The summer of 2012 was a warm one in the Italian Alps. This has led to large losses in glacier volume and exceptional surface melting. One example of this has been the exposure via melting of a considerable amount of World War I relics. One location noted has been the Ago Di Nardis Glacier in the Trentino Mountains, where artillery ammunition is observed Image from Maffei Glauco / Trentino Italian / EPA. In this post we use Landsat imagery from 1999, 2011 and 2012 to examine the retreat of Lobbia Glacier with a small note on the retraction of Ago Di Nardis Glacier. The Lobbia Glacier is adjacent to the Mandrone Glacier that has been examined in detail by the Università di Brescia, Italy (Ranzi et al, 2010), which lost over a meter of ice thickness on average from 1999-2006. The Lobbia Glacier retreat from 1999-2010 has been observed by the Italian Glaciological Survey and found to have retreated 140 meters from 1999-2005, and 45 m from 2006-2009. In the Landsat images the red arrow indicates the retraction in glacier width of Ago Di Nardis Glacier at the 3000 meter level. The Orange dot indicates the 1999 terminus location of Lobbia Glacier. The yellow arrow indicates the expansion of a bare rock area that had been surrounded by ice in 1999 on Lobbia Glacier. The purple arrow indicates the separation of horseshoe shape glacier adjacent to Lobbia Glacier.. The glacier has a low slope and few crevasses. The combination indicates low velocity and even stagnant conditions. The slopes on the west side of the glacier, yellow arrow are not retaining snowcover and no longer feed the glacier tongue. The lack of a consistent and persistent snowcover indicates a glacier that cannot survive (Pelto, 2010), image from TecTask. The current glacier health parallels that of Dosde Glacierand Presena Glacier
The last year with a significant positive balance on the glacier was 1977, in the majority of years since 1980 the glacier has had no accumulation zone, which equates to an accumulation area ratio of zero (Carturan and Seppi, 2007). This translates to a glacier with no income of snow, but still plenty of losses via melting, which means the glacier cannot survive, and of course will drive the retreat (Pelto, 2010). Luca Carturan, University of Padova, provides both a chart of mass balance and a comparison of the glacier from 1967 to 2009, red bars indicate negative mass balance. The glacier has the longest mass balance record of any Italian glacier and the data is submitted annually to the World Glacier Monitoring Service. Carturan et al (2012) examine the mass balance distribution in more detail, in their Figure 2 the glacier is separated from its most western appendage (W), but the center part (C) is still connected to the main section (M) of the glacier, red dots are the around glacier watershed. . The images below are a series of Landsat images from 1999, 2003, 2009 and 2011. The red arrows indicate two narrow ice connections that were intact between the west-center-main part of glacier in 1999 and 2003. By 2009 the west section is not connected, and by 2011 the center connection is also gone. The deeper blue color of the glacier indicates a lack of snowcover, snowcover can be seen on the glaciers north of the ridge above the Careser Glacier. Careser Glacier fits the pattern of thinning, lack of accumulation zone and separation as seen at Presena Glacier, Dosde Glacier and Cavagnoli Glacier
Dosdè Glacier in the Dosdè-Piazzi Group of the Italian Alps has been the focus of research by the University of Milan Department of Geography in the last decade to both chronicle its retreat, examine the causes, and evaluate the impacts and potential mitigation steps. In 1954 there was a Dosdè Est, Dosdè Centrale and Dosdè Ovest glaciers with respective areas of 1.2 and 0.8 and 0.9 square kilometers. By 2003 the areas had been reduced to 0.8, 0.5 and 0.3 square kilometers. This is evident in the picture from 1932 and 2007 of the Dosdè Glacier group from Guglielmina Diolaiuti, University of Milan. I have added arrows annotating key changes Est is on the left, Centale in the middle and Ovest (labelled Ost) on the right. The purple arrow indicates the separation of two glaciers. The blue arrow indicates the change in glacier size near the top of the peak. The orange arrow notes the thinning of the glacier near the current glacier tongue. The green arrow indicates the retreat at the head of the glacier indicating thinning even in the accumulation zone. This glacier lost all of its snowcover in several recent summers including 2010, in this Google Earth view the summer of 2010 is ongoing and their are a few white patches of snowpack from the previous winter, that were then lost. This inconsistency of the accumulation zone is a sign of a glacier that cannot survive In this region at least 6 glaciers have been observed to disappear in the last 50 years. The continued decline in area and lack of accumulation zone persistence does not suggest that glaciers in this mountain massif will survive. Dosdè Est has retreated over 400 meters in the last 50 year, but of more importance to its survival is the degree of thinning apprarent from the terminus to its head. Dosdè Est has been the focus of study utilizing a covering blanket to examine its efficacy in reducing ablation as was done on Stubai Glacier in Austria. The University of Milan group reported a 43% decline in snow ablation and a 100% decline in ice ablation. The retreat of this glacier follows the trend of increasingly rapid and widespread retreat seen throughout the Italian Alps, as chronicled by the Italian Glacier Commission, which reported more than 95% of the over 100 glaciers examined retreating from 2000-2005. The smaller size and elevation range of the Dosdè Glacier group makes them more vulnerable to complete loss than Forni Glacier.