Glaciers in Peru play a major role in water availability and they also have direct implications on natural hazards such as glacial lake outburst floods (GLOFs) and/or ice avalanches, which have caused a high number of fatalities and damage to infrastructure in the last decades. Despite a noticeable effort to quantify and understand the shrinking and thawing of glaciers in Peru, there are still regions where detailed assessment is still missing.In this work, a set of remote sensing images were used to map, for the first time, the evolution of the glaciated area (from 1970 to 2018) in the Pariacacá Mountains (11º5’ S, 76º0’ W) in the Cordillera Central of Peru. The results evidenced a marked decrease of the glaciated surface, with 55.3% shrinkage since 1970 and 40% since 1987. Faster glacier retreat occurred between 1985 and the end of the 1990s, and this period was followed by a significant slowdown in shrinking rates. The differential loss of ice, depending on elevation and exposure to incoming radiation, has led to changes in spatial distribution of the glaciers. Currently, they have almost completely thawed below 5000 m a.s.l. They are mostly located in south- to west-facing aspects. Ice melting in the last decades has even affected the summit areas. Finally, the development of ablation hollows has been identified as an important driver of glacier thaw. These features are formed mainly in gentle slopes and highly irradiated zones between 5000 and 5400 m a.s.l.
This study updates information on the evolution of glacier shrinkage in
Cocuy-Güican mountains since the maximum glacier extent of the Little
Ice Age (LIA), and presents the first mass balance data of Ritacuba
glacier since 2009, that is compared to the available mass balance for
the Conejeras Glacier (Los Nevados National Park). This study also
discusses the hydrological significance of Colombian glaciers which is
still largely unknown because of the very limited information available.
Glaciers in Cocuy-Güican covered 13.2 km2 in 2019 that compared to the
127.8 km2 during the maximum LIA represents a shrinkage of 89.7%.
Glacier cover observations in 1955, 1994, 2010 and 2019, reveal that the
rate of ice loss was the largest from 1994 to 2010 (0.59 km2 yr-1) and
was then more than halved from 2010 to 2019 (0.34 km2 yr-1). This
slowdown in glacier retreat is in line with a moderate negative mass
balance measured for 2009-2019, with an accumulated loss of 1,766 mm
w.e. The progressive confinement of glaciers to higher elevation and
optimal topographic context together with a lack of recent marked
climatic anomalies, could explain that Cocuy-Güican glaciers have
temporally reached near equilibrium state condition. This is in stark
contrast with Conejeras glacier where 47,000 mm w.e. has been lost in
the same period. The available data on runoff and isotopic traces of
streamflows and precipitation suggest a primary control of precipitation
on the hydrological variability of the high elevated sites, compared to
glacier melt water.
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