Glacial Retreat in Northern and Southern Patagonian Icefields, Argentina & Chile

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Summary:

The Northern and Southern Patagonian Icefields straddle the southern border of Chile and Argentina. Together, they represent one of the most extensive concentrations of non-polar ice in the world. The rates of thinning and calving within the icefields are increasing as a whole, which may result in a variety of unwanted consequences within this environmentally sensitive region.

Critical Statistics:
  1. The Patagonian Icefields are the largest non-polar icebodies in the southern hemisphere. The Southern Patagonian Icefield is roughly three times larger than the Northern Patagonian Icefield (Chen et al. 2007).

  2. As of 2001, the Northern Patagonian Icefield had a total ice area of 3,953 sq. km., which represented a decrease of 140 +/- 61 sq. km. Since 1979, 62 percent of the total area of change occurred along the western margin of the icefields (Rivera et al. 2007).

  3. One of the highest incidences of glacial area loss in the Patagonian Icefields was experienced by the San Quentin Glacier, which lost 33 sq. km. of ice between 1979 and 2001 despite experiencing a brief advancement between 1991 and 1994 (Rivera et al. 2007).

Causes:
  1. Climatic forces such as increasing temperature and shifting precipitation patterns are leading to increased glacial melting and thinning. Between 1998 and 2001, Bamber et al. 2007 observed a thinning rate three times higher than the snow accumulation rate for the Chico Glacier in the Southern Patagonian Icefield.

  2. Higher rates of glacial calving are occurring around icefield edges due to the decreasing elevation and changing geometry of these frozen surfaces (Raymond et al. 2005).

Impacts:
  1. Many populations that reside in the arid regions of the central and southern Andes are dependent upon water supplies from melting glaciers, such as those found within the Patagonian Icefields. Excessive melting may lead to water shortages that could affect millions of people (Coudrain et al. 2005)

  2. It is estimated that glacial melting within the Andes mountain range has contributed up to 10 percent of total sea level rise during the 20th century (Bamber et al. 2007).

  3. The risk for potential flooding may increase due to unpredictable meltwater discharges and glacial lake formation.

What is Next:
  1. Using data derived from the Gravity Recovery and Climate Experiment (GRACE) mission, it is estimated that total melting within the Patagonian Icefields will translate to an ice thickness loss of approximately 1.6 meters per year (Chen et al. 2007).

  2. Continued monitoring and study of the icefields are critical, as there is a lack of reliable data for these areas.Remotely sensed data may prove to be particularly useful due to the limited accessibility within the Patagonian region (Rivera et al. 2007).

Citations:
  1. Bamber J., and A. Rivera 2007. A review of remote sensing methods for glacier mass balance determination. Global and Planetary Change 59: 138-148.

  2. Chen, J., C. Wilson, B. Tapley, D. Blankenship, and E. Ivins 2007. Patagonia Icefield melting observed by Gravity Recovery and Climate Experiment (GRACE). Geophysical Research Letters 34: 1-6.

  3. Coudrain,A., B. Francou, and Z. Kunzewicz 2005. Glacier shrinkage in the Andes and consequences for water resources-Editorial. Hydrologic Sciences Journal 50: 925-932.

  4. Raymond, C., T. Neumann, E. Rignot, K. Echelmeyer, A. Rivera, and G. Casassa 2005. Retreat of Glacier Tyndall, Patagonia, over the last half century. Journal of Glaciology 51: 239-247.

  5. Rivera, A., T. Benham, G. Casassa, J. Bamber, and J. Dowdeswell 2007. Ice elevation and areal changes of glaciers from the Northern Patagonian Icefield, Chile. Global and Planetary Change (forthcoming).