Mapping Greenland’s mass loss in space and time

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.

GRACE, time-varying gravity, Earth system dynamics and climate change

“…Again, the inland growth and coastal ablation was observed, with an epicenter in the southeast and increasing mass losses in the northwest. This spreading of the mass loss to the northwest (illustrated in Figure 20) was later confirmed in other studies [e.g., 203,204,205] and independently by GPS stations which recorded uplift of the Earth surface in response to the diminished ice load. In the same study, Khan et al [206] also reported moderate deceleration of the southeast ice loss in 2006 based on GRACE and GPS observations.…”

Extensive retreat of Greenland tidewater glaciers, 2000–2010

“…4). GRACE analyses suggest acceleration in mass loss in the NW since late 2005 or 2007 (Chen et al, 2011;Khan et al, 2010;Schrama and Wouters, 2011;Harig and Simons, 2012;Sasgen et al, 2012), with the highest mass loss rates at the end of the period, (i.e., since 2009). In contrast, Enderlin et al (2014) showed glaciers in the NW having a slowly increasing discharge over the period with a decrease in discharge acceleration during 2006-2008 and an increase in 2008-2010.…”

Evidence of meltwater retention within the Greenland ice sheet

“…Instead, these losses are inferred from satellite gravity anomalies (Chen et al, 2011;Harig and Simons, 2012;Luthcke et al, 2006;Ramillien et al, 2006;Velicogna and Wahr, 2005), remotely-sensed elevation changes at the ice sheet surface (Krabill et al, 2004;Pritchard et al, 2009) or surface mass balance models (Box et al, 2006;Van den Broeke et al, 2009a;Ettema et al, 2009;Fettweis, 2007;Hanna et al, 2008;Mernild et al, , 2010bVernon et al, 2013). All of these methods have uncertainties when used to estimate meltwater fluxes exiting the ice sheet.…”