COMPARISON OF GRACE DERIVED GREENLAND MASS WASTING TO NEAR SURFACE TEMPERATURE FROM MERRA-2 REANALYSIS

Abstract

Melting ice from the Greenland Ice Sheet has accounted for an increasing percentage— now estimated at 25%—of rising global mean sea-level since the early 1990s. As recently as 2016, gravimetric and altimetric studies of Greenland melting rates found increasing rates of ice loss, which have not been borne out in GRACE gravimetric observations over the last few years (2015–2017). I investigate the correlations of atmospheric variables from MERRA-2 cli- mate model reanalysis to show the ways in which temperature over the Greenland Ice Sheet has changed over the MERRA-2 (1980–) and GRACE (2003–2017) records. Our results not only confirm that temporal and spatial changes in GRACE derived mass loss are coincident with changes in near surface temperature, but demonstrate some of the limitations in GRACE spatial resolution, and contextualize recent variability in ice loss within the variability and long term trend of Greenland temperature. As Greenland Ice Sheet melting continues to be more unpre- dictable than early GRACE studies may have foreseen, context is extremely important in both interpreting and communicating trends in ice loss.