Geography of Glaciers

by

Shrinidhi Ambinakudige

• LAST REVIEWED: 14 April 2017
• LAST MODIFIED: 26 July 2017
• DOI: 10.1093/obo/9780199874002-0098

Introduction

A glacier is defined is a mass of ice on land surface that moves under its own weight. It forms when snow accumulation exceeds ablation in a typical year. Snowfall, wind drift, avalanches, freezing rain, and meltwater in the snow pack cause accumulation. Ablation is caused by melting, sublimation, wind erosion, loss of ice by avalanche, or calving of icebergs. Valley glaciers are long and narrow and flow down a valley. The glaciers that are spread out in all directions from a central dome are called ice caps if they are small, and ice sheets if they are large. Glaciers hold about 75 percent of the world’s freshwater. Current glacier extents are out of balance with current climatic conditions. The sum of all processes that add mass to a glacier and remove mass from it over a hydrological cycle is called glacier mass balance. Glacier mass balance is a direct response of a glacier to climatic conditions and is a key indicator of climate change. Mass balances of the Greenland ice sheet and the Canadian Arctic have seen severe loss in recent years. Glaciers in Iceland, Svalbard, and Norway have retreated substantially and continue to retreat. A few glaciers in this region have increased in extent over time. In the Himalayas, loss rates in glacial areas have accelerated since the 1990s. Debris cover has increased in many valley glaciers in the Himalayas. Glaciers in China also have shown marked shrinkage. In the western Himalayas, especially in Afghanistan, many glaciers are shrinking. However, in the Karakoram, some glaciers appear to be advancing and surging. Andean glaciers, which account for about 99 percent of tropical ice cover, have shown a remarkable loss in ice area, and a similar retreating trend is seen throughout the world. Retreating glaciers can also pose significant hazards to people. Glacial melting and retreat often lead to the formation of new glacial lakes, the expansion of existing moraine-dammed lakes, and the potential for glacial lake outburst floods (GLOF). The link between the cryosphere dynamics and global warming is not simple; controversy still exists over how the ice shelves and glaciers are coupled to the warming climate. It could be the warming atmosphere and a concomitant increase in melting, or it could be due to warming of the ocean and changes in oceanic circulation and thermal attack on ice shelves. The National Snow & Ice Data Center, the World Glacier Monitoring Service, and the Global Land Ice Measurements from Space (GLIMS) projects provide glacier-related spatial and temporal data.

General Overviews

Cuffey and Paterson 2010 provides basic physical principles underlying the behavior and characteristics of glaciers. Hooke 2005 explores basics of glaciology and also provides sophisticated mathematical concepts in modern glaciology. More recently, van der Veen 2013 provides an excellent introduction to glacier dynamics and is a good reference for quantitative glaciology. Kargel, et al. 2016 focuses on the complexities of glaciers in all areas as documented via satellite observations. It examines the range of measurement methods and remote sensing products to study the world’s glaciers and ice caps. Another good source on all aspect of glaciers is Singh, et al. 2011. It contains peer-reviewed essays on snow, ice, or glacier research, including detailed reviews of glacier mass balance, climate change, glacial lake outburst floods, etc. Vaughan, et al. 2014 provides the current status of cryosphere research and climate change for the fifth assessment report of the Intergovernmental Panel on Climate Change. Abundant research papers on glaciers and climate change have been published in recent years. While there are several studies on glaciers of the European Alps and Greenland, studies on glaciers in other regions have increased only in recent decades. The authors of Hagen and Liestøl 1990 noticed the steady decrease in ice masses in Svalbard. Ageta and Higuchi 1984 is an early work on mass balance in the Himalayan range. Remote-sensing approaches to studying glaciers have become very popular due to the inaccessibility of many glaciers in the world. The authors of Kääb, et al. 2012, using differences in laser altimetry and radar measurement data, identify glacial thinning across the Hindu Kush and Himalayas and thickening of ice in the Karakoram Range. In the Greenland ice sheet, satellite remote-sensing techniques, such as radar interferometry and repeat pass tracking of surface features, are being used to study changes in glaciers. Kargel, et al. 2012 reviews published estimates of the local and ice-sheet-wide mass balances in Greenland. The authors also highlight some erroneous public ideas about changes in the Greenland ice sheet. Although there are few exceptions, both aircraft laser altimetry and satellite gravity-based measurements generally indicate that for the most part the glaciers of North America are retreating.

• Ageta, Yutaka, and Keiji Higuchi. “Estimation of Mass Balance Components of a Summer-Accumulation Type Glacier in the Nepal Himalaya.” Geografiska Annaler: Series A, Physical Geography 66.3 (1984): 249–255.

  DOI: 10.2307/520698

  One of the earliest mass balance studies in the Himalayan region. Compares mass balance of summer accumulation–type glaciers with winter accumulation–type glaciers.

• Cuffey, Kurt M., and William S. B. Paterson. The Physics of Glaciers. 4th ed. Burlington, MA: Butterworth-Heinemann/Elsevier, 2010.

  This is a basic textbook on glaciers that explains the physical principles underlying the functioning of glaciers, the relation between ice sheets and global climate, the role of ice in current and future global warming, the ice sheet as an archive of environmental parameters, and many other concepts.

• Hagen, Jon Ove, and Olav Liestøl. “Long-Term Glacier Mass-Balance Investigations in Svalbard, 1950–88.” Annals of Glaciology 14 (1990): 102–106.

  DOI: 10.1017/S0260305500008351

  This is one of the important and early studies on long-term glacier mass balance. The authors analyzed the trend in the Svalbard Islands and found that the ice masses have been steadily decreasing during the study period.

• Hooke, Roger LeB. Principles of Glacier Mechanics. 2d ed. Cambridge, UK: Cambridge University Press, 2005.

  DOI: 10.1017/CBO9780511614231

  A useful source for students, describing various concepts in glaciology. Explains sophisticated mathematical concepts in modern glaciology, such as mass balance, flow of crystalline material, glacier velocity, water flow and geomorphic implications, stress and deformation, and response of glaciers to changes in mass balance.

• Kääb, Andreas, Étienne Berthier, Christopher Nuth, Julie Gardelle, and Yves Arnaud. “Contrasting Patterns of Early Twenty-First-Century Glacier Mass Change in the Himalayas.” Nature 488.7412 (2012): 495–498.

  DOI: 10.1038/nature11324

  The authors use laser altimetry and radar measurement data to identify glacial thinning and thickening across the Himalayan and Karakoram ranges. A good study indicating that glacial changes are not uniform everywhere.

• Kargel, Jeffrey S., Andreas Peter Ahlstrøm, Richard B. Alley, et al. “Brief Communication: Greenland’s Shrinking Ice Cover; ‘Fast Times’ but Not That Fast.” The Cryosphere 6.3 (2012): 533–537.

  DOI: 10.5194/tc-6-533-2012a

  Paper was written in response to erroneous maps and claims about the shrinkage of the Greenland ice sheet in the Times Comprehensive Atlas of the World, 13th edition (London: Times Books, 2011). The paper shows the accurate maps of ice extent, on the basis of 1978–1987 aerial surveys and moderate resolution imaging spectroradiometer (MODIS) imagery.

• Kargel, Jeffrey S., Gregory J. Leonard, Michael P. Bishop, Andreas Kääb, and Bruce H. Raup, eds. Global Land Ice Measurements from Space. Berlin: Springer-Praxis, 2016.

  An international effort of researchers led to the compilation of this report on the global status of glaciers. In thirty-three chapters, the authors depend heavily on multispectral satellite imagery and exploit the unique optical properties of snow and ice to examine the world of changing glacier and its climatic context.

• Singh, Vijay P., Pratap Singh, and Umesh K. Haritashya, eds. Encyclopedia of Snow, Ice and Glaciers. Encyclopedia of Earth Sciences. Dordrecht, The Netherlands: Springer, 2011.

  DOI: 10.1007/978-90-481-2642-2

  The encyclopedia is divided into 463 articles, 64 of which constitute major review essays on an area of snow, ice, or glacier research. There are also 217 mini-entries and 182 intermediate-length entries. An e-version of the book is also available.

• van der Veen, Cornelis J. Fundamentals of Glacier Dynamics. 2d ed. Boca Raton, FL: CRC, 2013.

  DOI: 10.1201/b14059

  Introduced with a chapter on the most-important mathematical tools required in understanding and modeling glacial dynamics, this book is an excellent resource for students of glaciology.

• Vaughan, D. G., J. C. Comiso, I. Allison, J. Carrasco, et al. “Observations: Cryosphere.” In Climate Change 2013: The Physical Science Basis; Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by Thomas F. Stocker, Dahe Qin, Gian-Kasper Plattner, et al., 317–382. Cambridge, UK: Cambridge University Press, 2014.

  The fifth assessment report of the Intergovernmental Panel on Climate Change that provides the current status of cryosphere research and climate change. With the improved observational technology, and improved measurement of changes and trends in cryosphere, this report gives the status of all aspects of the cryosphere.