1
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Schmidt BE, Washam P, Davis PED, Nicholls KW, Holland DM, Lawrence JD, Riverman KL, Smith JA, Spears A, Dichek DJG, Mullen AD, Clyne E, Yeager B, Anker P, Meister MR, Hurwitz BC, Quartini ES, Bryson FE, Basinski-Ferris A, Thomas C, Wake J, Vaughan DG, Anandakrishnan S, Rignot E, Paden J, Makinson K. Publisher Correction: Heterogeneous melting near the Thwaites Glacier grounding line. Nature 2023; 615:E21. [PMID: 36829047 PMCID: PMC10017506 DOI: 10.1038/s41586-023-05861-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Affiliation(s)
- B E Schmidt
- Department of Astronomy, Cornell University, Ithaca, NY, USA. .,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA.
| | - P Washam
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | | | | | - D M Holland
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA.,Center for Global Sea Level Change, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - J D Lawrence
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - K L Riverman
- Department of Environmental Studies, University of Portland, Portland, OR, USA
| | - J A Smith
- British Antarctic Survey, Cambridge, UK
| | - A Spears
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - D J G Dichek
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - A D Mullen
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - E Clyne
- Department of Geosciences, Pennsylvania State University, State College, PA, USA.,Environmental Studies, Lewis & Clark College, Portland, OR, USA
| | - B Yeager
- Center for Global Sea Level Change, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - P Anker
- British Antarctic Survey, Cambridge, UK
| | - M R Meister
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - B C Hurwitz
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - E S Quartini
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - F E Bryson
- Department of Astronomy, Cornell University, Ithaca, NY, USA.,Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA.,School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - A Basinski-Ferris
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - C Thomas
- British Antarctic Survey, Cambridge, UK
| | - J Wake
- British Antarctic Survey, Cambridge, UK
| | | | - S Anandakrishnan
- Department of Geosciences, Pennsylvania State University, State College, PA, USA
| | - E Rignot
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - J Paden
- Center for Remote Sensing and Integrated Systems, University of Kansas, Lawrence, KS, USA
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2
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Schmidt BE, Washam P, Davis PED, Nicholls KW, Holland DM, Lawrence JD, Riverman KL, Smith JA, Spears A, Dichek DJG, Mullen AD, Clyne E, Yeager B, Anker P, Meister MR, Hurwitz BC, Quartini ES, Bryson FE, Basinski-Ferris A, Thomas C, Wake J, Vaughan DG, Anandakrishnan S, Rignot E, Paden J, Makinson K. Heterogeneous melting near the Thwaites Glacier grounding line. Nature 2023; 614:471-478. [PMID: 36792738 PMCID: PMC9931587 DOI: 10.1038/s41586-022-05691-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 12/22/2022] [Indexed: 02/17/2023]
Abstract
Thwaites Glacier represents 15% of the ice discharge from the West Antarctic Ice Sheet and influences a wider catchment1-3. Because it is grounded below sea level4,5, Thwaites Glacier is thought to be susceptible to runaway retreat triggered at the grounding line (GL) at which the glacier reaches the ocean6,7. Recent ice-flow acceleration2,8 and retreat of the ice front8-10 and GL11,12 indicate that ice loss will continue. The relative impacts of mechanisms underlying recent retreat are however uncertain. Here we show sustained GL retreat from at least 2011 to 2020 and resolve mechanisms of ice-shelf melt at the submetre scale. Our conclusions are based on observations of the Thwaites Eastern Ice Shelf (TEIS) from an underwater vehicle, extending from the GL to 3 km oceanward and from the ice-ocean interface to the sea floor. These observations show a rough ice base above a sea floor sloping upward towards the GL and an ocean cavity in which the warmest water exceeds 2 °C above freezing. Data closest to the ice base show that enhanced melting occurs along sloped surfaces that initiate near the GL and evolve into steep-sided terraces. This pronounced melting along steep ice faces, including in crevasses, produces stratification that suppresses melt along flat interfaces. These data imply that slope-dependent melting sculpts the ice base and acts as an important response to ocean warming.
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Affiliation(s)
- B E Schmidt
- Department of Astronomy, Cornell University, Ithaca, NY, USA.
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA.
| | - P Washam
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | | | | | - D M Holland
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
- Center for Global Sea Level Change, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - J D Lawrence
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - K L Riverman
- Department of Environmental Studies, University of Portland, Portland, OR, USA
| | - J A Smith
- British Antarctic Survey, Cambridge, UK
| | - A Spears
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - D J G Dichek
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - A D Mullen
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - E Clyne
- Department of Geosciences, Pennsylvania State University, State College, PA, USA
- Environmental Studies, Lewis & Clark College, Portland, OR, USA
| | - B Yeager
- Center for Global Sea Level Change, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - P Anker
- British Antarctic Survey, Cambridge, UK
| | - M R Meister
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - B C Hurwitz
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - E S Quartini
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
| | - F E Bryson
- Department of Astronomy, Cornell University, Ithaca, NY, USA
- Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - A Basinski-Ferris
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - C Thomas
- British Antarctic Survey, Cambridge, UK
| | - J Wake
- British Antarctic Survey, Cambridge, UK
| | | | - S Anandakrishnan
- Department of Geosciences, Pennsylvania State University, State College, PA, USA
| | - E Rignot
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - J Paden
- Center for Remote Sensing and Integrated Systems, University of Kansas, Lawrence, KS, USA
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3
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Milillo P, Rignot E, Rizzoli P, Scheuchl B, Mouginot J, Bueso-Bello J, Prats-Iraola P. Heterogeneous retreat and ice melt of Thwaites Glacier, West Antarctica. Sci Adv 2019; 5:eaau3433. [PMID: 30729155 PMCID: PMC6353628 DOI: 10.1126/sciadv.aau3433] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 12/13/2018] [Indexed: 06/02/2023]
Abstract
The glaciers flowing into the Amundsen Sea Embayment, West Antarctica, have undergone acceleration and grounding line retreat over the past few decades that may yield an irreversible mass loss. Using a constellation of satellites, we detect the evolution of ice velocity, ice thinning, and grounding line retreat of Thwaites Glacier from 1992 to 2017. The results reveal a complex pattern of retreat and ice melt, with sectors retreating at 0.8 km/year and floating ice melting at 200 m/year, while others retreat at 0.3 km/year with ice melting 10 times slower. We interpret the results in terms of buoyancy/slope-driven seawater intrusion along preferential channels at tidal frequencies leading to more efficient melt in newly formed cavities. Such complexities in ice-ocean interaction are not currently represented in coupled ice sheet/ocean models.
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Affiliation(s)
- P. Milillo
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - E. Rignot
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - P. Rizzoli
- German Aerospace Center (DLR), Microwaves and Radar Institute, Munich, Germany
| | - B. Scheuchl
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
| | - J. Mouginot
- Department of Earth System Science, University of California, Irvine, Irvine, CA, USA
- Université Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, 38000 Grenoble, France
| | - J. Bueso-Bello
- German Aerospace Center (DLR), Microwaves and Radar Institute, Munich, Germany
| | - P. Prats-Iraola
- German Aerospace Center (DLR), Microwaves and Radar Institute, Munich, Germany
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4
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An L, Rignot E, Mouginot J, Millan R. A Century of Stability of Avannarleq and Kujalleq Glaciers, West Greenland, Explained Using High-Resolution Airborne Gravity and Other Data. Geophys Res Lett 2018; 45:3156-3163. [PMID: 29937605 PMCID: PMC5993245 DOI: 10.1002/2018gl077204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 02/09/2018] [Indexed: 06/08/2023]
Abstract
The evolution of Greenland glaciers in a warming climate depends on their depth below sea level, flow speed, surface melt, and ocean-induced undercutting at the calving front. We present an innovative mapping of bed topography in the frontal regions of Sermeq Avannarleq and Kujalleq, two major glaciers flowing into the ice-choked Torssukatak Fjord, central west Greenland. The mapping combines a mass conservation algorithm inland, multibeam echo sounding data in the fjord, and high-resolution airborne gravity data at the ice-ocean transition where other approaches have traditionally failed. We obtain a reliable, precision (±40 m) solution for bed topography across the ice-ocean boundary. The results reveal a 700 m deep fjord that abruptly ends on a 100-300 m deep sill along the calving fronts. The shallow sills explain the presence of stranded icebergs, the resilience of the glaciers to ocean-induced undercutting by warm Atlantic water, and their remarkable stability over the past century.
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Affiliation(s)
- L. An
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - E. Rignot
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - J. Mouginot
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - R. Millan
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
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5
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Millan R, Rignot E, Mouginot J, Wood M, Bjørk AA, Morlighem M. Vulnerability of Southeast Greenland Glaciers to Warm Atlantic Water From Operation IceBridge and Ocean Melting Greenland Data. Geophys Res Lett 2018; 45:2688-2696. [PMID: 29937604 PMCID: PMC5993238 DOI: 10.1002/2017gl076561] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 02/14/2018] [Accepted: 02/18/2018] [Indexed: 05/02/2023]
Abstract
We employ National Aeronautics and Space Administration (NASA)'s Operation IceBridge high-resolution airborne gravity from 2016, NASA's Ocean Melting Greenland bathymetry from 2015, ice thickness from Operation IceBridge from 2010 to 2015, and BedMachine v3 to analyze 20 major southeast Greenland glaciers. The results reveal glacial fjords several hundreds of meters deeper than previously thought; the full extent of the marine-based portions of the glaciers; deep troughs enabling warm, salty Atlantic Water (AW) to reach the glacier fronts and melt them from below; and few shallow sills that limit the access of AW. The new oceanographic and topographic data help to fully resolve the complex pattern of historical ice front positions from the 1930s to 2017: glaciers exposed to AW and resting on retrograde beds have retreated rapidly, while glaciers perched on shallow sills or standing in colder waters or with major sills in the fjords have remained stable.
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Affiliation(s)
- R. Millan
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - E. Rignot
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
- Jet Propulsion LaboratoryCaltechPasadenaCAUSA
| | - J. Mouginot
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - M. Wood
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
| | - A. A. Bjørk
- Centre for GeoGenetics, Natural History Museum of DenmarkUniversity of CopenhagenCopenhagenDenmark
| | - M. Morlighem
- Department Earth System ScienceUniversity of California IrvineIrvineCAUSA
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6
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Morlighem M, Williams CN, Rignot E, An L, Arndt JE, Bamber JL, Catania G, Chauché N, Dowdeswell JA, Dorschel B, Fenty I, Hogan K, Howat I, Hubbard A, Jakobsson M, Jordan TM, Kjeldsen KK, Millan R, Mayer L, Mouginot J, Noël BPY, O'Cofaigh C, Palmer S, Rysgaard S, Seroussi H, Siegert MJ, Slabon P, Straneo F, van den Broeke MR, Weinrebe W, Wood M, Zinglersen KB. BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation. Geophys Res Lett 2017; 44:11051-11061. [PMID: 29263561 PMCID: PMC5726375 DOI: 10.1002/2017gl074954] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 05/11/2023]
Abstract
Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics, and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation approach. A new 150 m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous data sets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals that the total sea level potential of the Greenland ice sheet is 7.42 ± 0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.
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Affiliation(s)
- M. Morlighem
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - C. N. Williams
- Bristol Glaciology Centre, School of Geographical SciencesUniversity of BristolBristolUK
- Now at British Geological SurveyNottinghamUK
| | - E. Rignot
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - L. An
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - J. E. Arndt
- Alfred‐Wegener‐Institute, Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany
| | - J. L. Bamber
- Bristol Glaciology Centre, School of Geographical SciencesUniversity of BristolBristolUK
| | - G. Catania
- Institute of GeophysicsUniversity of Texas at AustinAustinTXUSA
| | - N. Chauché
- Department of Geography and Earth ScienceAberystwyth UniversityAberystwythUK
| | - J. A. Dowdeswell
- Scott Polar Research InstituteUniversity of CambridgeCambridgeUK
| | - B. Dorschel
- Alfred‐Wegener‐Institute, Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany
| | - I. Fenty
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - K. Hogan
- British Antarctic SurveyNatural Environment Research CouncilCambridgeUK
| | - I. Howat
- Byrd Polar and Climate Research CenterOhio State UniversityColumbusOHUSA
| | - A. Hubbard
- Department of Geography and Earth ScienceAberystwyth UniversityAberystwythUK
- Centre for Arctic Gas Hydrate, Environment and Climate, Department of GeosciencesUiT The Arctic University of NorwayTromsøNorway
| | - M. Jakobsson
- Department of Geology and GeochemistryStockholm UniversityStockholmSweden
| | - T. M. Jordan
- Bristol Glaciology Centre, School of Geographical SciencesUniversity of BristolBristolUK
| | - K. K. Kjeldsen
- Centre for GeoGenetics, Natural History Museum of DenmarkUniversity of CopenhagenCopenhagenDenmark
- Department of Earth SciencesUniversity of OttawaOttawaOntarioCanada
- Department of Geodesy, DTU Space, National Space InstituteTechnical University of DenmarkKongens LyngbyDenmark
| | - R. Millan
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - L. Mayer
- Center for Coastal and Ocean MappingUniversity of New HampshireDurhamNHUSA
| | - J. Mouginot
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
| | - B. P. Y. Noël
- Institute for Marine and Atmospheric Research UtrechtUtrecht UniversityUtrechtNetherlands
| | - C. O'Cofaigh
- Department of GeographyDurham UniversityDurhamUK
| | - S. Palmer
- College of Life and Environmental SciencesUniversity of ExeterExeterUK
| | - S. Rysgaard
- Centre for Earth Observation Science, Department of Environment and GeographyUniversity of ManitobaWinnipegManitobaCanada
- Greenland Institute of Natural ResourcesNuukGreenland
- Arctic Research CentreAarhus UniversityAarhusDenmark
| | - H. Seroussi
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | - M. J. Siegert
- Grantham Institute and Department of Earth Science and EngineeringImperial College LondonLondonUK
| | - P. Slabon
- Alfred‐Wegener‐Institute, Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany
| | - F. Straneo
- Department of Physical OceanographyWoods Hole Oceanographic InstitutionWoods HoleMAUSA
| | - M. R. van den Broeke
- Institute for Marine and Atmospheric Research UtrechtUtrecht UniversityUtrechtNetherlands
| | - W. Weinrebe
- Alfred‐Wegener‐Institute, Helmholtz Centre for Polar and Marine ResearchBremerhavenGermany
| | - M. Wood
- Department of Earth System ScienceUniversity of CaliforniaIrvineCAUSA
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7
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Mouginot J, Rignot E, Scheuchl B, Fenty I, Khazendar A, Morlighem M, Buzzi A, Paden J. Fast retreat of Zachariæ Isstrøm, northeast Greenland. Science 2015; 350:1357-61. [PMID: 26563135 DOI: 10.1126/science.aac7111] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 10/28/2015] [Indexed: 11/02/2022]
Abstract
After 8 years of decay of its ice shelf, Zachariæ Isstrøm, a major glacier of northeast Greenland that holds a 0.5-meter sea-level rise equivalent, entered a phase of accelerated retreat in fall 2012. The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. Its equal-ice-volume neighbor, Nioghalvfjerdsfjorden, is also melting rapidly but retreating slowly along an upward-sloping bed. The destabilization of this marine-based sector will increase sea-level rise from the Greenland Ice Sheet for decades to come.
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Affiliation(s)
- J Mouginot
- Department of Earth System Science, University of California, Irvine, CA 92697, USA.
| | - E Rignot
- Department of Earth System Science, University of California, Irvine, CA 92697, USA. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - B Scheuchl
- Department of Earth System Science, University of California, Irvine, CA 92697, USA
| | - I Fenty
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - A Khazendar
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA
| | - M Morlighem
- Department of Earth System Science, University of California, Irvine, CA 92697, USA
| | - A Buzzi
- Department of Earth System Science, University of California, Irvine, CA 92697, USA
| | - J Paden
- Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, KS 66045, USA
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8
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Khazendar A, Schodlok MP, Fenty I, Ligtenberg SRM, Rignot E, van den Broeke MR. Observed thinning of Totten Glacier is linked to coastal polynya variability. Nat Commun 2014; 4:2857. [PMID: 24305466 DOI: 10.1038/ncomms3857] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 11/01/2013] [Indexed: 11/09/2022] Open
Abstract
Analysis of ICESat-1 data (2003-2008) shows significant surface lowering of Totten Glacier, the glacier discharging the largest volume of ice in East Antarctica, and less change on nearby Moscow University Glacier. After accounting for firn compaction anomalies, the thinning appears to coincide with fast-flowing ice indicating a dynamical origin. Here, to elucidate these observations, we apply high-resolution ice-ocean modelling. Totten Ice Shelf is simulated to have higher, more variable basal melting rates. We link this variability to the volume of cold water, originating in polynyas upon sea ice formation, reaching the sub-ice-shelf cavity. Hence, we propose that the observed increased thinning of Totten Glacier is due to enhanced basal melting caused by a decrease in cold polynya water reaching its cavity. We support this hypothesis with passive microwave data of polynya extent variability. Considering the widespread changes in sea ice conditions, this mechanism could be contributing extensively to ice-shelf instability.
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Affiliation(s)
- A Khazendar
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
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9
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Abstract
We compare the volume flux divergence of Antarctic ice shelves in 2007 and 2008 with 1979 to 2010 surface accumulation and 2003 to 2008 thinning to determine their rates of melting and mass balance. Basal melt of 1325 ± 235 gigatons per year (Gt/year) exceeds a calving flux of 1089 ± 139 Gt/year, making ice-shelf melting the largest ablation process in Antarctica. The giant cold-cavity Ross, Filchner, and Ronne ice shelves covering two-thirds of the total ice-shelf area account for only 15% of net melting. Half of the meltwater comes from 10 small, warm-cavity Southeast Pacific ice shelves occupying 8% of the area. A similar high melt/area ratio is found for six East Antarctic ice shelves, implying undocumented strong ocean thermal forcing on their deep grounding lines.
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Affiliation(s)
- E Rignot
- Department of Earth System Science, University of California, Irvine, CA 92697, USA.
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Larour E, Schiermeier J, Rignot E, Seroussi H, Morlighem M, Paden J. Sensitivity Analysis of Pine Island Glacier ice flow using ISSM and DAKOTA. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jf002146] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Larour E, Seroussi H, Morlighem M, Rignot E. Continental scale, high order, high spatial resolution, ice sheet modeling using the Ice Sheet System Model (ISSM). ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jf002140] [Citation(s) in RCA: 255] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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13
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Kavanaugh JL, Cuffey KM, Morse DL, Conway H, Rignot E. Dynamics and mass balance of Taylor Glacier, Antarctica: 1. Geometry and surface velocities. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2009jf001309] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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14
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Khazendar A, Rignot E, Larour E. Roles of marine ice, rheology, and fracture in the flow and stability of the Brunt/Stancomb-Wills Ice Shelf. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jf001124] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Thomas R, Rignot E, Casassa G, Kanagaratnam P, Acuña C, Akins T, Brecher H, Frederick E, Gogineni P, Krabill W, Manizade S, Ramamoorthy H, Rivera A, Russell R, Sonntag J, Swift R, Yungel J, Zwally J. Accelerated sea-level rise from West Antarctica. Science 2004; 306:255-8. [PMID: 15388895 DOI: 10.1126/science.1099650] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent aircraft and satellite laser altimeter surveys of the Amundsen Sea sector of West Antarctica show that local glaciers are discharging about 250 cubic kilometers of ice per year to the ocean, almost 60% more than is accumulated within their catchment basins. This discharge is sufficient to raise sea level by more than 0.2 millimeters per year. Glacier thinning rates near the coast during 2002-2003 are much larger than those observed during the 1990s. Most of these glaciers flow into floating ice shelves over bedrock up to hundreds of meters deeper than previous estimates, providing exit routes for ice from further inland if ice-sheet collapse is under way.
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Affiliation(s)
- R Thomas
- EG&G Inc., NASA Goddard Space Flight Center (GSFC)/Wallops Flight Facility (WFF), Building N-159, Wallops Island, VA 23337, USA.
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Abstract
A statistical image model is proposed for segmenting polarimetric synthetic aperture radar (SAR) data into regions of homogeneous and similar polarimetric backscatter characteristics. A model for the conditional distribution of the polarimetric complex data is combined with a Markov random field representation for the distribution of the region labels to obtain the posterior distribution. Optimal region labeling of the data is then defined as maximizing the posterior distribution of the region labels given the polarimetric SAR complex data (maximum a posteriori (MAP) estimate). Two procedures for selecting the characteristics of the regions are then discussed. Results using real multilook polarimetric SAR complex data are given to illustrate the potential of the two selection procedures and evaluate the performance of the MAP segmentation technique. It is also shown that dual polarization SAR data can yield segmentation resultS similar to those obtained with fully polarimetric SAR data.
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Affiliation(s)
- E Rignot
- Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA
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Drinkwater MR, Kwok R, Winebrenner DP, Rignot E. Multifrequency polarimetric synthetic aperture radar observations of sea ice. ACTA ACUST UNITED AC 1991. [DOI: 10.1029/91jc01915] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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