Several studies have observed the retreat and mass loss of
glaciers in the Andes over the last few decades (Dixon and
Ambinakudige, 2015; Gardner
et al.
, 2013; Lopez
et al.
, 2010;
Rabatel
et al.
, 2013; Rignot
et al.
, 2003). Mouginot and Rignot
(2015) observed some of the fastest flowing glaciers using In-
terferometry Synthetic Aperture Radar (
InSAR
), with velocities
up to 10 km a
-1
in the southern part of the South Patagonian
Icefields (
SPI
). A recent spatiotemporal analysis of the San
Rafael glacier using photogrammetric techniques showed a
glacial velocity up to 16 meters per day (Maas
et al.
, 2013).
Similarly, analysis based on satellite data between 1984
and 2011 in the
SPI
, showed that, there was, on an average
1.56 km retreat in 31 glaciers, with the maximum retreat more
than 6 km in the Jorge Montt, HPS12, and Upsala glaciers
(Sakakibara and Sugiyama, 2014). A gravimetric analysis us-
ing Gravity Recovery And Climate Experiment (
GRACE
) data
from 2002 through 2006 in the Patagonian Icefields reported
a mass loss rate of -24.3 ±4.3 km
3
a
-1
(Chen
et al.
, 2007). A time
series analysis comparing
ASTER
and
SRTM DEM
s by Willis
et al.
(2012) also observed a mass loss rate of about −24.4
±1.4 Gt a
−1
between 2000 and 2012 in Patagonian Ice fields,
which is equivalent to +0.067 ±0.004 mm a
−1
of sea level rise.
Likewise, another spatiotemporal analysis in the region by
White and Copland (2013) found a net loss of the extent of the
glaciers in 130 basins across the
SPI
from 1970 to late-2000.
Dixon and Ambinakudige (2015) also observed glacial retreat
in the San Quintin, HPN1, Pared Norte, Strindberg, Aco-
dado, Nef, San Quintin, Colonia, HPN4, and Benito glaciers
in the North Patagonian Icefields by analyzing
ASTER
stereo
and Landsat datasets. Lopez
et al.
(2010) recounted a maxi-
mum retreat of about 12 km in the Cordillera Darwin Icefield
between 1945 and 2005 by comparing aerial photographs,
Landsat and
ASTER
datasets. Melkonian
et al.
(2013) analyzed
ASTER
and
SRTM
data from 2000 to 2011and reported varied
thinning behavior along the north-south axis of the Cordillera
Darwin Icefield, with an average recession rate of −1.5 ±0.6 m
w.e.a
-1
, which is equivalent to a sea level rise of 0.01 ±0.004
mm a
−1
. Given these observations of the glacial changes in the
Andes, it is not surprising to note that during the twentieth
century, melting glaciers of the Andes contributed about 10
percent of the water that caused the sea level rise (Bamber
and Rivera, 2007; Rignot
et al.
, 2003; Rivera
et al.
, 2002).
Although many glaciers are retreating in the Andes, some
glaciers have shown a positive mass budget. Schaefer
et al.
(2014) showed a progressive surface mass balance from 1975
to 2011 in the South Patagonian Icefield. Masiokas
et al.
Figure 1. Current state of three glaciers in Sothern Andes.
812
October 2016
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
