Again and again the question is asked which is the largest glacier in the world and where it is located. Numerous unofficial rankings circulate on the Internet, attracting visitors to a wide variety of regions. But the question of which one holds the record cannot be answered so easily by simply measuring length or area. An international research team has tackled the subject and taken a strictly scientific approach. The result is two ranking lists with partly surprising results.
According to the results of Ann Windnagel of the National Snow and Ice Data Center in Boulder, USA, the Antarctic Peninsula is the record holder for both individual glaciers and glacier complexes. According to the research team, the latter are glaciers that meet at ice divides such as ice caps and ice fields. “Using separate rankings for glaciers and glacier complexes, we find that the largest glacier complexes have areas on the order of tens of thousands of square kilometers whereas the largest glaciers are several thousands of square kilometers,” the team concludes in their study. The work, which also involved Dr. Matin Zemp of the University of Zurich, was published in the latest issue of the Journal of Glaciology.
The record holder for individual glaciers is the Seller Glacier with an area of 7,018 square kilometers. Also in the Antarctic Peninsula area, but on an offshore island, is runner-up Thurston Island Glacier, which at over 5,000 square kilometers is already 25 percent smaller. The arctic Malaspina glacier in Alaska is only about half as large as Seller Glacier. And the largest glacier entirely outside the polar regions is the Pio XI glacier in the southern Andes. However, if one places the boundary of the Arctic on the Arctic Circle, Skeidararjökull on Iceland is the largest glacier outside the Arctic and thus also the largest in Europe. According to the study, the total area of the ten largest individual glaciers accounts for around five percent of the total glacial area worldwide.
In the study, the team led by lead author Ann Windnagel examined not only individual glaciers, but also ice or glacier complexes that are not, however, part of the Antarctic or Greenland ice sheets. This showed that, according to their definition, the ice cap of the Antarctic Peninsula is not an ice sheet or part of the West Antarctic Ice Sheet, but is an ice cap in its own right and thus the largest glacier complex in the world, covering 80,852 square kilometers. The second-place complex covers Alexander Island at the southern end of the peninsula, and the third-place complex is again the Malaspina complex in Alaska. The Southern Patagonian Ice Field is the largest area outside the Arctic and Antarctic. The famous Icelandic Vatnajökul ice cap is still behind the Asgardfonna cap on Spitsbergen.
In order to properly classify and categorize the glaciers and ice areas, the team had to include official area measurements and their timings in addition to the boundaries that define each glacier (of which there are about 383,000 records). This is because it is common knowledge that almost the entire cryosphere, which makes up about 12.5 percent of the Earth’s surface, is in retreat. Other challenges the team identified in their study related to the research question include uncertainties in measurements of glacier boundaries, definitions of glaciers, and data quality and consistency. “A basic requirement for such a ranking is delimiting glacier boundaries based on hydrological basins as well as having a clear differentiation between glaciers and glacier complexes,” the team concludes.
Dr Michael Wenger, PolarJournal
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