Journal Article

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

Chambers, Christopher, Breedam, Jonas Van, Bliss, Andrew, Fettweis, Xavier, Fujita, Koji, Rounce, David R., Winkelmann, Ricarda, Maussion, Fabien, O’Neill, James F., Kraaijenbrink, Philip, Rückamp, Martin, Gollege, Nicolas R., Pattyn, Frank, Huybrechts, Philippe, Champollion, Nicolas, Hoffman, Matthew J., Nias, Isabel, Wal, Roderik van de, Seroussi, Hélène, Agosta, Cécile, Lowry, Daniel P., Larour, Eric, Little, Christopher M., Smith, Robin S., Humbert, Angelika, Leguy, Gunter R., Marzeion, Ben, Goelzer, Heiko, Dumas, Christophe, Schlegel, Nicole-Jeanne, Immerzeel, Walter, Shafer, Courtney, Edwards, Tamsin L., Martin, Daniel F., Aschwanden, Andreas, Radić, Valentina, Pelle, Tyler, Slater, Donald A., Barthel, Alice, Jourdain, Nicolas C., Gladstone, Rupert, Anderson, Brian, Hattermann, Tore, Shannon, Sarah, clec'h, Sebastien Le, Tarasov, Lev, Simon, Erika, Calov, Reinhard, Trusel, Luke D., Alexander, Patrick, Quiquet, Aurélien, Cullather, Richard, Asay-Davis, Xylar, Price, Stephen F, Zhang, Tong, Malles, Jan-Hendrik, Turner, Fiona E., Gregory, Jonathan M, Nowicki, Sophie, Huss, Matthias, Felikson, Denis, Ze

2021

Overview

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 models2,3,4,5,6,7,8, 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 scenarios11,12 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.

• Publisher: Nature Research,Nature Publishing Group UK,Nature Publishing Group,Nature
• Subject: 704/106/125 / 704/106/694/1108 / 704/106/694/2786 / Antarctic climate / Antarctic ice / Climate and Earth system modelling / Climate change / Climate models / Climate policy / Coastal flooding / Computer models / Cryospheric science / Earth Resources And Remote Sensing / Earth sciences & physical geography / Economic models / Emissions / Environmental policy / Estimates / Flooding / Glaciers / Global warming / Greenhouse gases / Humanities and Social Sciences / Ice / Ice accumulation / Ice sheets / Ice shelves / Land ice / Life Sciences / Mathematical models / Mean sea level / Median (statistics) / multidisciplinary / Numerical Analysis / Paris Agreement / Physical, chemical, mathematical & earth Sciences / Physique, chimie, mathématiques & sciences de la terre / Projection and prediction / Risk aversion / Science / Science (multidisciplinary) / Sciences de la terre & géographie physique / Sea level / Sea level rise / Simulation / Snow / Snow accumulation / Snowfall / Statistical analysis / Temperature / Uncertainty