Earth and Planetary Sciences (all); General Earth and Planetary Sciences
Abstract :
[en] Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay’s upper 250 m have cooled to levels not seen since the mid 1980s. Observations and modelling trace the origins of this cooling to anomalous wintertime heat loss in the boundary current that circulates around the southern half of Greenland. Longer time series of ocean temperature, subglacial discharge and glacier variability strongly suggest that ocean-induced melting at the front has continued to influence glacier dynamics after the disintegration of its floating tongue in 2003. We conclude that projections of Jakobshavn’s future contribution to sea-level rise that are based on glacier geometry are insufficient, and that accounting for external forcing is indispensable.
Disciplines :
Earth sciences & physical geography
Author, co-author :
Khazendar, Ala ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Fenty, Ian G. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Carroll, Dustin; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Gardner, Alex ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Lee, Craig M.; Applied Physics Laboratory, University of Washington, Seattle, United States
Fukumori, Ichiro; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Wang, Ou; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Zhang, Hong; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Seroussi, Hélène ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Moller, Delwyn; Remote Sensing Solutions, Barnstable, United States
Noël, Brice ; Université de Liège - ULiège > Département de géographie > Climatologie et Topoclimatologie ; Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands
van den Broeke, Michiel R. ; Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, Netherlands
Dinardo, Steven; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
Willis, Josh; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, United States
The authors acknowledge support from the following sources. A.K.: NASA’s Cryospheric Sciences Program; and the Oceans Melting Greenland mission. I.G.F., I.F., O.W. and H.Z.: NASA’s Physical Oceanography; Cryospheric Sciences; and Modeling, Analysis and Prediction programmes. C.M.L.: NSF grant ARC-1022472 and NASA’s Physical Oceanography programme. H.S.: NASA’s Cryospheric Sciences; and Modeling, Analysis and Prediction programmes; and JPL’s Research and Technology Development programme. M.R.v.d.B. and B.P.Y.N.: the Netherlands Earth System Science Centre. The authors thank JPL’s UAVSAR group for ongoing support for the processing and use of the GLISTIN-A data. The authors thank J. Gobat, A. Huxtable, B. Jokinen and E. Boget (APL-UW) and the captains and crews of R/V Knorr and R/V Atlantis for their efforts in supporting the Davis Strait array. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
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