Melting Antarctic ice sheet could cause sea level to rise 5 meters by the end of the millennium

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Simulated mass loss of the Antarctic ice sheet from 1990 to 3000 expressed as contribution at sea level: fourteen experiments for the non-reduction warming pathway (RCP8.5, SSP5-8.5), three experiments for the reduced emissions (RCP2.6, SSP1-2.6), a historical pass (‘hist’) for 1990-2015 and a control pass for a constant climate 1995-2014 (‘ctrl_proj’) under which the ice sheet is essentially stable. The red and blue boxes to the right show the means for RCP8.5 / SSP5-8.5 and RCP2.6 / SSP1-2.6, respectively; whiskers show full ranges. Phase 1 corresponds to the initial period of ISMIP6 until 2100. Phases 2 to 4 are valid for RCP8.5 / SSP5-8.5 and show an accelerated loss of mass (phase 2), the main instability of the cap West Antarctic glacial (phase 3) and a final phase 4 where the mass loss stabilizes. The graphs below represent the differences in ice surface elevation compared to 2015 (in meters; blue means thickening, red / brown means thinning) for the forced simulation by MIROC-ESM-CHEM / RCP8.5. Credit: Christopher Chambers et al. Journal of Glaciology. 22 December 2021

Scientists predict that continued global warming according to current trends could lead to sea level rise of up to five meters by the year 3000 AD.

One of the many effects of global warming is the rise in sea levels due to the melting and retreating of the Earth’s ice caps and glaciers as well as other sources. As sea level rises, large areas of densely populated coastal land could ultimately become uninhabitable without significant coastal modification. Understanding the impact of different pathways of future climate change on sea level changes caused by ice caps and glaciers is therefore essential.

A team of researchers from Hokkaido University, the University of Tokyo and the Japan Agency for Marine and Terrestrial Science and Technology (JAMSTEC) explored the long-term prospect of the Antarctic ice sheet beyond the 21st century under warming conditions, assuming climatic conditions at the end of the 21st century remain constant. Their models and findings have been published in the Glaciology Journal.

The Ice Cap Model Intercomparison Project for Phase 6 of the Coupled Model Intercomparison Project (ISMIP6) was a major international effort that used the latest generation of models to estimate the impact of global warming on the ice caps from Antarctica and Greenland. The aim was to contribute to the recently released Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC). The contribution of the Antarctic ice sheet to sea level rise by 2100 has been estimated to be -7.8 to 30.0 centimeters under constant warming and 0 to 3 centimeters under reduced emissions. greenhouse gases.

The team used the SICOPOLIS (Simulation COde for POLythermal Ice Sheets) ice cap model to extend the ISMIP6 set of fourteen experiments for the constant warming path and three for the reduced emissions path. Until 2100, the configuration was the same as in the original ISMIP6 experiments. For the period beyond 2100, it was assumed that the climatic conditions of the end of the 21st century remain constant – no other climatic trends were applied. The team analyzed the simulation results with respect to the total mass change of the ice sheet, regional changes in West Antarctica, East Antarctica and the Antarctic Peninsula, as well as the various contributors to the mass change. .

Antarctic ice sheet mass loss simulations show that by the year 3000, the relentless warming trajectory produces a sea level equivalent (SLE) of up to 1.5 to 5 , 4 meters, while for the reduced emissions trajectory, the SLE would be only 0.13 to 0.32 meters. The collapse of the West Antarctic ice sheet, made possible by the fact that the West Antarctic ice sheet mainly rests on a bed that is generally well below sea level, is the main reason for degradation due to relentless warming path.

“This study clearly demonstrates that the impact of 21st century climate change on the Antarctic ice sheet extends far beyond the 21st century itself, and the most serious consequences – the contribution of several meters to sea ​​level rise – will probably not be visible until later, ”says Dr Christopher Chambers of the Institute of Low Temperature Sciences at Hokkaido University and lead author of the article. Future work will include basing simulations on more realistic future climate scenarios, as well as using other ice cap models to model the results. “

Reference: “Mass loss of the Antarctic ice sheet up to the an 3000 under a supported late-21st-century climate” by Christopher Chambers, Ralf Greve, Takashi Obase, Fuyuki Saito and Ayako Abe-Ouchi, December 22, 2021, Glaciology Journal.
DOI: 10.1017 / jog.2021.124

This study was funded by the Japanese Society for the Promotion of Science (JSPS) KAKENHI (JP17H06323, JP17H06104) and the Grant-in-Aid for Japan-France Integrated Action Program (SAKURA Program; JPJSBP120213203).

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