Cloud microphysics and circulation anomalies control differences in future Greenland melt

Stefan Hofer*, Andrew J. Tedstone, Xavier Fettweis, Jonathan L. Bamber

*Corresponding author for this work

Research output: Contribution to journalLetter (Academic Journal)peer-review

15 Citations (Scopus)

Abstract

Recently, the Greenland Ice Sheet (GrIS) has become the main source of barystatic sea-level rise1,2. The increase in the GrIS melt is linked to anticyclonic circulation anomalies, a reduction in cloud cover and enhanced warm-air advection3–7. The Climate Model Intercomparison Project fifth phase (CMIP5) General Circulation Models (GCMs) do not capture recent circulation dynamics; therefore, regional climate models (RCMs) driven by GCMs still show significant uncertainties in future GrIS sea-level contribution, even within one emission scenario5,8–10. Here, we use the RCM Modèle Atmosphèrique Règional to show that the modelled cloud water phase is the main source of disagreement among future GrIS melt projections. We show that, in the current climate, anticyclonic circulation results in more melting than under a neutral-circulation regime. However, we find that the GrIS longwave cloud radiative effect is extremely sensitive to the modelled cloud liquid-water path, which explains melt anomalies of +378 Gt yr–1 (+1.04 mm yr–1 global sea level equivalent) in a +2 °C-warmer climate with a neutral-circulation regime (equivalent to 21% more melt than under anticyclonic circulation). The discrepancies between modelled cloud properties within a high-emission scenario introduce larger uncertainties in projected melt volumes than the difference in melt between low- and high-emission scenarios11.

Original languageEnglish
Pages (from-to)523-528
Number of pages6
JournalNature Climate Change
Volume9
Issue number7
Early online date24 Jun 2019
DOIs
Publication statusPublished - 1 Jul 2019

Structured keywords

  • GlobalMass

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