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Nature

2°C Global warming: Sea level could rise by 2.5 metres

melting Iceberg

The sea level will rise by 2.5 meters even if the 2015 Paris Climate Agreement goals are met. The equivalent sea-level rise to the Antarctic Ice Sheet loss could reach 1.3 meters per degree of warming up to 2 degrees above pre-industrial levels. Coastal regions are at high risk. Are we ready to give up the Mauritian coastline? 

Antarctica is committed to becoming virtually ice-free, according to a paper published in the journal Nature. A phenomenon to be taking place over a long period, beyond this century. This would most certainly be irreversible. 

Antarctica hysteresis reveals high risks of sea-level rise

The ice sheet will cause a rise of 1.3 meters of sea-level per degree of warming up to 2 degrees above pre-industrial levels. This could almost double to 2.4 metres per degree of warming if the temperature rises between 2 and 6 degrees. Even worse, the sea level could increase to about 10 metres per degree of warming between 6 and 9 degrees. 

More than half of Earth’s freshwater resources are held by the Antarctic Ice Sheet, representing by far the largest potential source for global sea-level rise under future warming conditions. And, its long-term stability determines the fate of our coastal cities and cultural heritage.

Antarctic ice velocities and surrounding ocean temperatures-copyright Nature
copyright @Nature

According to the study, each of these thresholds gives rise to hysteresis behaviour. The currently observed ice-sheet configuration is not regained even if temperatures are reversed to present-day levels. 

The West Antarctic Ice Sheet would not regrow to its modern extent unless temperatures are at least one degree Celsius lower than pre-industrial levels. If the Paris Agreement is not met, Antarctica’s long-term sea-level contribution will dramatically increase and exceed all other sources.

The fate of coastal regions in our hands

The Antarctic Ice Sheet comprises an ice mass equivalent to 58m of global sea-level rise. Therefore, its future evolution and the associated sea-level change are of profound importance to coastal populations, ecosystems, and economies. 

“The Antarctic ice sheet has existed in roughly its current form for about 34m years, but its future form will be decided in our lifetimes”, says Anders Levermann, co-author of the article and researcher at Potsdam Institute for Climate Impact Research, Potsdam University.

Anders Levermann explains: “We decide now whether we manage to halt the warming. So Antarctica’s fate lies in our hands – and with it that of our cities and cultural sites across the globe, from Rio de Janeiro’s Copacabana to Sydney’s Opera House. Thus, this study is another exclamation mark behind the importance of the Paris Climate Agreement: Keep global warming below two degrees.” 

As the researchers explain, the warmer it gets, the faster Antarctica loses ice. And much of it will then be gone forever. Consequences for the world’s coastal cities and cultural heritage sites would be detrimental, from London to Mumbai, and from New York to Shanghai. And Anders Levermann adds: “If we give up the Paris Agreement, we give up Hamburg, Tokyo and New York.” 

And what about the fate of small islands developing states (SIDS) like Mauritius? Are we going hysterical over this complex physical phenomenon of hysteresis?

As said in a previous article, several coastal regions in Mauritius are concerned. The capital, Port-Louis, the Tombeau Bay region, and the south-east coast, seem to be the most to be affected according to the interactive map of the Climate Central project.