A billion people threatened by rising sea levels or “only” half as much? In a new study, published Tuesday, October 12 in the journal Environmental Research Letters (in English), American and German scientists have measured the difference between a world that respects the Paris climate agreement and one that allows global warming to worsen.
A few weeks before the COP26 in Glasgow, a new climate summit, their results underline the urgency and interest of triggering a reduction in our greenhouse gas emissions, which are the engines of this change and the product of our mode of life. “Most emission reduction policies do not reflect this long-term threat, they collectively point us towards widespread and permanent flooding of many developed areas.”, regret the authors of the study.
As a result of global warming, the ice caps of Greenland and Antarctica are melting and the water expands, causing sea level to rise. Our current trajectory is leading us, according to the forecasts of the IPCC (in English), towards an additional meter by 2100. This new study is projected over the following centuries, from 200 to 2,000 years. The biggest differences in sea level “will take centuries to materialize, but they will be determined in the coming decades”, justify the authors.
Different warming scenarios are compared: from +1.5 ° C or +2 ° C, the objectives of the Paris Agreement, to +4 ° C, one of the worst-case scenarios, via 3 ° C, our current trajectory. As a result, if warming were contained at 1.5 ° C, 7.6% of the world’s population (532 million people) would be in areas below sea level, compared to 14% (one billion people) if global mercury climbed 4 ° C. Currently, 5.3% of the world’s population lives in this situation and 12% are at risk if we continue to emit the same amount of greenhouse gases.
The main countries concerned are China, India, Indonesia, Vietnam and Bangladesh. The analysis does not take into account the defense structures (dikes, pumps) that will eventually be built to face this risk. “Even monumental adaptation measures will not eliminate all the risks”, warn however the authors of the study, by evoking the ruptures of dikes or the breakdowns of the pumps.
Aware that these figures do not necessarily speak to the general public, the authors are accompanying it, with the help of the scientific organization Climate Central, with a visual simulation of the different scenarios, called “Let’s illustrate our future” (in English). Several French cities such as Bordeaux, Anglet and Nice are included.