With global warming, sea levels are set to rise. A phenomenon which, depending on the scale it takes, will more or less severely affect populations and economies.
Osaka, Calcutta, The Hague, Shanghai. What these cities have in common is that they are threatened by rising sea levels due to global warming. Because we now unfortunately know that a global increase in temperatures leads to a rise in water levels. Because global warming causes melting ice cream, but also dilation thermals of the oceans. In the state liquidhot water takes up “more space” than cold water.
The average overall elevation of the sea level is of course depending on the scenarios ofemissions of greenhouse gases. Measurements – made using tide gauges, but also satellites – show that the level has already risen by some 20 centimeters since 1900. And until recently, researchers did not imagine that the rise could exceed 60 centimeters by 2100. But over the course of studies and new data, opinions have changed. Sea level rise accelerated from +1.4 mm/year between 1930 and 1992 to +3.3 mm/year between 1993 and 2009.
Sea level: variable estimates
If we cannot stop the crazy growth of greenhouse gas emissions, the Intergovernmental Panel on Climate Change (IPCC) warned, in a report released in September 2019, that the sea level would rise by more than 1.10 meters. And the most pessimistic global warming scenarios even mention the possibility of exceeding 2 meters. For the National Oceanic and Atmospheric Administration (NOAA – United States), the rise will reach 2.5 meters in 2100. The Central Climate Institute, for its part, imagines a rise of 2.9 meters with an increase in temperatures not exceeding 1.5°C.
Changes in the dynamics of the ice caps could even have even more dramatic consequences. In recent decades, the ice has melted faster than expected. Thus between 1992 and 2001, the loss of ice in Greenland only contributed to sea level rise by 0.09 mm/year. But over the following ten years, its contribution increased to 0.59 mm/year. The trajectory is the same for Antarctica. And we know that if all of Greenland and Antarctica were to melt, the sea level rise would be several tens of meters.
Note, however, that some studies are more measured. Whereas the melting ice may be more limited than imagined in the years to come, they do not predict more than 90 centimeters of global sea level rise by 2100.
Click here to simulate on a map the floods caused by sea level rise.
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