Southeast Greenland’s marine-terminating peripheral glaciers underwent synchronous retreat in 2016 in response to ocean-forcing

Abstract:

The mass balance of marine-terminating glaciers in Greenland responds rapidly to changes in the regional atmospheric and oceanic conditions. Synchronous glacier retreat driven by atmospheric and oceanic forcing has been observed previously for the ice sheet’s outlet glaciers in southeastern Greenland. We observe synchronous retreat in southeast Greenland’s peripheral glaciers (i.e. glaciers independent from the Greenland Ice Sheet) using time series of glacier terminus positions. These time series were generated from an automated terminus position detection method adapted from the 2D Wavelet Transform Modulus Maxima (WTMM) segmentation method and applied to the Landsat-8 record of cloud-free images (2013-2020) for 53 peripheral glaciers along southeast Greenland. The analysis of these time series suggests that 23% of these glaciers underwent anomalous terminus retreat in the 2016 melt season that was 1.5 times the average seasonal retreat from 2013-present while 10% experienced multi-year retreat from 2016 onwards. Analysis of regional ocean temperatures from NASA’s Oceans Melting Greenland dataset and surface runoff from the Regional Atmospheric Climate Model (RACMO) suggests that the synchronous glacier retreat is driven by subsurface ocean warming as well as increased subglacial discharge of surface meltwater in 2016. Insights into the dynamics controlling widespread retreat of these peripheral glaciers’ is critical for estimating their contribution to Greenland’s total ice mass loss.