Ocean forcing drives glacier retreat in Greenland
Michael Wood, Eric Rignot, Ian Fenty, Lu An, Anders Anker Bjørk, M. R. van den Broeke, Cilan Cai, Emily Kane, Dimitris Menemenlis, Romain Millan, Mathieu Morlighem, J. Mouginot, Brice Noël, B. Scheuchl, I. Velicogna, J. K. Willis, Hong Zhang
Abstract
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.