Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools

• Published in: Nature Geoscience
• Main Authors: Khazendar, Ala, Fenty, Ian G., Carroll, Dustin, Gardner, Alex, Lee, Craig M., Fukumori, Ichiro, Wang, Ou, Zhang, Hong, Seroussi, Hélène, Moller, Delwyn, Noël, Brice, van den Broeke, Michiel R., Dinardo, Steven, Willis, Josh
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2019
• Subjects: Earth and Planetary Sciences (all); General Earth and Planetary Sciences; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; Disko Bay; glacier; Greenland; Ice Sheet; Ilulissat; Jakobshavn
• Online Access: https://orbi.uliege.be/handle/2268/301924; https://doi.org/10.1038/s41561-019-0329-3

peer reviewed 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.