Projected land ice contributions to twenty-first-century sea level rise

Projected land ice contributions to twenty-first-century sea level rise

Edwards, Tamsin L. (King’s College London)
Nowicki, Sophie (NASA Goddard Space Flight Center; University at Buffalo, State University of New York)
Marzeion, Ben (University of Bremen)
Hock, Regine (University of Alaska Fairbanks; Universitetet i Oslo)
Goelzer, Heiko (Universiteit Utrecht; Vrije Universiteit Brussel; Bjerknes Centre for Climate Research)
Seroussi, Hélène (California Institute of Technology)
Jourdain, Nicolas C. (Université Grenoble Alpes)
Slater, Donald A. (Scripps Institution of Oceanography; University of St Andrews; University of Edinburgh)
Zekollari, H. (TU Delft Mathematical Geodesy and Positioning; Vrije Universiteit Brussel; ETH Zürich; Swiss Federal Institute for Forest, Snow and Landscape Research)

2021

The land ice contribution to global mean sea level rise has not yet been predicted¹ using ice sheet and glacier models for the latest set of socio-economic scenarios, nor using coordinated exploration of uncertainties arising from the various computer models involved. Two recent international projects generated a large suite of projections using multiple models^2–8, but primarily used previous-generation scenarios⁹ and climate models¹⁰, and could not fully explore known uncertainties. Here we estimate probability distributions for these projections under the new scenarios^11,12 using statistical emulation of the ice sheet and glacier models. We find that limiting global warming to 1.5 degrees Celsius would halve the land ice contribution to twenty-first-century sea level rise, relative to current emissions pledges. The median decreases from 25 to 13 centimetres sea level equivalent (SLE) by 2100, with glaciers responsible for half the sea level contribution. The projected Antarctic contribution does not show a clear response to the emissions scenario, owing to uncertainties in the competing processes of increasing ice loss and snowfall accumulation in a warming climate. However, under risk-averse (pessimistic) assumptions, Antarctic ice loss could be five times higher, increasing the median land ice contribution to 42 centimetres SLE under current policies and pledges, with the 95th percentile projection exceeding half a metre even under 1.5 degrees Celsius warming. This would severely limit the possibility of mitigating future coastal flooding. Given this large range (between 13 centimetres SLE using the main projections under 1.5 degrees Celsius warming and 42 centimetres SLE using risk-averse projections under current pledges), adaptation planning for twenty-first-century sea level rise must account for a factor-of-three uncertainty in the land ice contribution until climate policies and the Antarctic response are further constrained.

http://resolver.tudelft.nl/uuid:a3ecb208-c4f1-49e5-ba18-409c2ee868cb

https://doi.org/10.1038/s41586-021-03302-y

2021-11-05

0028-0836

Nature: international weekly journal of science, 593 (7857), 74-82

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

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© 2021 Tamsin L. Edwards, Sophie Nowicki, Ben Marzeion, Regine Hock, Heiko Goelzer, Hélène Seroussi, Nicolas C. Jourdain, Donald A. Slater, H. Zekollari, More Authors