Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica

Milillo, Pietro; Rignot, Eric; Rizzoli, Paola; Scheuchl, B.; Mouginot, J.; Bueso-Bello, José-Luis; Prats-Iraola, Pau

doi:10.1126/sciadv.aau3433

Cited by 167 publications

(257 citation statements)

References 33 publications

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“…Satellite and airborne InSAR provide millimeter‐ to centimeter‐scale measurements of surface deformation and have been used to quantify the ground surface deformation associated with landslides (e.g., Bayer et al, ; Hu et al, ; Schlögel et al, ), faults (e.g., Fielding et al, ; Fialko et al, ; Huang et al, ), glaciers (e.g., Gourmelen et al, ; Milillo et al, ), and ground subsidence (e.g., Bekaert et al, ; Chaussard et al, ; Murray & Lohman, ). Previous studies have used satellite‐based InSAR to identify and monitor slow‐moving landslides in the California Coast Ranges (Cohen‐Waeber et al, ; Handwerger et al, , , ; Hilley et al, ; Roering et al, , ; Zhao et al, ).…”

Section: Methodsmentioning

confidence: 99%

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

et al. 2019

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Episodically to continuously active slow-moving landslides are driven by precipitation.Climate change, which is altering both the frequency and magnitude of precipitation worldwide, is therefore predicted to have a major impact on landslides. Here we examine the behavior of hundreds of slow-moving landslides in northern California in response to large changes in annual precipitation that occurred between 2016 and 2018. We quantify the landslide displacement using repeat-pass radar interferometry and pixel offset tracking techniques on a novel data set from the airborne NASA/JPL Uninhabited Aerial Vehicle Synthetic Aperture Radar. We found that 312 landslides were moving due to extreme rainfall during 2017, compared to 119 during 2016, which was the final year of a historic multiyear drought. However, with a return to below to average rainfall in 2018, only 146 landslides remained in motion. The increased number of landslides during 2017 was primarily accommodated by landslides that were smaller than the landslides that remained active between 2016 and 2018. Furthermore, by examining a subset of 51 landslides, we found that 49 had increased velocities during 2017 when compared to 2016. Our results show that slow-moving landslides are sensitive to large changes in annual precipitation, particularly the smaller and thinner landslides that likely experience larger basal pore-water pressure changes. Based on climate model predictions for the next century in California, which include increases in average annual precipitation and increases in the frequency of dry-to-wet extremes, we hypothesize that there will be an overall increase in landslide activity.

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Section: Methodsmentioning

confidence: 99%

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

et al. 2019

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“…At present, the grounding line may even be engaged in an unstable retreat down the retrograde bedrock slope on which Pine Island Glacier is grounded (Favier et al, 2014;Jenkins et al, 2016). Elsewhere, grounding line retreat on Thwaites Glacier is driving more efficient basal melting (Milillo et al, 2019) and an acceleration in the rate of mass loss from the Amundsen Sea region (IMBIE, 2018).…”

Section: Introductionmentioning

confidence: 99%

Turbulence Observations Beneath Larsen C Ice Shelf, Antarctica

Davis

Nicholls

2019

JGR Oceans

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Increased ocean‐driven basal melting beneath Antarctic ice shelves causes grounded ice to flow into the ocean at an accelerated rate, with consequences for global sea level. The turbulent transfer of heat through the ice shelf‐ocean boundary layer is critical in setting the basal melt rate, yet the processes controlling this transfer are poorly understood and inadequately represented in global climate models. This creates large uncertainties in predictions of future sea level rise. Using a hot‐water drilled access hole, two turbulence instrument clusters (TICs) were deployed 2.5 and 13.5 m beneath Larsen C ice shelf in December 2011. Both instruments returned a yearlong record of turbulent velocity fluctuations, providing a unique opportunity to explore the turbulent processes within the ice shelf‐ocean boundary layer. Although the scaling between the turbulent kinetic energy (TKE) dissipation rate and mean flow speed varies with distance from the ice shelf base, at both TICs the TKE dissipation rate is balanced entirely by the rate of shear production. The freshwater released by basal melting plays no role in the TKE balance. When the upper TIC is within the log‐layer, we derive an under‐ice drag coefficient of 0.0022 and a roughness length of 0.44 mm, indicating that the ice base is smooth. Finally, we demonstrate that although the canonical three‐equation melt rate parameterization can accurately predict the melt rate for this example of smooth ice underlain by a cold, tidally forced boundary layer, the law of the wall assumption employed by the parameterization does not hold at low flow speeds.

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“…The glacier moves at a speed up to 4 km/year and is 120 km wide (Figure a). In the main trunk, the grounding line retreated 14 km from 1996 to 2011 (Rignot et al, ) and this rate has continued up to present (Milillo et al, ). In 2014, the glacier discharged 126 Gt of ice into the ocean, which was 50 Gt in excess of what is required to maintain mass equilibrium with the accumulation of snowfall, a doubling in loss from 28 Gt/year in 2006 (Medley et al, ; Mouginot et al, ).…”

Section: Introductionmentioning

confidence: 99%

Impact of Iceberg Calving on the Retreat of Thwaites Glacier, West Antarctica Over the Next Century With Different Calving Laws and Ocean Thermal Forcing

Rignot

Seroussi

et al. 2019

Geophysical Research Letters

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Thwaites Glacier, West Antarctica, has been a major contributor to global sea level rise over the past decades. Prior studies illustrated the critical role of ice shelf melt and iceberg calving based on cliff height in driving the retreat of Thwaites glacier. Here, we simulate its evolution with various calving laws and rates of frontal melt by the ocean in the absence of a buttressing ice shelf. Over the next century, we find that volume losses increase by 15-160% with a von Mises calving law compared to the case where the initial ice shelf is kept and the ice front is fixed at its current position, 10-20% with a buoyancy-driven calving law, and 5-50% with frontal melt caused by ocean thermal forcing. Bed topography exerts the ultimate control on the evolution of Thwaites. In all simulations, once Thwaites Glacier retreats past the western subglacial ridge, the retreat becomes rapidly unstoppable.

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Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica

Abstract: The heterogeneous retreat of Thwaites glacier indicates complexities of ice melt processes taking place at the grounding zone.

Cited by 167 publications

References 33 publications

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

Widespread Initiation, Reactivation, and Acceleration of Landslides in the Northern California Coast Ranges due to Extreme Rainfall

Turbulence Observations Beneath Larsen C Ice Shelf, Antarctica

Impact of Iceberg Calving on the Retreat of Thwaites Glacier, West Antarctica Over the Next Century With Different Calving Laws and Ocean Thermal Forcing

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