1
|
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. GEOPHYSICAL RESEARCH LETTERS 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] [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.
Collapse
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
| |
Collapse
|
2
|
Tedstone AJ, Nienow PW, Gourmelen N, Dehecq A, Goldberg D, Hanna E. Decadal slowdown of a land-terminating sector of the Greenland Ice Sheet despite warming. Nature 2016; 526:692-5. [PMID: 26511580 DOI: 10.1038/nature15722] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 09/01/2015] [Indexed: 11/09/2022]
Abstract
Ice flow along land-terminating margins of the Greenland Ice Sheet (GIS) varies considerably in response to fluctuating inputs of surface meltwater to the bed of the ice sheet. Such inputs lubricate the ice-bed interface, transiently speeding up the flow of ice. Greater melting results in faster ice motion during summer, but slower motion over the subsequent winter, owing to the evolution of an efficient drainage system that enables water to drain from regions of the ice-sheet bed that have a high basal water pressure. However, the impact of hydrodynamic coupling on ice motion over decadal timescales remains poorly constrained. Here we show that annual ice motion across an 8,000-km(2) land-terminating region of the west GIS margin, extending to 1,100 m above sea level, was 12% slower in 2007-14 compared with 1985-94, despite a 50% increase in surface meltwater production. Our findings suggest that, over these three decades, hydrodynamic coupling in this section of the ablation zone resulted in a net slowdown of ice motion (not a speed-up, as previously postulated). Increases in meltwater production from projected climate warming may therefore further reduce the motion of land-terminating margins of the GIS. Our findings suggest that these sectors of the ice sheet are more resilient to the dynamic impacts of enhanced meltwater production than previously thought.
Collapse
Affiliation(s)
- Andrew J Tedstone
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Peter W Nienow
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Noel Gourmelen
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Amaury Dehecq
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK.,Université Savoie Mont-Blanc, Polytech Annecy-Chambéry, LISTIC, BP 80439, 74944 Annecy-le-Vieux cedex, France
| | - Daniel Goldberg
- School of GeoSciences, University of Edinburgh, Edinburgh EH8 9XP, UK
| | - Edward Hanna
- Department of Geography, University of Sheffield, Sheffield S10 2TN, UK
| |
Collapse
|
3
|
Khan SA, Aschwanden A, Bjørk AA, Wahr J, Kjeldsen KK, Kjær KH. Greenland ice sheet mass balance: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2015; 78:046801. [PMID: 25811969 DOI: 10.1088/0034-4885/78/4/046801] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs and gravimetry data sets together with modelling studies. We revisit the mass loss of different sectors and show that they manifest quite different sensitivities to atmospheric and oceanic forcing. In addition, we discuss recent progress in constructing coupled ice-ocean-atmosphere models required to project realistic future sea-level changes.
Collapse
Affiliation(s)
- Shfaqat A Khan
- DTU Space-National Space Institute, Technical University of Denmark, Department of Geodesy, Kgs. Lyngby, Denmark
| | | | | | | | | | | |
Collapse
|
4
|
Comiso JC, Hall DK. Climate trends in the Arctic as observed from space. WILEY INTERDISCIPLINARY REVIEWS. CLIMATE CHANGE 2014; 5:389-409. [PMID: 25810765 PMCID: PMC4368101 DOI: 10.1002/wcc.277] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The Arctic is a region in transformation. Warming in the region has been amplified, as expected from ice-albedo feedback effects, with the rate of warming observed to be ∼0.60 ± 0.07°C/decade in the Arctic (>64°N) compared to ∼0.17°C/decade globally during the last three decades. This increase in surface temperature is manifested in all components of the cryosphere. In particular, the sea ice extent has been declining at the rate of ∼3.8%/decade, whereas the perennial ice (represented by summer ice minimum) is declining at a much greater rate of ∼11.5%/decade. Spring snow cover has also been observed to be declining by -2.12%/decade for the period 1967-2012. The Greenland ice sheet has been losing mass at the rate of ∼34.0 Gt/year (sea level equivalence of 0.09 mm/year) during the period from 1992 to 2011, but for the period 2002-2011, a higher rate of mass loss of ∼215 Gt/year has been observed. Also, the mass of glaciers worldwide declined at the rate of 226 Gt/year from 1971 to 2009 and 275 Gt/year from 1993 to 2009. Increases in permafrost temperature have also been measured in many parts of the Northern Hemisphere while a thickening of the active layer that overlies permafrost and a thinning of seasonally frozen ground has also been reported. To gain insight into these changes, comparative analysis with trends in clouds, albedo, and the Arctic Oscillation is also presented. How to cite this article:WIREs Clim Change 2014, 5:389�409. doi: 10.1002/wcc.277.
Collapse
|
5
|
Shepherd A, Ivins ER, A G, Barletta VR, Bentley MJ, Bettadpur S, Briggs KH, Bromwich DH, Forsberg R, Galin N, Horwath M, Jacobs S, Joughin I, King MA, Lenaerts JTM, Li J, Ligtenberg SRM, Luckman A, Luthcke SB, McMillan M, Meister R, Milne G, Mouginot J, Muir A, Nicolas JP, Paden J, Payne AJ, Pritchard H, Rignot E, Rott H, Sørensen LS, Scambos TA, Scheuchl B, Schrama EJO, Smith B, Sundal AV, van Angelen JH, van de Berg WJ, van den Broeke MR, Vaughan DG, Velicogna I, Wahr J, Whitehouse PL, Wingham DJ, Yi D, Young D, Zwally HJ. A Reconciled Estimate of Ice-Sheet Mass Balance. Science 2012. [DOI: 10.1126/science.1228102] [Citation(s) in RCA: 1100] [Impact Index Per Article: 91.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Andrew Shepherd
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Erik R. Ivins
- Jet Propulsion Laboratory, M/S 300-233, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
| | - Geruo A
- Department of Physics, University of Colorado, Boulder, CO 80309–0390, USA
| | - Valentina R. Barletta
- Geodynamics Department, Technical University of Denmark, DTU SPACE, National Space Institute, Elektrovej, Building 327, DK-2800 Kgs. Lyngby, Denmark
| | - Mike J. Bentley
- Department of Geography, Durham University, South Road, Durham DH1 3LE, UK
| | - Srinivas Bettadpur
- Center for Space Research, University of Texas at Austin, 3925 West Braker Lane, Suite 200, Austin, TX 78759–5321, USA
| | - Kate H. Briggs
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - David H. Bromwich
- Polar Meteorology Group, Byrd Polar Research Center, and Atmospheric Sciences Program, Department of Geography, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210, USA
| | - René Forsberg
- Geodynamics Department, Technical University of Denmark, DTU SPACE, National Space Institute, Elektrovej, Building 327, DK-2800 Kgs. Lyngby, Denmark
| | - Natalia Galin
- Centre for Polar Observation and Modelling, Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Martin Horwath
- Institut für Astronomische und Physikalische Geodäsie, Technische Universität München, Arcisstraße 21, 80333 München, Germany
| | - Stan Jacobs
- Lamont-Doherty Earth Observatory (LDEO), 205 Oceanography, 61 Route 9W - Post Office Box 1000, Palisades, NY 10964, USA
| | - Ian Joughin
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105–6698, USA
| | - Matt A. King
- School of Civil Engineering and Geosciences, Cassie Building, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
- School of Geography and Environmental Studies, University of Tasmania, Hobart 7001, Australia
| | - Jan T. M. Lenaerts
- Utrecht University, Institute for Marine and Atmospheric Research, Princetonplein 5, Utrecht, Netherlands
| | - Jilu Li
- Center for Remote Sensing of Ice Sheets, University of Kansas, Nichols Hall, 2335 Irving Hill Road, Lawrence, KS 66045, USA
| | - Stefan R. M. Ligtenberg
- Utrecht University, Institute for Marine and Atmospheric Research, Princetonplein 5, Utrecht, Netherlands
| | - Adrian Luckman
- Department of Geography, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Scott B. Luthcke
- National Aeronautical and Space Administration (NASA) Goddard Space Flight Center, Planetary Geodynamics Laboratory, Greenbelt, MD 20771, USA
| | - Malcolm McMillan
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Rakia Meister
- Centre for Polar Observation and Modelling, Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Glenn Milne
- Department of Earth Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Jeremie Mouginot
- Department of Earth System Science, University of California, 3226 Croul Hall, Irvine, CA 92697–3100, USA
| | - Alan Muir
- Centre for Polar Observation and Modelling, Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Julien P. Nicolas
- Polar Meteorology Group, Byrd Polar Research Center, and Atmospheric Sciences Program, Department of Geography, The Ohio State University, 1090 Carmack Road, Columbus, OH 43210, USA
| | - John Paden
- Center for Remote Sensing of Ice Sheets, University of Kansas, Nichols Hall, 2335 Irving Hill Road, Lawrence, KS 66045, USA
| | - Antony J. Payne
- School of Geographical Sciences, University of Bristol, Bristol BS8 1SS, UK
| | - Hamish Pritchard
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Eric Rignot
- Jet Propulsion Laboratory, M/S 300-233, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
- Department of Earth System Science, University of California, 3226 Croul Hall, Irvine, CA 92697–3100, USA
| | - Helmut Rott
- Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria
| | - Louise Sandberg Sørensen
- Geodynamics Department, Technical University of Denmark, DTU SPACE, National Space Institute, Elektrovej, Building 327, DK-2800 Kgs. Lyngby, Denmark
| | - Ted A. Scambos
- National Snow and Ice Data Center, University of Colorado, Boulder, CO 80309, USA
| | - Bernd Scheuchl
- Department of Earth System Science, University of California, 3226 Croul Hall, Irvine, CA 92697–3100, USA
| | - Ernst J. O. Schrama
- Delft University of Technology, Faculty of Aerospace Engineering, Kluyverweg 1, 2629 HS Delft, Netherlands
| | - Ben Smith
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105–6698, USA
| | - Aud V. Sundal
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - Jan H. van Angelen
- Utrecht University, Institute for Marine and Atmospheric Research, Princetonplein 5, Utrecht, Netherlands
| | - Willem J. van de Berg
- Utrecht University, Institute for Marine and Atmospheric Research, Princetonplein 5, Utrecht, Netherlands
| | - Michiel R. van den Broeke
- Utrecht University, Institute for Marine and Atmospheric Research, Princetonplein 5, Utrecht, Netherlands
| | - David G. Vaughan
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
| | - Isabella Velicogna
- Jet Propulsion Laboratory, M/S 300-233, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
- Department of Earth System Science, University of California, 3226 Croul Hall, Irvine, CA 92697–3100, USA
| | - John Wahr
- Department of Physics, University of Colorado, Boulder, CO 80309–0390, USA
| | | | - Duncan J. Wingham
- Centre for Polar Observation and Modelling, Department of Earth Sciences, University College London, London WC1E 6BT, UK
| | - Donghui Yi
- SGT Incorporated, NASA Goddard Space Flight Center, Cryospheric Sciences Laboratory, Code 615 Greenbelt, MD 20771, USA
| | - Duncan Young
- Institute for Geophysics, University of Texas, Austin, TX 78759, USA
| | - H. Jay Zwally
- NASA Goddard Space Flight Center, Cryospheric Sciences Laboratory, Code 615 Greenbelt, MD 20771, USA
| |
Collapse
|
6
|
Abstract
The melting of polar ice sheets is a major contributor to global sea-level rise. Early estimates of the mass lost from the Greenland ice cap, based on satellite gravity data collected by the Gravity Recovery and Climate Experiment, have widely varied. Although the continentally and decadally averaged estimated trends have now more or less converged, to this date, there has been little clarity on the detailed spatial distribution of Greenland's mass loss and how the geographical pattern has varied on relatively shorter time scales. Here, we present a spatially and temporally resolved estimation of the ice mass change over Greenland between April of 2002 and August of 2011. Although the total mass loss trend has remained linear, actively changing areas of mass loss were concentrated on the southeastern and northwestern coasts, with ice mass in the center of Greenland steadily increasing over the decade.
Collapse
|
7
|
Goldberg DN, Little CM, Sergienko OV, Gnanadesikan A, Hallberg R, Oppenheimer M. Investigation of land ice-ocean interaction with a fully coupled ice-ocean model: 1. Model description and behavior. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jf002246] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
8
|
Kwok R, Cunningham GF, Manizade SS, Krabill WB. Arctic sea ice freeboard from IceBridge acquisitions in 2009: Estimates and comparisons with ICESat. ACTA ACUST UNITED AC 2012. [DOI: 10.1029/2011jc007654] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
9
|
Rinne EJ, Shepherd A, Palmer S, van den Broeke MR, Muir A, Ettema J, Wingham D. On the recent elevation changes at the Flade Isblink Ice Cap, northern Greenland. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jf001972] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
10
|
Seale A, Christoffersen P, Mugford RI, O'Leary M. Ocean forcing of the Greenland Ice Sheet: Calving fronts and patterns of retreat identified by automatic satellite monitoring of eastern outlet glaciers. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jf001847] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
11
|
Chen JL, Wilson CR, Tapley BD. Interannual variability of Greenland ice losses from satellite gravimetry. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010jb007789] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
12
|
Committed sea-level rise for the next century from Greenland ice sheet dynamics during the past decade. Proc Natl Acad Sci U S A 2011; 108:8978-83. [PMID: 21576500 DOI: 10.1073/pnas.1017313108] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We use a three-dimensional, higher-order ice flow model and a realistic initial condition to simulate dynamic perturbations to the Greenland ice sheet during the last decade and to assess their contribution to sea level by 2100. Starting from our initial condition, we apply a time series of observationally constrained dynamic perturbations at the marine termini of Greenland's three largest outlet glaciers, Jakobshavn Isbræ, Helheim Glacier, and Kangerdlugssuaq Glacier. The initial and long-term diffusive thinning within each glacier catchment is then integrated spatially and temporally to calculate a minimum sea-level contribution of approximately 1 ± 0.4 mm from these three glaciers by 2100. Based on scaling arguments, we extend our modeling to all of Greenland and estimate a minimum dynamic sea-level contribution of approximately 6 ± 2 mm by 2100. This estimate of committed sea-level rise is a minimum because it ignores mass loss due to future changes in ice sheet dynamics or surface mass balance. Importantly, > 75% of this value is from the long-term, diffusive response of the ice sheet, suggesting that the majority of sea-level rise from Greenland dynamics during the past decade is yet to come. Assuming similar and recurring forcing in future decades and a self-similar ice dynamical response, we estimate an upper bound of 45 mm of sea-level rise from Greenland dynamics by 2100. These estimates are constrained by recent observations of dynamic mass loss in Greenland and by realistic model behavior that accounts for both the long-term cumulative mass loss and its decay following episodic boundary forcing.
Collapse
|
13
|
Observed Mass Balance of Mountain Glaciers and Greenland Ice Sheet in the 20th Century and the Present Trends. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/978-94-007-2063-3_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023]
|
14
|
Cox KA, Stanford JD, McVicar AJ, Rohling EJ, Heywood KJ, Bacon S, Bolshaw M, Dodd PA, De la Rosa S, Wilkinson D. Interannual variability of Arctic sea ice export into the East Greenland Current. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jc006227] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
15
|
Khan SA, Liu L, Wahr J, Howat I, Joughin I, van Dam T, Fleming K. GPS measurements of crustal uplift near Jakobshavn Isbræ due to glacial ice mass loss. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2010jb007490] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
16
|
|
17
|
van den Broeke M, Bamber J, Ettema J, Rignot E, Schrama E, van de Berg WJ, van Meijgaard E, Velicogna I, Wouters B. Partitioning recent Greenland mass loss. Science 2010; 326:984-6. [PMID: 19965509 DOI: 10.1126/science.1178176] [Citation(s) in RCA: 693] [Impact Index Per Article: 49.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mass budget calculations, validated with satellite gravity observations [from the Gravity Recovery and Climate Experiment (GRACE) satellites], enable us to quantify the individual components of recent Greenland mass loss. The total 2000-2008 mass loss of approximately 1500 gigatons, equivalent to 0.46 millimeters per year of global sea level rise, is equally split between surface processes (runoff and precipitation) and ice dynamics. Without the moderating effects of increased snowfall and refreezing, post-1996 Greenland ice sheet mass losses would have been 100% higher. Since 2006, high summer melt rates have increased Greenland ice sheet mass loss to 273 gigatons per year (0.75 millimeters per year of equivalent sea level rise). The seasonal cycle in surface mass balance fully accounts for detrended GRACE mass variations, confirming insignificant subannual variation in ice sheet discharge.
Collapse
|
18
|
Goldberg D, Holland DM, Schoof C. Grounding line movement and ice shelf buttressing in marine ice sheets. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2008jf001227] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
19
|
Joughin I, Howat IM, Fahnestock M, Smith B, Krabill W, Alley RB, Stern H, Truffer M. Continued evolution of Jakobshavn Isbrae following its rapid speedup. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008jf001023] [Citation(s) in RCA: 182] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
20
|
Reeh N. A nonsteady-state firn-densification model for the percolation zone of a glacier. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jf000746] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
21
|
Empirical Retrieval of Surface Melt Magnitude from Coupled MODIS Optical and Thermal Measurements over the Greenland Ice Sheet during the 2001 Ablation Season. SENSORS 2008; 8:4915-4947. [PMID: 27873793 PMCID: PMC3705479 DOI: 10.3390/s8084915] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 07/22/2008] [Accepted: 08/25/2008] [Indexed: 11/17/2022]
Abstract
Accelerated ice flow near the equilibrium line of west-central Greenland Ice Sheet (GIS) has been attributed to an increase in infiltrated surface melt water as a response to climate warming. The assessment of surface melting events must be more than the detection of melt onset or extent. Retrieval of surface melt magnitude is necessary to improve understanding of ice sheet flow and surface melt coupling. In this paper, we report on a new technique to quantify the magnitude of surface melt. Cloud-free dates of June 10, July 5, 7, 9, and 11, 2001 Moderate Resolution Imaging Spectroradiometer (MODIS) daily reflectance Band 5 (1.230-1.250μm) and surface temperature images rescaled to 1km over western Greenland were used in the retrieval algorithm. An optical-thermal feature space partitioned as a function of melt magnitude was derived using a one-dimensional thermal snowmelt model (SNTHERM89). SNTHERM89 was forced by hourly meteorological data from the Greenland Climate Network (GC-Net) at reference sites spanning dry snow, percolation, and wet snow zones in the Jakobshavn drainage basin in western GIS. Melt magnitude or effective melt (E-melt) was derived for satellite composite periods covering May, June, and July displaying low fractions (0-1%) at elevations greater than 2500m and fractions at or greater than 15% at elevations lower than 1000m assessed for only the upper 5 cm of the snow surface. Validation of E-melt involved comparison of intensity to dry and wet zones determined from QSCAT backscatter. Higher intensities (> 8%) were distributed in wet snow zones, while lower intensities were grouped in dry zones at a first order accuracy of ∼ ±2%.
Collapse
|
22
|
Moon T, Joughin I. Changes in ice front position on Greenland's outlet glaciers from 1992 to 2007. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2007jf000927] [Citation(s) in RCA: 217] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
23
|
Abstract
The term "tipping point" commonly refers to a critical threshold at which a tiny perturbation can qualitatively alter the state or development of a system. Here we introduce the term "tipping element" to describe large-scale components of the Earth system that may pass a tipping point. We critically evaluate potential policy-relevant tipping elements in the climate system under anthropogenic forcing, drawing on the pertinent literature and a recent international workshop to compile a short list, and we assess where their tipping points lie. An expert elicitation is used to help rank their sensitivity to global warming and the uncertainty about the underlying physical mechanisms. Then we explain how, in principle, early warning systems could be established to detect the proximity of some tipping points.
Collapse
|
24
|
Pritchard HD, Vaughan DG. Widespread acceleration of tidewater glaciers on the Antarctic Peninsula. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jf000597] [Citation(s) in RCA: 172] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
25
|
Shepherd A, Wingham D. Recent Sea-Level Contributions of the Antarctic and Greenland Ice Sheets. Science 2007; 315:1529-32. [PMID: 17363663 DOI: 10.1126/science.1136776] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
After a century of polar exploration, the past decade of satellite measurements has painted an altogether new picture of how Earth's ice sheets are changing. As global temperatures have risen, so have rates of snowfall, ice melting, and glacier flow. Although the balance between these opposing processes has varied considerably on a regional scale, data show that Antarctica and Greenland are each losing mass overall. Our best estimate of their combined imbalance is about 125 gigatons per year of ice, enough to raise sea level by 0.35 millimeters per year. This is only a modest contribution to the present rate of sea-level rise of 3.0 millimeters per year. However, much of the loss from Antarctica and Greenland is the result of the flow of ice to the ocean from ice streams and glaciers, which has accelerated over the past decade. In both continents, there are suspected triggers for the accelerated ice discharge-surface and ocean warming, respectively-and, over the course of the 21st century, these processes could rapidly counteract the snowfall gains predicted by present coupled climate models.
Collapse
Affiliation(s)
- Andrew Shepherd
- Centre for Polar Observation and Modelling, School of Geosciences, University of Edinburgh, EH8 9XP, UK.
| | | |
Collapse
|
26
|
Luthcke SB, Zwally HJ, Abdalati W, Rowlands DD, Ray RD, Nerem RS, Lemoine FG, McCarthy JJ, Chinn DS. Recent Greenland Ice Mass Loss by Drainage System from Satellite Gravity Observations. Science 2006; 314:1286-9. [PMID: 17053112 DOI: 10.1126/science.1130776] [Citation(s) in RCA: 308] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Mass changes of the Greenland Ice Sheet resolved by drainage system regions were derived from a local mass concentration analysis of NASA-Deutsches Zentrum für Luftund Raumfahrt Gravity Recovery and Climate Experiment (GRACE mission) observations. From 2003 to 2005, the ice sheet lost 101 +/- 16 gigaton/year, with a gain of 54 gigaton/year above 2000 meters and a loss of 155 gigaton/year at lower elevations. The lower elevations show a large seasonal cycle, with mass losses during summer melting followed by gains from fall through spring. The overall rate of loss reflects a considerable change in trend (-113 +/- 17 gigaton/year) from a near balance during the 1990s but is smaller than some other recent estimates.
Collapse
Affiliation(s)
- S B Luthcke
- Planetary Geodynamics Laboratory, Code 698, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Velicogna I, Wahr J. Acceleration of Greenland ice mass loss in spring 2004. Nature 2006; 443:329-31. [PMID: 16988710 DOI: 10.1038/nature05168] [Citation(s) in RCA: 291] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2006] [Accepted: 08/14/2006] [Indexed: 11/09/2022]
Abstract
In 2001 the Intergovernmental Panel on Climate Change projected the contribution to sea level rise from the Greenland ice sheet to be between -0.02 and +0.09 m from 1990 to 2100 (ref. 1). However, recent work has suggested that the ice sheet responds more quickly to climate perturbations than previously thought, particularly near the coast. Here we use a satellite gravity survey by the Gravity Recovery and Climate Experiment (GRACE) conducted from April 2002 to April 2006 to provide an independent estimate of the contribution of Greenland ice mass loss to sea level change. We detect an ice mass loss of 248 +/- 36 km3 yr(-1), equivalent to a global sea level rise of 0.5 +/- 0.1 mm yr(-1). The rate of ice loss increased by 250 per cent between the periods April 2002 to April 2004 and May 2004 to April 2006, almost entirely due to accelerated rates of ice loss in southern Greenland; the rate of mass loss in north Greenland was almost constant. Continued monitoring will be needed to identify any future changes in the rate of ice loss in Greenland.
Collapse
Affiliation(s)
- Isabella Velicogna
- Department of Physics and CIRES, University of Colorado, Boulder, Colorado 80309-0390, USA.
| | | |
Collapse
|
28
|
Arthern RJ, Hindmarsh RCA. Determining the contribution of Antarctica to sea-level rise using data assimilation methods. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2006; 364:1841-65. [PMID: 16782612 DOI: 10.1098/rsta.2006.1801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The problem of forecasting the future behaviour of the Antarctic ice sheet is considered. We describe a method for optimizing this forecast by combining a model of ice sheet flow with observations. Under certain assumptions, a linearized model of glacial flow can be combined with observations of the thickness change, snow accumulation, and ice-flow, to forecast the Antarctic contribution to sea-level rise. Numerical simulations show that this approach can potentially be used to test whether changes observed in Antarctica are consistent with the natural forcing of a stable ice sheet by snowfall fluctuations. To make predictions under less restrictive assumptions, improvements in models of ice flow are needed. Some of the challenges that this prediction problem poses are highlighted, and potentially useful approaches drawn from numerical weather prediction are discussed.
Collapse
Affiliation(s)
- Robert J Arthern
- British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
| | | |
Collapse
|
29
|
Otto-Bliesner BL, Marshall SJ, Overpeck JT, Miller GH, Hu A. Simulating Arctic Climate Warmth and Icefield Retreat in the Last Interglaciation. Science 2006; 311:1751-3. [PMID: 16556838 DOI: 10.1126/science.1120808] [Citation(s) in RCA: 314] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In the future, Arctic warming and the melting of polar glaciers will be considerable, but the magnitude of both is uncertain. We used a global climate model, a dynamic ice sheet model, and paleoclimatic data to evaluate Northern Hemisphere high-latitude warming and its impact on Arctic icefields during the Last Interglaciation. Our simulated climate matches paleoclimatic observations of past warming, and the combination of physically based climate and ice-sheet modeling with ice-core constraints indicate that the Greenland Ice Sheet and other circum-Arctic ice fields likely contributed 2.2 to 3.4 meters of sea-level rise during the Last Interglaciation.
Collapse
Affiliation(s)
- Bette L Otto-Bliesner
- Climate and Global Dynamics Division, National Center for Atmospheric Research (NCAR), Boulder, CO 80305, USA.
| | | | | | | | | |
Collapse
|
30
|
Abstract
Using satellite radar interferometry observations of Greenland, we detected widespread glacier acceleration below 66 degrees north between 1996 and 2000, which rapidly expanded to 70 degrees north in 2005. Accelerated ice discharge in the west and particularly in the east doubled the ice sheet mass deficit in the last decade from 90 to 220 cubic kilometers per year. As more glaciers accelerate farther north, the contribution of Greenland to sea-level rise will continue to increase.
Collapse
Affiliation(s)
- Eric Rignot
- Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 300-319, Pasadena, CA 91109-8099, USA.
| | | |
Collapse
|
31
|
|
32
|
Johannessen OM, Khvorostovsky K, Miles MW, Bobylev LP. Recent ice-sheet growth in the interior of Greenland. Science 2005; 310:1013-6. [PMID: 16239440 DOI: 10.1126/science.1115356] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A continuous data set of Greenland Ice Sheet altimeter height from European Remote Sensing satellites (ERS-1 and ERS-2), 1992 to 2003, has been analyzed. An increase of 6.4 +/- 0.2 centimeters per year (cm/year) is found in the vast interior areas above 1500 meters, in contrast to previous reports of high-elevation balance. Below 1500 meters, the elevation-change rate is -2.0 +/- 0.9 cm/year, in qualitative agreement with reported thinning in the ice-sheet margins. Averaged over the study area, the increase is 5.4 +/- 0.2 cm/year, or approximately 60 cm over 11 years, or approximately 54 cm when corrected for isostatic uplift. Winter elevation changes are shown to be linked to the North Atlantic Oscillation.
Collapse
Affiliation(s)
- Ola M Johannessen
- Mohn-Sverdrup Center for Global Ocean Studies and Operational Oceanography, Nansen Environmental and Remote Sensing Center, Bergen, 5006, Norway.
| | | | | | | |
Collapse
|
33
|
Davis CH, Li Y, McConnell JR, Frey MM, Hanna E. Snowfall-Driven Growth in East Antarctic Ice Sheet Mitigates Recent Sea-Level Rise. Science 2005; 308:1898-901. [PMID: 15905362 DOI: 10.1126/science.1110662] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Satellite radar altimetry measurements indicate that the East Antarctic ice-sheet interior north of 81.6 degrees S increased in mass by 45 +/- 7 billion metric tons per year from 1992 to 2003. Comparisons with contemporaneous meteorological model snowfall estimates suggest that the gain in mass was associated with increased precipitation. A gain of this magnitude is enough to slow sea-level rise by 0.12 +/- 0.02 millimeters per year.
Collapse
Affiliation(s)
- Curt H Davis
- Department of Electrical and Computer Engineering, University of Missouri-Columbia, Columbia, MO 65211, USA.
| | | | | | | | | |
Collapse
|
34
|
Macdonald RW, Harner T, Fyfe J. Recent climate change in the Arctic and its impact on contaminant pathways and interpretation of temporal trend data. THE SCIENCE OF THE TOTAL ENVIRONMENT 2005; 342:5-86. [PMID: 15866268 DOI: 10.1016/j.scitotenv.2004.12.059] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The Arctic has undergone dramatic change during the past decade. The observed changes include atmospheric sea-level pressure, wind fields, sea-ice drift, ice cover, length of melt season, change in precipitation patterns, change in hydrology and change in ocean currents and watermass distribution. It is likely that these primary changes have altered the carbon cycle and biological systems, but the difficulty of observing these together with sporadic, incomplete time series makes it difficult to evaluate what the changes have been. Because contaminants enter global systems and transport through air and water, the changes listed above will clearly alter contaminant pathways. Here, we review what is known about recent changes using the Arctic Oscillation as a proxy to help us understand the forms under which global change will be manifest in the Arctic. For Pb, Cd and Zn, the Arctic is likely to become a more effective trap because precipitation is likely to increase. In the case of Cd, the natural cycle in the ocean appears to have a much greater potential to alter exposure than do human releases of this metal. Mercury has an especially complex cycle in the Arctic including a unique scavenging process (mercury depletion events), biomagnifying foodwebs, and chemical transformations such as methylation. The observation that mercury seems to be increasing in a number of aquatic species whereas atmospheric gaseous mercury shows little sign of change suggests that factors related to change in the physical system (ice cover, permafrost degradation, organic carbon cycling) may be more important than human activities. Organochlorine contaminants offer a surprising array of possibilities for changed pathways. To change in precipitation patterns can be added change in ice cover (air-water exchange), change in food webs either from the top down or from the bottom up (biomagnification), change in the organic carbon cycle and change in diets. Perhaps the most interesting possibility, presently difficult to predict, is combination of immune suppression together with expanding ranges of disease vectors. Finally, biotransport through migratory species is exceptionally vulnerable to changes in migration strength or in migration pathway-in the Arctic, change in the distribution of ice and temperature may already have caused such changes. Hydrocarbons, which tend to impact surfaces, will be mostly affected by change in the ice climate (distribution and drift tracks). Perhaps the most dramatic changes will occur because our view of the Arctic Ocean will change as it becomes more amenable to transport, tourism and mineral exploration on the shelves. Radionuclides have tended not to produce a radiological problem in the Arctic; nevertheless one pathway, the ice, remains a risk because it can accrue, concentrate and transport radio-contaminated sediments. This pathway is sensitive to where ice is produced, what the transport pathways of ice are, and where ice is finally melted-all strong candidates for change during the coming century. The changes that have already occurred in the Arctic and those that are projected to occur have an effect on contaminant time series including direct measurements (air, water, biota) or proxies (sediment cores, ice cores, archive material). Although these 'system' changes can alter the flux and concentrations at given sites in a number of obvious ways, they have been all but ignored in the interpretation of such time series. To understand properly what trends mean, especially in complex 'recorders' such as seals, walrus and polar bears, demands a more thorough approach to time series by collecting data in a number of media coherently. Presently, a major reservoir for contaminants and the one most directly connected to biological uptake in species at greatest risk-the ocean-practically lacks such time series.
Collapse
Affiliation(s)
- R W Macdonald
- Institute of Ocean Sciences, Department of Fisheries and Oceans, P.O. Box 6000, Sydney, BC, Canada V8L 4B2.
| | | | | |
Collapse
|
35
|
Joughin I, Abdalati W, Fahnestock M. Large fluctuations in speed on Greenland's Jakobshavn Isbrae glacier. Nature 2005; 432:608-10. [PMID: 15577906 DOI: 10.1038/nature03130] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 10/08/2004] [Indexed: 11/09/2022]
Abstract
It is important to understand recent changes in the velocity of Greenland glaciers because the mass balance of the Greenland Ice Sheet is partly determined by the flow rates of these outlets. Jakobshavn Isbrae is Greenland's largest outlet glacier, draining about 6.5 per cent of the ice-sheet area, and it has been surveyed repeatedly since 1991 (ref. 2). Here we use remote sensing data to measure the velocity of Jakobshavn Isbrae between 1992 and 2003. We detect large variability of the velocity over time, including a slowing down from 6,700 m yr(-1) in 1985 to 5,700 m yr(-1) in 1992, and a subsequent speeding up to 9,400 m yr(-1) by 2000 and 12,600 m yr(-1) in 2003. These changes are consistent with earlier evidence for thickening of the glacier in the early 1990s and rapid thinning thereafter. Our observations indicate that fast-flowing glaciers can significantly alter ice discharge at sub-decadal timescales, with at least a potential to respond rapidly to a changing climate.
Collapse
Affiliation(s)
- Ian Joughin
- Jet Propulsion Lab, California Institute of Technology, USA.
| | | | | |
Collapse
|
36
|
|
37
|
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] [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.
Collapse
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.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
|
39
|
|
40
|
Ohmura A. Cryosphere during the twentieth century. GEOPHYSICAL MONOGRAPH SERIES 2004. [DOI: 10.1029/150gm19] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
41
|
Box JE. Greenland ice sheet surface mass balance 1991–2000: Application of Polar MM5 mesoscale model and in situ data. ACTA ACUST UNITED AC 2004. [DOI: 10.1029/2003jd004451] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
42
|
Mote TL. Estimation of runoff rates, mass balance, and elevation changes on the Greenland ice sheet from passive microwave observations. ACTA ACUST UNITED AC 2003. [DOI: 10.1029/2001jd002032] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
43
|
Abstract
Recent advances in the determination of the mass balance of polar ice sheets show that the Greenland Ice Sheet is losing mass by near-coastal thinning, and that the West Antarctic Ice Sheet, with thickening in the west and thinning in the north, is probably thinning overall. The mass imbalance of the East Antarctic Ice Sheet is likely to be small, but even its sign cannot yet be determined. Large sectors of ice in southeast Greenland, the Amundsen Sea Embayment of West Antarctica, and the Antarctic Peninsula are changing quite rapidly as a result of processes not yet understood.
Collapse
Affiliation(s)
- Eric Rignot
- Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 300-235, Pasadena, CA 91109, USA.
| | | |
Collapse
|
44
|
Cox CM, Chao BF. Detection of a large-scale mass redistribution in the terrestrial system since 1998. Science 2002; 297:831-3. [PMID: 12161652 DOI: 10.1126/science.1072188] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Earth's dynamic oblateness (J2) had been undergoing a decrease, according to space geodetic observations over the past 25 years, until around 1998, when it switched quite suddenly to an increasing trend that has continued to the present. The secular decrease in J2 resulted primarily from the postglacial rebound in the mantle. The present increase, whose geophysical cause(s) are uncertain, thus signifies a large change in global mass distribution with a J2 effect that considerably overshadows that of mantle rebound.
Collapse
Affiliation(s)
- Christopher M Cox
- Raytheon Information Technology and Scientific Services (ITSS), Space Geodesy Branch, NASA Goddard Space Flight Center, Code 926, Greenbelt, MD 20771, USA
| | | |
Collapse
|
45
|
Arendt AA, Echelmeyer KA, Harrison WD, Lingle CS, Valentine VB. Rapid wastage of Alaska glaciers and their contribution to rising sea level. Science 2002; 297:382-6. [PMID: 12130781 DOI: 10.1126/science.1072497] [Citation(s) in RCA: 522] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We have used airborne laser altimetry to estimate volume changes of 67 glaciers in Alaska from the mid-1950s to the mid-1990s. The average rate of thickness change of these glaciers was -0.52 m/year. Extrapolation to all glaciers in Alaska yields an estimated total annual volume change of -52 +/- 15 km3/year (water equivalent), equivalent to a rise in sea level (SLE) of 0.14 +/- 0.04 mm/year. Repeat measurements of 28 glaciers from the mid-1990s to 2000-2001 suggest an increased average rate of thinning, -1.8 m/year. This leads to an extrapolated annual volume loss from Alaska glaciers equal to -96 +/- 35 km3/year, or 0.27 +/- 0.10 mm/year SLE, during the past decade. These recent losses are nearly double the estimated annual loss from the entire Greenland Ice Sheet during the same time period and are much higher than previously published loss estimates for Alaska glaciers. They form the largest glaciological contribution to rising sea level yet measured.
Collapse
Affiliation(s)
- Anthony A Arendt
- Geophysical Institute, University of Alaska, 903 Koyukuk Drive, Post Office Box 757320, Fairbanks, AK 99775, USA.
| | | | | | | | | |
Collapse
|
46
|
Affiliation(s)
- Mark F Meier
- INSTAAR and Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA.
| | | |
Collapse
|
47
|
Welker JM, Fahnestock JT, Henry GHR, O'Dea KW, Piper RE. Microbial activity discovered in previously ice-entombed Arctic ecosystems. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2002eo000198] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
48
|
|
49
|
Fahnestock M, Abdalati W, Joughin I, Brozena J, Gogineni P. High geothermal heat flow, Basal melt, and the origin of rapid ice flow in central Greenland. Science 2001; 294:2338-42. [PMID: 11743197 DOI: 10.1126/science.1065370] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Age-depth relations from internal layering reveal a large region of rapid basal melting in Greenland. Melt is localized at the onset of rapid ice flow in the large ice stream that drains north off the summit dome and other areas in the northeast quadrant of the ice sheet. Locally, high melt rates indicate geothermal fluxes 15 to 30 times continental background. The southern limit of melt coincides with magnetic anomalies and topography that suggest a volcanic origin.
Collapse
Affiliation(s)
- M Fahnestock
- Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742, USA
| | | | | | | | | |
Collapse
|
50
|
Davis CH, McConnell JR, Bolzan J, Bamber JL, Thomas RH, Mosley-Thompson E. Elevation change of the southern Greenland ice sheet from 1978 to 1988: Interpretation. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900167] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|