October 31, 2011

Lower Fremont Glacier, Wyoming Disappearing

Posted by Mauri Pelto

The Wind River Range is host to 40 glaciers that all have retreated significantly over the last 25 years and 45 years. Of the 15 glaciers observed in detail, nine will not survive current climate (Pelto, 2008). The Lower Fremont is one of the glaciers that will not survive. A comparison of its extent from 1966 USGS map, 1994 USGS aerial photography and 2006 satellite image in Google Earth indicate the retreat. The 1966 glacier boundary is outlined in orange. . The glacier has lost 23 % of its area and the terminus has 130 retreated meters. A new lake has formed since 1994 at the terminus, and new outcrops of rock have emerged, as noted in the combined 1994-2006 image below.The key changes that indicate the glacier is not going to survive are the outcrops of rock that have emerged in the upper portion of this glacier, blue arrows. The new lake is indicated by the red arrow. The green arrows indicate the numerous firn layers exposed at the surface. Both the exposure of firn layers and the emergence of bedrock and rock through the glacier indicates the lack of a consistent and persistent accumulation zone. This indicates the glacier will not survive ((Pelto, 2010 and Pelto, 2011).