Irik Glacier flows down the southeast flank of Mount Elbrus, the highest peak in the Caucasus Mountains of Russia, red arrow on map points to current terminus of Irik Glacier, top image. The map terminus extended 1 kilometer further down the mountain. The glacier currently begins at 5000 m and descends to 2800 m, bottom image orange arrows indicate main accumulation areas, this compares to a terminus elevation of 2600 meters on the map.A decrease of area of glaciers of the Central Caucasus by 16% in the last 40 years is reported, on Elbrus the loss has been 8 % Russian Academy of Sciences National Geophysical Committee (2011). August 1998 (Top) and 2010 image (bottom) indicate the snowline on Irik Glacier, orange arrows and the glacier terminus blue arrows. The fraction of the glacier that is snowcovered is the accumulation area ratio (AAR), typically a glacier needs an AAR of 0.5-0.65 at the end of the melt season in September to be in equilibrium. For the nearby Djankuat Glacier, where annual mass balance data is reported to the World Glacier Monitoring Service, the AAR value for equilibrium is reported as 0.55. For Irik Glacier in 1998 and 2010 the AAR is 32 and 28 respectively and this is still with several weeks of melting. By the end of the melt season both would be below 0.3. The result of consistent negative balances is glacier retreat. For Irik Glacier the retreat from 1998 (top) to 2010 (bottom) is 600-700 meters, note blue arrows indicating terminus location and red arrow indicating a small rise on the southwest side of the glacier that the glacier used to wrap around, but no longer does. In a Google Earth image from 2009 the lower of the glacier is narrow and uncrevassed, this is a section that is quickly melting away. The orange arrows point out the lateral moraines from the Little Ice Age, the blue arrow the 1998 terminus and the red arrow the terminus in 2010. Irik Glacier must retreat to attempt to reestablish equilibrium with climate warming that has reduced the accumulation area. At present the lower 300 meters of the glacier is not crevassed and will melt away. Above that point the glacier is crevassed and vigorous in its flow.
Published by mspelto
Professor of Environmental Science at Nichols College in Massachusetts since 1989. Glaciologist directing the North Cascade Glacier Climate Project since 1984. This project monitors the mass balance and behavior of more glaciers than any other in North America View all posts by mspelto