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Extreme Ice Survey 80°S 160°W 120°W 60°W 20°W 20°E 60°E 100°E 140°E 180° 80°S
Penn State Ice and Climate Research Center
Byrd Polar Research Center Coordinate System: World Flat Polar Quartic
Central Meridian: 0°0'0"
Figure 1. Global distribution of glaciers studied by the co-authors.
imagery that displays changes in coverage Kääb et al. (2012) used satellite laser altim- authors assess findings from six conti-
area (Gardner et al., 2013). As we shall see, etry and a global elevation model to report nents, where inquiry spans the study of ice
comparison between results determined by widespread loss of ice in the Himalayas. sheets, ice caps, and mountain glaciers.
various tools lends confidence to the find- While one recent study suggested slight The researchers at the Byrd Polar and
ings. Remote sensing is advantageous growth of the Antarctic ice sheet as an Climate Research Center (BPCRC) and
because glaciated terrain is remote and ongoing response to the increase in snow- Penn State Ice and Climate Exploration
difficult to access (Luthcke et al., 2008). fall at the end of the last ice age (Zwally et have extracted, or helped to extract, ice
Kääb (2008) also notes that spaceborne al., 2015), a study using a wider range of cores at the sites indicated. The ice cores
techniques are sustainable for global-scale analytical techniques (Shepherd et al., provide histories of annual net balance and
monitoring of glaciers because satellites 2012) indicates shrinkage at both poles. of precipitation chemistry. The Extreme
can remain operational for decades. Several additional studies as summarized Ice Survey provides extensive archives of
by Scambos and Shuman (2016) support time-lapse photography for a multitude of
These observations provide robust docu- and extend the record of Antarctic mass glaciers, which reveal changes in the lat-
mentation of ice loss. Arendt et al. (2013) loss. Jacob et al. (2012) used GRACE eral extent and thickness of ice.
reported a mass-balance for glaciers in the results to calculate global ice change of
Gulf of Alaska of -65 ± 11 Gt/a from 2003 -536 ± 93 Gt/a between 2003 and 2010 by Examples of ice loss are abundant and
to 2010 from the Gravity Recovery and summing the mass balance of twenty gla- well documented. Since 1974, investigators
Climate Experiment (GRACE), which ciated regions around the planet. Thus, at the BPCRC have monitored glaciers in
compared well with their determination of satellites are very useful for assessing South America, Africa, and Asia. In
-65 ± 12 Gt/a from the Ice, Cloud, and changes in glaciers, both regionally and Tanzania, the total surface area of the ice
land Elevation Satellite (ICESat) based over time. fields on top of Mount Kilimanjaro
upon glacier elevation changes. Kääb decreased by 88.3% from 1912 to 2013;
(2008) compared a digital elevation model Land-Based Glaciology however, the rate of retreat has recently
from the Advanced Spaceborne Thermal accelerated—from 2000 to 2013, they
Emission and Reflection Radiometer Our documentation of ice loss, like that decreased by 40%. The three remaining
(ASTER) satellite optical stereo to eleva- of other groups working on this problem, ice fields on its summit and slopes are also
tion data from ICESat and an earlier topo- integrates art with science, by focusing losing volume vertically at a rate of 0.5 m/a
graphic map to report elevation change at upon glaciologic study that is enriched (Thompson et al., 2009, 2011). In Papua,
two ice caps in eastern Svalbard of -0.55 through photography. Figure 1 displays the New Guinea, several small glaciers exist in
or -0.61 m/a between 1970 and 2002 global network of monitoring completed the vicinity of Puncak Jaya. From 1850 to
(ASTER) and 2006 (ICESat), respectively. by the co-authors’ collaborators. The 2005, their total surface area decreased
www.geosociety.org/gsatoday 5
