3.3.3: Glaciers

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While ice sheets and sea ice are restricted to the poles, glaciers occur throughout the world, even in tropical locations, where mountain ranges reach elevations high enough to allow the development of ice. For example, both New Zealand and Chile contain high-elevation mountain glaciers. The World Glacier Monitoring Service (WGMS) tracks and reports data on ‘reference’ glaciers (glaciers with greater than 30 years of documented mass-balance measurements). Mass data on these reference glaciers indicates significant degrees of glacier mass loss across the globe (Fig 3.3.3.1).

Figure \(\PageIndex{1}\): Cumulative glacier mass change for reference glaciers across the globe from 1950 to 2020 compared to each glacier’s mass value in 1976. Positive values indicate higher glacier mass, negative values indicate lower mass compared to 1976. Colored lines represent reference glaciers in different regions, while the black dotted line represents the global average across all regions. Image from WGMS 20201

In 1997, researchers at the Northern Rocky Mountain Science Center began the Repeat Photography Project to illustrate changes in glacier extent in Glacier National Park, Montana, USA through current and historical photography. The value of this project is illustrated by the highly visible change in Grinnell Glacier from 1938 to 2015 (Fig 3.3.3.2). Warming and glacier melt is so severe in this region that a 2003 study estimated that the park may be ice-free, containing not a single glacier, by the year 2030 (Hall and Fagre, 2003), though other studies have predicted some glaciers may persist as long as 2080 (Brown et al 2010).

Figure \(\PageIndex{1}\): Ice loss in Grinnell Glacier in Glacier National Park, Montana USA. Images modified from USGS2.

Image Credits

WGMS (2020, updated, and earlier reports). Global Glacier Change Bulletin No. 3 (2016-2017). Zemp, M., Gärtner-Roer, I., Nussbaumer, S. U., Bannwart, J., Rastner, P., Paul, F., and Hoelzle, M. (eds.), ISC(WDS)/IUGG(IACS)/UNEP/UNESCO/WMO, World Glacier Monitoring Service, Zurich, Switzerland, 274 pp., publication based on database version: doi:10.5904/wgms-fog-2019-12.
https://www.usgs.gov/centers/norock/science/grinnell-glacier-mount-gould?qt-science_center_objects=0#qt-science_center_objects