September 11, 2013
There continues to be a persistent misperception that all glaciers in Glacier National Park, Montana will be gone by 2030, I get asked that by journalists frequently, and when I point out that is not the case, they are surprised. The number of glaciers has declined from 150 to less than 30 today, and most of those are doing poorly, however, there are a few that are retreating relatively slowly and not on the verge of disappearing. This week brings another examples from National Geographic. This post focusses on why this is not going to occur using Kintla Glacier as an example. Kintla Glacier is 8 km south of the border with Canada on the north slope of Kintla Peak and drains into Medicine Bow Creek and then Kintla Lake. All of the images from Google Earth and Landsat are oriented with south at the top. Kintla Glacier is noted by Key et al (2002) and by continuing USGS reseearch to have had an area of 1.7 km in 1966 and 1.15 km2 in 2005. This is the loss of nearly a third in 40 years. Here we examine changes from 1990 to 2013 using three Google Earth images and a Landsat image from 2013 to indicate the changes in the glacier during the last two decades. The margin of the glacier in the sequential Google Earth images from 1990 (red), 2003 (orange) and 2007 (yellow) indicate the limited retreat in this period. Retreat averages 30-40 m with a glacier length averaging 500 m. The width of the glacier changed even less. Hence, this glacier has lost 5-10% of its area from 1990 to 2007. n 1990 Jon Scurlock has some exceptional images of the glacier taken in 2009 and posted Glaciers of the American West. These images indicate a glacier that has less than ideal snowcover, but significant crevassing near the main terminus and insignificant retreat from 2007. In 2013 Landsat imagery from August indicates no major retreat. Thus, this glacier is thinning and retreating, but is not poised despite its small size to disappear by 2030.
A key indicator of a glacier that will not survive current climate for long, is retreat of the upper margin and appearance of bedrock outcrops on the upper glacier (Pelto, 2010), neither is apparent here. A indicates a cliff below the main terminus, and is a good measure of the lack of retreat from this point. Point B is the end of a buttress that has not changed significantly during the 1990-2007 period indicating a lack of change in the upper portion of the glacier. The last image is a picture of the glacier from 2007 indicating a glacier that is not about to disappear in the next twenty years. This glacier will survive beyond 2030 just as Harrison Glacier will. Other glaciers in this park that continues to lose glaciers are not going to survive as long, such as Grinnell Glacier or Sperry Glacier. All of the glaciers in the region are responding to recent climate change, but not at the same rate. Further warming will certainly eliminate all of them.