Firn on ice sheets

The Firn Symposium team, Charles Amory, Christo Buizert, Sammie Buzzard, Elizabeth Case, Nicole Clerx, Riley Culberg, Rajashree Tri Datta, Rahul Dey, Reinhard Drews, Devon Dunmire, Clare Eayrs, Nicolaj Hansen, Angelika Humbert, Athul Kaitheri, Kaitlin Keegan, Peter Kuipers Munneke, Jan T. M. Lenaerts, Stef Lhermitte, Doug MairIan McDowell, Jessica Mejia, Colin R. Meyer, Elizabeth Morris, Dorothea Moser, Falk M. Oraschewski, Emma Pearce, Sophie de Roda Husman, Nicole-Jeanne Schlegel, Timm Schultz, Sebastian B. Simonsen, C. Max Stevens, Elizabeth R. Thomas, Megan Thompson-Munson, Nander Wever*, Bert Wouters

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


Most of the Greenland and Antarctic ice sheets are covered with firn — the transitional material between snow and glacial ice. Firn is vital for understanding ice-sheet mass balance and hydrology, and palaeoclimate. In this Review, we synthesize knowledge of firn, including its formation, observation, modelling and relevance to ice sheets. The refreezing of meltwater in the pore space of firn currently prevents 50% of meltwater in Greenland from running off into the ocean and protects Antarctic ice shelves from catastrophic collapse. Continued atmospheric warming could inhibit future protection against mass loss. For example, warming in Greenland has already contributed to a 5% reduction in firn pore space since 1980. All projections of future firn change suggest that surface meltwater will have an increasing impact on firn, with melt occurring tens to hundreds of kilometres further inland in Greenland, and more extensively on Antarctic ice shelves. Although progress in observation and modelling techniques has led to a well-established understanding of firn, the large uncertainties associated with meltwater percolation processes (refreezing, ice-layer formation and storage) must be reduced further. A tighter integration of modelling components (firn, atmosphere and ice-sheet models) will also be needed to better simulate ice-sheet responses to anthropogenic warming and to quantify future sea-level rise.
Original languageEnglish
Pages (from-to)79-99
Number of pages21
JournalNature Reviews Earth & Environment
Issue number2
Early online date23 Jan 2024
Publication statusPublished - 1 Feb 2024

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