Which are the largest glaciers in the world outside the ice sheets?

Glacier monitoring has been internationally coordinated for more than 125 years. Despite this long history there is no unambiguous answer to the popular question: which are the world’s largest glaciers?

In this study, we present a first scientific assessment of the largest glaciers in the world – distinct from the two ice sheets in Greenland and Antarctica – and in the 19 regions used for the current Randolph Glacier Inventory. Ranking glaciers by size is non-trivial since it depends on how an individual glacier is defined and mapped. It is also important to differentiate between individual glaciers and glacier complexes, which are contiguous glaciers that meet at ice divides and might form an ice cap or ice field.

We find that the largest glacier complexes cover areas larger than ten thousand square kilometres, whereas the largest individual glaciers cover up to several thousand square kilometres. The world’s largest glaciers and glacier complexes are located on the Antarctic Peninsula, on sub-Antarctic Islands, in the Arctic, and in Patagonia. As such, the largest glacier complexes cover areas the size of smaller countries (e.g., Switzerland or Austria) or of smaller US states (e.g. New Jersey or South Carolina), but are still orders of magnitudes smaller than the Greenland and Antarctic Ice Sheets.

In addition, we show that the ranking of glaciers requires not only clear definitions but depends on the availability, quality, and consistency of digital glacier outlines at global scale. Corresponding additional metadata are required in the available inventories to fully automate a glacier ranking by area, and to extend such a study to rankings by length, volume/mass, and other parameters.