickness estimates from Millan and others (2022) to evaluate the ice thickness estimates obtained by OGGM after calibrating the frontal ablation parameterization with the methods described in Recinos and others (2021).…”