Greenland and Antarctica Ice Sheet Mass Changes and Effects on Global Sea Level
Thirteen years of GRACE data provide an excellent picture of the current mass changes of Greenland and Antarctica, with mass loss in the GRACE period 2002–2015 amounting to 265 ± 25 GT/year for Greenland (including peripheral ice caps), and 95 ± 50 GT/year for Antarctica, corresponding to 0.72 and 0.26 mm/year average global sea level change. A significant acceleration in mass loss rate is found, especially for Antarctica, while Greenland mass loss, after a corresponding acceleration period, and a record mass loss in the summer of 2012, has seen a slight decrease in short-term mass loss trend. The yearly mass balance estimates, based on point mass inversion methods, have relatively large errors, both due to uncertainties in the glacial isostatic adjustment processes, especially for Antarctica, leakage from unmodelled ocean mass changes, and (for Greenland) difficulties in separating mass signals from the Greenland ice sheet and the adjacent Canadian ice caps. The limited resolution of GRACE affects the uncertainty of total mass loss to a smaller degree; we illustrate the “real” sources of mass changes by including satellite altimetry elevation change results in a joint inversion with GRACE, showing that mass change occurs primarily associated with major outlet glaciers, as well as a narrow coastal band. For Antarctica, the primary changes are associated with the major outlet glaciers in West Antarctica (Pine Island and Thwaites Glacier systems), as well as on the Antarctic Peninsula, where major glacier accelerations have been observed after the 2002 collapse of the Larsen B Ice Shelf.
KeywordsGreenland ice sheet Antarctica mass loss GRACE Envisat CryoSat
This paper is based on a presentation at the Workshop of the International Space Science Institute (ISSI), Bern, Switzerland, February 2015. The sea level “fingerprinting” plots in Fig. 1 was provided by V. Barletta. Johan Nilsson, former PhD student at DTU Space, now at NASA-JPL, provided the retracked CryoSat-2 data for Greenland. Torsten Mayr-Gürr, TU Graz, provided early access to the new ITSG-processed GRACE L2 data. Comments by Anny Cazenave and Nicolas Champollion improved the original manuscript.
- Bettadpur S (2003) GRACE level-2 gravity field product user handbook. CSR Publ. GR-03-01, University of Texas, Austin. http://podaac.jpl.nasa.gov/grace
- Forsberg, R and Reeh N (2007) Mass change of the Greenland ice sheet from Grace. In: Proceedings of the 1st international symposium of the IGFS, Harita Dergisi, Ankara, vol 18, pp 454–458Google Scholar
- Forsberg R, Sørensen L, Levinsen J, Nilsson J (2013) Mass loss of Greenland from GRACE, IceSat and CryoSat. In: Proceedings of the CryoSat workshop, Dresden, ESA Special Publication 717 paper S6-4Google Scholar
- Fretwell P, Pritchard HD, Vaughan DG, Bamber JL, Barrand NE, Bell R, Bianchi C, Bingham RG, Blankenship DD, Casassa G, Catania G, Callens D, Conway H, Cook AJ, Corr H, Damaske D, Damm V, Ferraccioli F, Forsberg R, Fujita S, Gogineni P, Griggs JA, Hindmarsh R, Holmlund P, Holt J, Jacobel RW, Jenkins A, Jokat W, Jordan T, King EC, Kohler J, Krabill W, Riger-Kusk M, Langley K, Leitchenkov G, Leuschen C, Luyendyk B, Matsuoka K, Nogi Y, Nost O, Popov S, Rignot E, Rippin D, Riviera A, Roberts J, Ross N, Siegert M, Smith A, Steinhage D, Studinger M, Sun B, Tinto B, Welch B, Young D, Xiangbin C, Zirizzotti A (2012) Bedmap2: improved ice bed, surface and thickness datasets for Antarctica. Cryosphere 6:4305–4361. doi: 10.5194/tcd-6-4305-2012 CrossRefGoogle Scholar
- Heiskanen W, Moritz H (1967) Physical geodesy. Wheeler, San FrancisoGoogle Scholar
- Klinger B, Mayer-Gürr T, Behzadpour S, Ellmer M, Kvas A and Zehentner N (2016) The new ITSG-Grace2016 release, EGU General Assembly 2016, Vienna, Austria, doi: 10.13140/RG.2.1.1856.7280Google Scholar
- Mayer-Gürr T, Zehentner N, Klinger B, Kvas A (2014) ITSG-Grace2014: a new GRACE gravity field release computed in Graz. In: GRACE Science Team Meeting (GSTM), PotsdamGoogle Scholar
- Sasgen I, van den Broeke M, Bamber JL, Rignot E, Sørensen LS, Wouters B, Martinec Z, Velicogna I, Simonsen SB (2012) Timing and origin of recent regional ice-mass loss in Greenland Earth Planet. Sci Lett 333–334:293–303Google Scholar
- Swenson SC, Chambers DP, Wahr J (2008) Estimating geocenter variations from a combination of GRACE and ocean model output. J Geophys Res Solid Earth 113(B8), Article B08410. doi: 10.1029/2007JB005338