romanzof mountain glacier retreat – From a Glaciers Perspective

Slender Glacier is not an official name, but a well suited name to this glacier in the Romanzof Mountains of the Brooks Range of Northern Alaska. It is adjacent to the Okpilak Glacier and drains into the Okpilak River, which is host to arctic grayling. Here we examine Landsat imagery from 1992-2014 to identify changes. U-Alaska-Fairbanks has an ongoing program in the nearby Jarvis Creek Watershed examining in part how will the anticipated future increase in glacier wastage and permafrost degradation affect lowland hydrology. Matt Nolan (U-AK-Fairbanks) reports on changes of nearby McCall and Okpilak Glacier. These glacier have suffered increased mass loss since 1990 as a result of an increase in the equilibrium line altitude that has reduced accumulation area and is indicative of increased ablation (Delcourt al , 2008)

USGS 1951 map

In 1992 the glacier extended downvalley to the red arrow at 1530 m. The glacier also received contribution from a tributary glacier at Point A. By 2002 the glacier had receded a short distance from the red arrow and still received input from the tributary glacier at Point A. By 2013 the glacier had receded to the yellow arrow 1100 meters from the 1992 terminus position, and now terminates at an altitude of 1675 m. The tributary glacier is no longer connected to Slender Glacier at Point A. The percent of snowcover is better than on Okpilak Glacier immediately to the west, or East Okpilak Glacier to the southeast. The first tributary entering the glacier on the east side is also disconnecting from Slender Glacier. In 2014 the Landsat image is after a light snowfall that has endured only on the glacier ice, helping outline the glaciers. The continued decline in retained snowfall and contributed snowfall from tribuatry glaciers will lead to an even more slender glacier.

1992 Landsat Image

2002 Landsat Image

2013 Landsat Image

2014 Landsat Image

Google Earth images from 2006 and 2012 indicate a rapid retreat of the thin main terminus, and the loss of contact with the tributary glacier at Point A. The retreat is similar to that of Fork Glacier and Romanzof Glacier in the same region. The retained snowcover in 2012 is minimal on Slender Glacier and its tributaries. Tributary A lost almost all snowcover in 2012 and 2013 suggesting a lack of a consistent accumulation zone, which a glacier cannot survive without (Pelto, 2010)

2006 Google Earth Image and 2012 Google Earth image

In the Romanzof Mts. Brooks Range, Alaska McCall Glacier and Okpilak Glacier have been the main focus of research. These glaciers are much smaller than glaciers in southern Alaska, as the region has much more limited amounts of snowfall. The University of Alaska-Fairbanks have focused on McCall Glacier average rate of thinning increased between 1956–93 and 1993–2002, averaging 0.4 m/year for the entire period. The primary region of thinning was the lower third of the glacier below 1700 meters (Nolan et al, 2005). The glacier had retreated 800 meters from the Little Ice Age moraine by 2000 (Nolan et al, 2005). The Equilibrium Line Altitude has risen from 2050 in the 1970’s to 2250 m recently, leading to continued and more rapid losses in ice volume (Delcourt et al, 2009). Okpilak Glacier had retreated 2 km from its Little Ice Age moraine by 2006.

In this post we examine the Romanzof Glacier. The first image indicates the various tributaries feeding into the main valley glacier, burgundy arrows, the reach of well developed stream channels, green arrows. The red line is the map terminus and the yellow line the 2009 terminus. The map is the USGS topographic map from 1956 aerial photographs This glacier has retreated 1300 meters from its 1956 mapped position and 1900 meters from its Little Ice Age moraine, blue line in first image below. The glacier remains 5 km long, having lost 25% of its length in the last 50 years. The rate of ice loss like on McCall Glacier has accelerated. A view of the middle of the ablation zone indicates some well developed stream channels, green arrows. Channels like this take multiple years to form and indicate limited glacier velocity. Closer to the terminus the stream channels are even larger, green arrows. The streams have matured developing meanders, this tends to occur only where the surface is stagnant. This indicates the lower 1200-1500 meters of the glacier is stagnant and melting away quickly. In addition there are some ridges of ice cored moraine indicating that the bare ice is melting faster than the ice under the moraine debris, violet arrows. The bluish arrows indicate where the subglacial streams have emerged from beneath the ice indicating the terminus.