title: Laser altimetry reveals complex pattern of Greenland Ice Sheet dynamics.
abstract: We present a new record of ice thickness change, reconstructed at nearly 100,000 sites on the Greenland Ice Sheet (GrIS) from laser altimetry measurements spanning the period 1993-2012, partitioned into changes due to surface mass balance (SMB) and ice dynamics. We estimate a mean annual GrIS mass loss of 243 ± 18 Gt ⋅ y(-1), equivalent to 0.68 mm ⋅ y(-1) sea level rise (SLR) for 2003-2009. Dynamic thinning contributed 48%, with the largest rates occurring in 2004-2006, followed by a gradual decrease balanced by accelerating SMB loss. The spatial pattern of dynamic mass loss changed over this time as dynamic thinning rapidly decreased in southeast Greenland but slowly increased in the southwest, north, and northeast regions. Most outlet glaciers have been thinning during the last two decades, interrupted by episodes of decreasing thinning or even thickening. Dynamics of the major outlet glaciers dominated the mass loss from larger drainage basins, and simultaneous changes over distances up to 500 km are detected, indicating climate control. However, the intricate spatiotemporal pattern of dynamic thickness change suggests that, regardless of the forcing responsible for initial glacier acceleration and thinning, the response of individual glaciers is modulated by local conditions. Recent projections of dynamic contributions from the entire GrIS to SLR have been based on the extrapolation of four major outlet glaciers. Considering the observed complexity, we question how well these four glaciers represent all of Greenland's outlet glaciers.
authors.affiliation: Department of Geology, University at Buffalo, Buffalo, NY 14260; bcsatho@buffalo.edu.
authors.forename: Beata M
authors.initials: BM
authors.lastname: Csatho
authors.affiliation: Department of Geology, University at Buffalo, Buffalo, NY 14260;
authors.forename: Anton F
authors.initials: AF
authors.lastname: Schenk
authors.affiliation: Departments of Geography and.
authors.forename: Cornelis J
authors.initials: CJ
authors.lastname: van der Veen
authors.affiliation: Department of Geology, University at Buffalo, Buffalo, NY 14260;
authors.forename: Gregory
authors.initials: G
authors.lastname: Babonis
authors.affiliation: Department of Geology, University at Buffalo, Buffalo, NY 14260;
authors.forename: Kyle
authors.initials: K
authors.lastname: Duncan
authors.affiliation: Geology, University of Kansas, Lawrence, KS 66045;
authors.forename: Soroush
authors.initials: S
authors.lastname: Rezvanbehbahani
authors.affiliation: Institute for Marine and Atmospheric Research, Utrecht University, 3584 CC Utrecht, The Netherlands;
authors.forename: Michiel R
authors.initials: MR
authors.lastname: van den Broeke
authors.affiliation: Division of Geodynamics, DTU Space, National Space institute, DK-2800 Kgs. Lyngby, Denmark; and.
authors.forename: Sebastian B
authors.initials: SB
authors.lastname: Simonsen
authors.affiliation: Department of Civil, Environmental and Geomatics Engineering, Florida Atlantic University, Boca Raton, FL 33431.
authors.forename: Sudhagar
authors.initials: S
authors.lastname: Nagarajan
authors.affiliation: Institute for Marine and Atmospheric Research, Utrecht University, 3584 CC Utrecht, The Netherlands;
authors.forename: Jan H
authors.initials: JH
authors.lastname: van Angelen
keywords: Greenland Ice Sheet; ice dynamics; laser altimetry; mass balance