How much will polar ice sheets add to sea level rise?

Date:
September 17, 2020
Source:
CNRS
Summary:
Over 99% of terrestrial ice is bound up in the ice sheets covering
Antarctic and Greenland. Even partial melting of this ice due
to climate change will significantly contribute to sea level
rise. But how much exactly? For the first time ever, glaciologists,
oceanographers, and climatologists from 13 countries have teamed
up to make new projections.



FULL STORY ==========================================================================
Over 99% of terrestrial ice is bound up in the ice sheets covering
Antarctic and Greenland. Even partial melting of this ice due to climate
change will significantly contribute to sea level rise. But how much
exactly?

==========================================================================
For the first time ever, glaciologists, oceanographers, and climatologists
from 13 countries have teamed up to make new projections. Their modelling efforts, involving CNRS and CEA researchers (1), show that the Antarctic
Ice Sheet may account for up to 30 cm of sea level rise between 2015 and
2100. However, some scenarios alternatively suggest that the volume added
to the ice sheet by snowfall will surpass what is lost through melting, partially offsetting the rise -- by 7.8 cm at best.

This wide range in estimates (2) mainly reflects incomplete knowledge
of melting that occurs on the bottom of ice shelves. But these floating
glacial fringes, which can cover an area half the size of France, pen
in the rest of the ice sheet. Were they to be lost, the new projections indicate that the ocean would rise several metres over 500 years. Over
the same 2015-2100 period, the Greenland Ice Sheet would contribute
an additional 1.5 to 14 cm, depending on the level of our greenhouse
gas emissions.

These findings have been discussed in a spate of scientific articles,
including five published in The Cryosphere on 17 September 2020.

To refine their predictions, scientists are turning to a new generation
of climate models that directly integrate data on the cryosphere, in
addition to atmospheric, oceanic, and biogeochemical inputs.

Notes: (1) Working at the Institute of Environmental Geosciences (CNRS/Universite' Grenoble Alpes/IRD/Grenoble INP) and Laboratory for
Sciences of Climate and Environment (CNRS/CEA/UVSQ). These labs are
members of the Observatoire des sciences de l'Univers de Grenoble and
Institut Pierre Simon Laplace, respectively.

(2) These estimates are higher than previous ones: the 2019 IPCC Special
Report on the Ocean and Cryosphere in a Changing Climate posited that
melting of the Antarctic Ice Sheet would account for 3 to 28 cm of sea
level rise between 2000 and 2100. However, not only have an insufficient
number of studies been conducted, but those available based their
findings on simpler models of the interactions between ice, the ocean,
and the atmosphere.


========================================================================== Story Source: Materials provided by CNRS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Nicolas C. Jourdain, Xylar Asay-Davis, Tore Hattermann, Fiammetta
Straneo, He'le`ne Seroussi, Christopher M. Little, Sophie Nowicki. A
protocol for calculating basal melt rates in the ISMIP6 Antarctic
ice sheet projections. The Cryosphere, 2020; 14 (9): 3111 DOI:
10.5194/tc-14- 3111-2020 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200917122838.htm

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