Bedrock displacements in Greenland manifest ice mass variations, climate cycles and climate change

The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. The entire network is uplifting in response to past and present-day changes in ice mass. Crustal displacement is largely accounted for by an annual oscillation superimposed on a sustained trend. The oscillation is driven by earth’s elastic response to seasonal variations in ice mass and air mass (i.e., atmospheric pressure). Observed vertical velocities are higher and often much higher than predicted rates of postglacial rebound (PGR), implying that uplift is usually dominated by the solid earth’s instantaneous elastic response to contemporary losses in ice mass rather than PGR. Superimposed on longer-term trends, an anomalous ‘pulse’ of uplift accumulated at many GNET stations during an approximate six-month period in 2010. This anomalous uplift is spatially correlated with the 2010 melting day anomaly.

[1]  G. Milne,et al.  The influence of decadal‐ to millennial‐scale ice mass changes on present‐day vertical land motion in Greenland: Implications for the interpretation of GPS observations , 2011 .

[2]  M. Watkins,et al.  GRACE Measurements of Mass Variability in the Earth System , 2004, Science.

[3]  W. Wal,et al.  Using postglacial sea level, crustal velocities and gravity-rate-of-change to constrain the influence of thermal effects on mantle lateral heterogeneities , 2008 .

[4]  T. Dixon,et al.  Accelerating uplift in the North Atlantic region as an indicator of ice loss , 2010 .

[5]  M. R. van den Broeke,et al.  Partitioning Recent Greenland Mass Loss , 2009, Science.

[6]  J. Wahr,et al.  Elastic uplift in southeast Greenland due to rapid ice mass loss , 2007 .

[7]  E. L. Meur,et al.  A model computation of the temporal changes of surface gravity and geoidal signal induced by the evolving Greenland ice sheet , 2001 .

[8]  Eric Rignot,et al.  Mass Balance of Polar Ice Sheets , 2002, Science.

[9]  M. Bevis,et al.  Geodetic measurement of the local elastic response to the changing mass of water in Lago Laja, Chile , 2004 .

[10]  Michael Bevis,et al.  Geodetic measurements of vertical crustal velocity in West Antarctica and the implications for ice mass balance , 2009 .

[11]  W. Peltier.  GLOBAL GLACIAL ISOSTASY AND THE SURFACE OF THE ICE-AGE EARTH: The ICE-5G (VM2) Model and GRACE , 2004 .

[12]  D. L. Anderson,et al.  Preliminary reference earth model , 1981 .

[13]  Sheng-Hung Wang,et al.  Greenland Ice Sheet Surface Mass Balance Variability (1988–2004) from Calibrated Polar MM5 Output* , 2006 .

[14]  M. Bevis,et al.  Spread of ice mass loss into northwest Greenland observed by GRACE and GPS , 2010 .

[15]  Archie Paulson,et al.  FAST TRACK PAPER: Inference of mantle viscosity from GRACE and relative sea level data , 2007 .

[16]  D. Alsdorf,et al.  Seasonal fluctuations in the mass of the Amazon River system and Earth's elastic response , 2005 .

[17]  Ian M. Howat,et al.  Mass balance of Greenland's three largest outlet glaciers, 2000–2010 , 2011 .

[18]  Xavier Fettweis,et al.  The role of albedo and accumulation in the 2010 melting record in Greenland , 2011 .

[19]  J. Wahr,et al.  Measurements of Time-Variable Gravity Show Mass Loss in Antarctica , 2006, Science.

[20]  M. R. van den Broeke,et al.  Elevation Changes in Antarctica Mainly Determined by Accumulation Variability , 2008, Science.

[21]  Y. Bock,et al.  Anatomy of apparent seasonal variations from GPS‐derived site position time series , 2001 .