Ice-shelf retreat drives recent Pine Island Glacier speedup

Abstract

Speedup of Pine Island Glacier over the past several decades has made it Antarctica’s largest contributor to sea-level rise. The past speedup is largely due to grounding-line retreat in response to ocean-induced thinning that reduced ice-shelf buttressing. While speeds remained fairly steady from 2009 to late 2017, our Copernicus Sentinel 1A/B–derived velocity data show a >12% speedup over the past 3 years, coincident with a 19-km retreat of the ice shelf. We use an ice-flow model to simulate this loss, finding that accelerated calving can explain the recent speedup, independent of the grounding-line, melt-driven processes responsible for past speedups. If the ice shelf’s rapid retreat continues, it could further destabilize the glacier far sooner than would be expected due to surface- or ocean-melting processes.

Ocean-induced melt volume directly paces ice loss from Pine Island Glacier

“…3C ) over the following decade. In actuality, however, ice loss has increased by ~10% since 2017 as the glacier sped up, coincident with a ~20-km shelf-length reduction due to iceberg calving ( 25 ).…”

“…A complete surface melt–induced collapse would yield greater losses ( 30 ), but such an event is unlikely to occur because of surface warming at least through the 21st century ( 31 ). The recent shelf loss appears to be due to mechanical weakening in response to the speedup, and the likelihood that such processes will drive further retreat is unclear ( 25 , 32 ).…”

“…For the period from 2009 to 2017 when speeds were relatively steady ( 25 ), we computed a mean annual thinning of 10 Gt/year using yearly estimates of thickness derived from surface elevation under the assumption of hydrostatic equilibrium. The SD of this estimate is 9 Gt/year, which represents both noise and interannual variability.…”

Analysis of the interannual variability in satellite gravity solutions: detection of climate modes fingerprints in water mass displacements across continents and oceans

“…Paolo et al 2018) and may by extension impact grounded ice (e.g. Joughin et al 2021). This is further discussed in Sect.…”

“…ocean warming, grounding line retreat) (e.g. Joughin et al 2021). Besides, the mass balance of inland glaciers is also impacted by precipitation, that has been shown to contain intermittent ENSO and strong SAM signatures (e.g.…”