Toward the change in the dynamics of Humboldt, Northern Greenland

Abstract:

Humboldt glacier is the widest (100 km) outlet glacier in North Greenland with a potential sea level rise of 20 cm. The glacier calves tabular icebergs into Kane Basin at low speeds. Humboldt Glacier has been continuously out of balance in the last decades but started to accelerate around 2013, accompanied by enhanced thinning and faster retreat of its grounded ice front (0.6 km/yr). Its floating extension present in 1992-1996 is now gone. We present comprehensive observations of the glacier speed and elevation over the last 42 years using high-resolution SAR (ERS, Radarsat, ALOS PALSAR, Sentinel-1a/b), optical data (Landsat, Sentinel-2, PlanetScope) and historical DEMs. We identify a continuous speed up of the northern ⅓ of the ice front versus a southern ⅔ that is stable, grounded in shallow, cold waters, slow moving and not retreating. The long term speed up is modulated by a rapid 30% speed up in the summer months. The entire region has experienced a pronounced warming in air temperature and ocean temperature which enhanced surface melt water production and undercutting by the ocean waters. We investigate the possible causes of the speed up and what that tells us about the future evolution of this large, marine-based glaciers.