Recent variations of a debris-covered glacier (Brenva glacier) in the Italian Alps monitored by comparison of maps and digital orthophotos

Debris-covered glaciers are widespread in the mountain
chains of Asia (e.g. the Karakoram, the Himalaya and the Tien Shan). They are
also particularly common in New Zealand , in the Andes and in Alaska. Despite their
relatively common occurrence, debris-covered glaciers have
not been well studied.
In this contribution the recent evolution of Brenva debris covered glacier is analyzed by aerial photocomparisons.
The Brenva glacier tongue exhibited two main phases
during the second half of the 20th century: a strong positive
pattern of volume and thickness change between 1959 and
1983, and a less strong negative pattern between 1983 and
1999. The first phase may be explained by a drop in summer
temperature (between 1951 and 1960 the temperature was
0.658C lower at Courmayeur, close to the glacier, than the
1936–83 mean), accompanied by increased annual precipitation.
Earlier Brenva glacier results are comparable with the
general trend of the ‘clean’ Italian glaciers (they also
registered a phase of positive mass balance), but the recent
behaviour of the glacier is very different. In fact, at the end of
the 20th century, Brenva glacier and other debris-covered
glaciers such as Miage and Belvedere showed a net positive
balance because of the debris insulation effect, allowing
more ice at the lower tongue of the glacier to be conserved