December 16, 2015

Greenland Fjord Going Ice Free

Posted by Mauri Pelto

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Google Earth image from 2010 of Alangordlia Fjord

At the AGU 2015 meeting a clear change from 15 years ago is the interdisciplinary nature of most research featured in most sessions.  In the glacier sessions there is physical oceanography, biology, climatology add in.  I will examine a SW Greenland Fjord, Alangordlia to illustrate this.  In 1987 Landsat image there are four glaciers reaching tidewater in the fjord and two significant glacial fed streams contributing plumes of sediment. By 2015 two of the glaciers, green arrow and pink arrow, have retreated from contact with the fjord. The glacier at the yellow arrow will lose contact with the fjord quite soon, and the glacier at the red arrow has reduced width of contact and will retreat from the fjord in the near future. A closeup using Google Earth from 2010 illustrates the terminus of each glacier, below.

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Landsat comparison image from 1987 above and 2015 below.

As glacier melt increased in Greenland after 2000, the glacier runoff would have increased along with the sediment and nutrient flux from these streams (McGrath et al., 2010).  These plumes can be seen and even quantified using satellite imagery. The fjord outflow would increase mostly in the near surface layer as the water is fresh.  This would increase the deep water inflow of salty water (Straneo et al., 2011).  The water entering the fjord would be warmer if there is no shallow sill preventing entry. With greater flow and more nutrients the biology of the system would be altered.  Peterson et al (2015) note a summer phytoplankton bloom coinciding with the increase of summer glacier runoff.  In Svalbard examination of biology in front of glaciers by (Lydersen et al, 2013) identify that kittiwakes, fulmars, ivory gulls  and glaucous gulls are common in large numbers in the so-called “brown zone”, the area in front of tidewater glaciers that is ice-free due to currents and muddy due to suspended sediments, such as in Alangordlia.  The further observe that Animals at these sites typically have their stomachs full of large zooplankton or fish and that the brown zones are also foraging hotspots for ringed seals.  If these were larger glaciers with deep bottoms, this water would enhance melting (Chauché et al, 2014).  In this case the thin glaciers would not be much affected. The glacier retreat of these minor glaciers follows the trend of major glaciers. Murray et al (2015) examined 199 tidewater glaciers and noted significant retreat of 188 of them. This resulted in a major increase in overall mass loss from Greenland, which  quadrupled from 1992- 2001 to 2001-2011, yielding a 7.5 mm net contribution to sea-level rise from 1992-2011( Moon , 2014).  The updated response is the Arctic Report Card that will be discussed today at the AGU15 Meeting h (Tedesco et al, 2015).

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2010 Google Earth of glaciers on the south side of Alangordlia
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2010 Google Earth of glaciers at the east end of Alangordlia
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Topographic map of region from NunaGIS