Sep 14, 2016

Separation of Manhattan Is. sized ice shelf pieces from 79 Glacier far northwestern Greenland - Professor Jason E. Box

Hovgaard Øer
Professor Jason E. Box

We observed that between 14 Aug., 2015 and 3 September 2016, a marine-terminating tributary of the 79 fjord glacier, the Spalte Glacier flowing into Dijmphna Sound has detached and area (more than 95 km2) roughly the area of Manhattan Is.

The detachment of the ice shelf fragment appears to be nearly 100% complete.

The floating ice shelf fragment appears to have split into more than one piece already. But the main fragment have not floated away yet. I expect that will happen this year or next.

The fracturing and detachment is partly due to glacier dynamics (flow, stress, strain, pre-existing fractures).

Whether the ice shelf detaching is the consequence of the record warm ‘summer’ (June through August) observed at the DMI Danmarkshavn meteorological station (332 km to the south) is an obvious question.

Using Danish Meteorological Institute air temperature data c/o John Cappelen, the absolute summer temperature at Danmarkshavn was +4.9 C, producing a +2.3 C anomaly from the 1981-2010 “normal” period having temperature +2.6 C.

At Station Nord (220 km to the north) July temperatures were +1.9 C above the 1981-2010 period. Absolute July temperature at Station Nord was +5.9 C, producing a +1.9 C anomaly from the 1981-2010 ‘normal’ period having temperature +4.0 C). The Station Nord summer average temperature was +3.1. Normal is +2.3. So the Station Nord summer temperature anomaly was +0.8 C.

With a few exceptions, marine terminating outlets of the Greenland ice sheet have been retreating in recent decades. Box and Hansen (2015) surveyed 45 of the widest Greenland glaciers, which between 1999 and 2015 collectively lost an area of 1799 square km.