Ocean impact on Greenlands 79°N-Glacier (OGreen79)
The interaction between the cryosphere and the ocean is one of the main drivers for sea-level rise. Mass loss from the Greenland Ice Sheet presently accounts for a third to a quarter of global sea-level rise and the rate of mass loss is increasing. Until recently, Greenland’s glacier acceleration has been concentrated along the southeastern and western margins of the continent, while the glaciers in the northeast have been relatively stable. Amongst these “stable” glaciers is Nioghalvfjerdsbrae or ‘79°North Glacier’, the larger of two floating ice tongues fed by the Northeast Greenland Ice Stream (NEGIS) whose drainage basin contains more than 15% of the Greenland Ice Sheet area. Two recent studies reported on an acceleration of the ice flow of the 79°N Glacier and a general reduction in ice sheet elevation near the margins of Northeast Greenland. At the same time, a warming and thickening of the Atlantic water layer has been observed in the Nordic Seas (including Fram Strait).
Our proposed project aims at
- understanding the mechanisms by which the ocean circulation in Fram Strait and on the Northeast Greenland continental shelf supplies heat toward the inner shelf region and into the cavity below the floating ice tongue of the 79°N glacier,
- assessing the role of these external forcings vs. forcing arising from processes within the cavity in driving melting at the base of the ice tongue, and
- identifying the main sensitivities in this coupled ice-ocean system.
The goals will be tackled by a combination of targeted near- and far-field observations and state-of-the-art sensitivity experiments relying on innovative high-resolution numerical model simulations. The observational component is based on observations of flow speeds, hydrography and microstructure using both lowered and moored platforms and will be pursued in the framework of two research cruises with R/V Polarstern. These measurements will be supplemented with a non-invasive fine-scale survey with an autonomous underwater vehicle. The modelling component relies on the Finite Element Sea ice Ocean Model (FESOM) that has been augmented by an ice shelf component and is set up in a high-resolution configuration that addresses small-scale processes on the northeast Greenland continental shelf and in the sub-ice cavity of the 79°N glacier in the context of a global model. Together with input from our cooperation partners working on glaciology and tracer oceanography, the synergy of these components will provide a detailed picture of the processes governing the mass flux between the Greenland Ice Sheet and the Nordic Seas sector of the global ocean.
The OGreen79 project is also a member of the Focusgroup Cryosphere and Sea Level (FCS).
Publications of the OGreen79 project
Mayer, C. , J. Schaffer, T. Hattermann, D. Floricioiu, L. Krieger, P.A. Dodd, T. Kanzow, C. Licciulli, and C. Schannwell (2018), Large ice loss variability at Nioghalvfjerdsfjorden Glacier, Northeast-Greenland, Nature Communications, 9 (1), doi:10.1038/s41467-018-05180-x.
Schaffer, J., W.-J. von Appen, P.A. Dodd, C. Hofstede, C. Mayer, L. de Steur, and T. Kanzow (2017), Warm water pathways toward Nioghalvfjerdsfjorden Glacier, Northeast Greenland, J. Geophys. Res. Oceans, 122, 4004-4020, doi:10.1002/ 2016JC012462.