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into three smaller bodies, decreasing its area from 47.6 hectares in 1955 to 19.7
hectares in 2021, that is, a loss of surface area of 41% in 66 years.
Figure 1. Annual mass balance (m water equivalent) at Echaurren Norte Glacier.
Mechanisms of positive feedback
Positive feedback mechanisms amplify the reduction of snow and ice. The main
one is the albedo effect or reflectivity of snow and ice. Indeed, snow (with an
albedo that can reach almost 100%) and, to a lesser degree, ice (albedo of 30%
to 50%) are the whitest elements in nature, reflecting a large proportion of solar
radiation. Thus, it is essential to wear dark glasses in these snowy environments.
With increasing temperatures, the snow albedo decreases, with snow areas
absorbing more solar radiation and heating more, resulting in a higher melting.
This phenomenon is more exacerbated when the retreatment of snow cover and
glaciers exposes the soil and underlying rock, sometimes with the presence of
liquid water, whose albedo can even reach values less than 10%. The final effect
results in much larger solar radiation absorption that preferentially heats the
local and regional climate in high mountain ranges and polar zones, contributing
significantly to the loss of snow and ice.
The second positive feedback occurs due to the increment of particulate matter
resulting from the deglaciation of mountain ranges and polar areas. Part of the