21st century changes in ice flow dynamics of Greenland’s marine-terminating peripheral glaciers

Abstract:

Despite covering only ~5% of Greenland’s total land area, peripheral glaciers and ice caps (GICs) in Greenland that are dynamically disconnected from the Greenland Ice Sheet are estimated to have contributed up to 20% of the island’s ice mass loss. Located along the coast, many GICs originate at relatively high elevations and terminate in the ocean, making them acutely sensitive to both atmospheric and oceanic climate forcings. Although previous studies have used atmospheric models to examine Greenland GIC surface mass balance changes over the last few decades, the effects of recent climate forcings on glacier dynamics and resulting mass loss remain largely unknown.

Here we use the ITS_LIVE glacier velocity time series from 1985-2018, glacier surface elevations from the GIMP DEM from ~2008 and the ArcticDEM from ~2018, and Landsat-derived terminus change data from 2000-present to analyze dynamic change for 641 marine-terminating peripheral glaciers and ice caps in Greenland. Specifically, we identify changes in terminus position, ice flow velocity, and surface elevation to elucidate regional and temporal trends in dynamic glacier behavior. Results show that while many GICs retreated, accelerated, and thinned in the early 21^st century—as has been observed broadly across the Arctic—others slowed and advanced. The timing of onset and the magnitude of glacier retreat and acceleration varied both regionally and between adjacent fjords, highlighting the effects of both regional climate variation and small-scale geometric and topographic controls on glacier dynamics.