Greenland Ice Sheet Retreat Leading to Island Development, by Mauri Pelto

January 14, 2014 10:20 pm0 comments

Climate change is changing the map of our world.  The changes can be distant from the cause, such as sea level rise, which is partially from melting ice sheets, on coastlines around the world.  The changes can be local as well such as is in the formation of new lakes, expansion of existing lakes or development of new islands due to glacier retreat.  The rate of Greenland Ice Sheet retreat since 2000 has been significant on nearly all outlet glaciers.  Howat and Eddy (2011) examined 210 outlet glaciers and found more than 90% had retreated, with nearly 100% retreating in the Northwest of Greenland.  An examination of glaciers on the Northwest Coast indicates the retreat is leading to the development of numerous new islands.

Here we examine three specific instances where islands have formed utilizing Landsat images from the USGS Glovis system.  McFadden et al (2011)  observed that all of the glaciers in this region experienced rapid thinning of up to ~100 m  since 2000 accompanied by retreat. Each glacier also had a coincident speed-up with a 20% acceleration for Steenstrup Glacier (McFadden et al, 2011). This is a familiar pattern with outlet glacier thinning there is less friction at the calving front from the fjord walls and the fjord base, leading to faster flow. The enhanced flow leads to increased iceberg calving, terminus retreat and further thinning, resulting in the thinning and the acceleration spreading inland. The initial thinning typically comes from a combination of basal and surface melt of the terminus tongue.

The retreat of Steenstrup Glacier from 1999 to 2013 has led to the development of islands at the former Red Head, indicated by the red arrows in both images.  The yellow dots indicate the ice front. The yellow arrow indicates a new island about to form at Cape Seddon. The connection between the ice sheet and Cape Sneddon was only 200 m in mid-August 2013, and may already have been lost.  The orange and purple arrows indicates islands still at the edge of the ice sheet, but not for long.

steenstrup 1999Steenstrup 2013

Landsat Images from 1999 above and 2013 below

A short distance northwest of Steenstrup Glacier is Rink Gletscher.  This is a smaller outlet glacier.  Here images from 2001 and 2013 indicate the development of a new island at the yellow arrow and an island that will soon form at the pink arrow.

Rink Gletscher 1999

Rink Gletscher 1999

Runk Gletscher 2013

Runk Gletscher 2013

The last example is from a large outlet glacier Kong Oscar Glacier.  Island A was barely attached to the ice sheet in 2002 and is now surrounded by water.  Island B and C are both still in contact with the ice sheet, but for how long? Kong Oscar Glacier has retreated 3 km from 2002 to 2011.  These are but three examples where the coast of  Greenland is changing.

Kong Oscar 2002

Kong Oscar 2002

Kong Oscar 2011

Kong Oscar 2011

Landsat images 2002 above and 2011 below

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