Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018

Significance We reconstruct the mass balance of the Greenland Ice Sheet for the past 46 years by comparing glacier ice discharge into the ocean with interior accumulation of snowfall from regional atmospheric climate models over 260 drainage basins. The mass balance started to deviate from its natural range of variability in the 1980s. The mass loss has increased sixfold since the 1980s. Greenland has raised sea level by 13.7 mm since 1972, half during the last 8 years. We reconstruct the mass balance of the Greenland Ice Sheet using a comprehensive survey of thickness, surface elevation, velocity, and surface mass balance (SMB) of 260 glaciers from 1972 to 2018. We calculate mass discharge, D, into the ocean directly for 107 glaciers (85% of D) and indirectly for 110 glaciers (15%) using velocity-scaled reference fluxes. The decadal mass balance switched from a mass gain of +47 ± 21 Gt/y in 1972–1980 to a loss of 51 ± 17 Gt/y in 1980–1990. The mass loss increased from 41 ± 17 Gt/y in 1990–2000, to 187 ± 17 Gt/y in 2000–2010, to 286 ± 20 Gt/y in 2010–2018, or sixfold since the 1980s, or 80 ± 6 Gt/y per decade, on average. The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers, which illustrates the difficulty of extrapolating short records into longer-term trends. Cumulated since 1972, the largest contributions to global sea level rise are from northwest (4.4 ± 0.2 mm), southeast (3.0 ± 0.3 mm), and central west (2.0 ± 0.2 mm) Greenland, with a total 13.7 ± 1.1 mm for the ice sheet. The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.

[1]  The Imbie Team.  Mass balance of the Greenland Ice Sheet from 1992 to 2018 , 2020 .

[2]  A. Weidick.  Historical t1uctuations of calving glaciers in South and West Greenland , 2020 .

[3]  A. Weidick.  Present-day expansion af the southern part of the Inland lee , 2020 .

[4]  M. R. van den Broeke,et al.  Seasonal to decadal variability in ice discharge from the Greenland Ice Sheet. , 2018, The cryosphere.

[5]  B. Scheuchl,et al.  Insights on the Surge Behavior of Storstrømmen and L. Bistrup Bræ, Northeast Greenland, Over the Last Century , 2018, Geophysical Research Letters.

[6]  E. Rignot,et al.  A Century of Stability of Avannarleq and Kujalleq Glaciers, West Greenland, Explained Using High‐Resolution Airborne Gravity and Other Data , 2018, Geophysical research letters.

[7]  M. Morlighem,et al.  Vulnerability of Southeast Greenland Glaciers to Warm Atlantic Water From Operation IceBridge and Ocean Melting Greenland Data , 2018, Geophysical research letters.

[8]  L Mayer,et al.  BedMachine v3: Complete Bed Topography and Ocean Bathymetry Mapping of Greenland From Multibeam Echo Sounding Combined With Mass Conservation , 2017, Geophysical research letters.

[9]  S. Lhermitte,et al.  Modelling the climate and surface mass balance of polar ice sheets using RACMO2 – Part 1: Greenland (1958–2016) , 2017 .

[10]  J. Paden,et al.  Bed elevation of Jakobshavn Isbræ, West Greenland, from high‐resolution airborne gravity and other data , 2017 .

[11]  Bernd Scheuchl,et al.  Comprehensive Annual Ice Sheet Velocity Mapping Using Landsat-8, Sentinel-1, and RADARSAT-2 Data , 2017, Remote. Sens..

[12]  M. R. van den Broeke,et al.  A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps , 2017, Nature Communications.

[13]  J. Willis,et al.  Improving Bed Topography Mapping of Greenland Glaciers Using NASA’s Oceans Melting Greenland (OMG) Data , 2016 .

[14]  X. Fettweis,et al.  A daily, 1 km resolution data set of downscaled Greenland ice sheet surface mass balance (1958–2015) , 2016 .

[15]  Willem Jan van de Berg,et al.  A high‐resolution record of Greenland mass balance , 2016 .

[16]  K. Kjær,et al.  Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978–1987 , 2016, Scientific Data.

[17]  E. Willerslev,et al.  Spatial and temporal distribution of mass loss from the Greenland Ice Sheet since AD 1900 , 2015, Nature.

[18]  B. Scheuchl,et al.  Fast retreat of Zachariæ Isstrøm, northeast Greenland , 2015, Science.

[19]  Andy Aschwanden,et al.  Greenland ice sheet mass balance: a review , 2015, Reports on progress in physics. Physical Society.

[20]  Kyle Duncan,et al.  Laser altimetry reveals complex pattern of Greenland Ice Sheet dynamics , 2014, Proceedings of the National Academy of Sciences.

[21]  Isabella Velicogna,et al.  Regional acceleration in ice mass loss from Greenland and Antarctica using GRACE time‐variable gravity data , 2014 .

[22]  B. Smith,et al.  The Greenland Ice Mapping Project (GIMP) land classification and surface elevation data sets , 2014 .

[23]  M. Bevis,et al.  Sustained mass loss of the northeast Greenland ice sheet triggered by regional warming , 2014 .

[24]  Richard R. Forster,et al.  Extensive liquid meltwater storage in firn within the Greenland ice sheet , 2014 .

[25]  Myoung-Jong Noh,et al.  An improved mass budget for the Greenland ice sheet , 2013 .

[26]  Eric Rignot,et al.  A Reconciled Estimate of Ice-Sheet Mass Balance , 2012, Science.

[27]  Ian M. Howat,et al.  A new bed elevation dataset for Greenland , 2012 .

[28]  K. Kjær,et al.  An aerial view of 80 years of climate-related glacier fluctuations in southeast Greenland , 2012 .

[29]  Eric Rignot,et al.  Ice flow in Greenland for the International Polar Year 2008–2009 , 2012 .

[30]  Alun Hubbard,et al.  The response of Petermann Glacier, Greenland, to large calving events, and its future stability in the context of atmospheric and oceanic warming , 2012 .

[31]  J. Gregory,et al.  Revisiting the Earth's sea‐level and energy budgets from 1961 to 2008 , 2011, Geophysical Research Letters.

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

[33]  Eric Rignot,et al.  Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise , 2011 .

[34]  Jack L. Saba,et al.  Greenland ice sheet mass balance: distribution of increased mass loss with climate warming; 2003–07 versus 1992–2002 , 2011, Journal of Glaciology.

[35]  Jemma L. Wadham,et al.  Supraglacial forcing of subglacial drainage in the ablation zone of the Greenland ice sheet , 2010 .

[36]  Eric Rignot,et al.  Mass balance of the Greenland ice sheet from 1958 to 2007 , 2008 .

[37]  H. Gallée,et al.  Estimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries , 2008 .

[38]  Marc Wathelet,et al.  An improved neighborhood algorithm: Parameter conditions and dynamic scaling , 2008 .

[39]  K. Steffen,et al.  Channelized bottom melting and stability of floating ice shelves , 2008 .

[40]  Edward Hanna,et al.  Greenland Ice Sheet mass balance , 2007 .

[41]  T. Scambos,et al.  Rapid Changes in Ice Discharge from Greenland Outlet Glaciers , 2007, Science.

[42]  W. Krabill,et al.  Progressive increase in ice loss from Greenland , 2006 .

[43]  E. Rignot,et al.  Changes in the Velocity Structure of the Greenland Ice Sheet , 2006, Science.

[44]  Jack L. Saba,et al.  Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992-2002 , 2005 .

[45]  Ian Joughin,et al.  Large fluctuations in speed on Greenland's Jakobshavn Isbræ glacier , 2004, Nature.

[46]  Robert N. Swift,et al.  Greenland Ice Sheet: Increased coastal thinning , 2004 .

[47]  J. Legarsky,et al.  Coherent radar ice thickness measurements over the Greenland ice sheet , 2001 .

[48]  Haines,et al.  Elevation change of the southern greenland ice sheet , 1999, Science.

[49]  H. Oerter,et al.  Surge of Storstrømmen, a large oulet glacier from the Inland Ice of North-East Greenland , 1994 .

[50]  H. Zwally,et al.  Growth of Greenland Ice Sheet: Interpretation , 1989, Science.

[51]  A. Weidick.  Studies of Glacier Behaviour and Glacier Mass Balance in Greenland—A Review , 1984 .