Ocean forcing drives glacier retreat in Greenland.

• Main Authors: Wood, Michael, Rignot, Eric, Fenty, Ian, An, Lu, Bjørk, Anders, van den Broeke, Michiel, Cai, Cilan, Kane, Emily, Menemenlis, Dimitris, Millan, Romain, Morlighem, Mathieu, Mouginot, Jeremie, Noël, Brice, Scheuchl, Bernd, Velicogna, Isabella, Willis, Josh K, Zhang, Hong
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: eScholarship, University of California 2021
• Subjects: Greenland; glacier; Ice Sheet; Ice Shelves
• Online Access: https://escholarship.org/uc/item/22k9s47z

The retreat and acceleration of Greenland glaciers since the mid-1990s have been attributed to the enhanced intrusion of warm Atlantic Waters (AW) into fjords, but this assertion has not been quantitatively tested on a Greenland-wide basis or included in models. Here, we investigate how AW influenced retreat at 226 marine-terminating glaciers using ocean modeling, remote sensing, and in situ observations. We identify 74 glaciers in deep fjords with AW controlling 49% of the mass loss that retreated when warming increased undercutting by 48%. Conversely, 27 glaciers calving on shallow ridges and 24 in cold, shallow waters retreated little, contributing 15% of the loss, while 10 glaciers retreated substantially following the collapse of several ice shelves. The retreat mechanisms remain undiagnosed at 87 glaciers without ocean and bathymetry data, which controlled 19% of the loss. Ice sheet projections that exclude ocean-induced undercutting may underestimate mass loss by at least a factor of 2.