Box and Decker (2011) focused on the changes in the terminus of 39 Greenland Outlet glaciers from 2000-2010. Of these 35 had experienced net loss with the collective loss of 1593 km2 over the last decade. (Box and Decker, 2011). The retreat has occurred irrespective of the different characteristics of various glaciers (Bailey and Pelto, SkS) One of the glaciers in this group is Upernavik Glacier on the NW Greenland Coast. The Upernavik Glacier refers today refers to an increasing number of separate termini that were one termini up through 1950. Jason Box of Ohio State focused on the different termini in a 2008 post, commenting on the separation of termini A and B. Here we will focus on the development of two new islands between 2002 and 2010 due to the retreat of termini C as identified by Box and Benson in the image below. There are three marginal rock islands at the icecap periphery that are consistently labeled in the images below A, B and C. In addition the two arrows indicate two former nunataks, surrounded by ice in the 2002 Landsat image (top image below), and are now becoming rock islands at the glacier front in both Landsat 2010 (middle two images) and MODIS 2011 image (bottom). In the closeup Landsat image the glacier front is indicated in orange, beyond the terminus the fjord is still filled with considerable glacier debris that has calved. The black lines in the image are the uncorrected scan lines. A 2013 Landsat image indicates changes along outlet A as island at Point X, Y and Z emerge from the ice compared to 2002.
2013 Landsat image
Google Earth currently has an image that predates the development of the new island as well. This is not the only new island in Greenland by any means. Warming Island on the east coast has gained notoriety. It is seen below in a nice August 2010 Landsat image. Box and Decker (2011) note that ice loss for Upernavik Glacier’s combined termini was 7.9 square kilometers per year from 2000-2010, in Table 2. For the 2002 to 2010 period it is evident the Upernvavik terminus C lost at least 35 square kilometers as the two new islands begin to develop, mostly between 2002 and 2008. This glacier follows the pattern of Umiamako Glacier and Jakobshavn Glacier. It also is worth noting it has a deep bed that extends well under the ice sheet as observed by Morligheim et al (2014).
Hello,
i just wanted to see more clearly, how the ice retreated between 2008 and 2011, so I made an image comparison between the August 2008 MODIS image from Russ Benson and a current August 2011 image. I realigned the Benson image to match the different projection of the current MODIS images from the NASA Rapid Response site.
In the animation it is evident, that there where two termini, which retreated the most between 2008 and 2011. One was the b terminus. It retreated around 1000-1500m in this three-year period.
Nearly the same is visible at the terminus between rock C and the neighbouring new rock island (the former nunatak). Its not clear to me, if Benson et al are counting that to the c or d terminus. The labeling in their image suggest for me, its part of the d glacier, but I’m not sure. The retreat here is also about 1km.
Here is a graphic, which shows the position of the termini in 2008 and 2011 drawn into the two MODIS images. For the two mentioned termini I would say that the loss is around 10 km² in this three-year period.
http://imageshack.us/f/853/upernarvikicestreamscro.png/
The main part of the c terminus (between rock A and the former nunataks) seems to have retreated not so fast.
In any case, it is stunning, how fast the landscape is changing up there.
greetings,
Christian
Christian I have added the latter image to the post. That is a great highlight of the B termini’s retreat. The main retreat of C had occurred by 2008.
These look like the rock outcrops we see on Mt.Baker, only when the scale is looked at they must be much larger. On the best image of the new rock islands I can’t tell just how big they are because there is no scale.
Ben Pelto
The nunataks labelled A-C are all on the order of 5 km on their long axis.
The Box and Decker (2011) paper is seriously flawed, as it contains either a large bias/error with respect to Petermann Gletscher. My objection relates to Figure-4 that suggests that Petermann Gletscher has lost over 200 km^2 of area from 2000 to 2009 when in fact the 2000-2009 area loss is no more than 10 km^2. Dr. Box and the journal’s editors are aware of this and I was asked to submit a formal comment which is forth-coming.
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global warming ???? ❓
http://mathsanimation.blogspot.com/
Indeed the warming has increased surface melt and ocean temps which increase melt of the bottom of the glacier right near the terminus, where it is afloat.