The rise in sea level threatens to overwhelm one of the largest cities in antiquity. A drama for humanity.
San Francisco, Miami, Venice, Amsterdam … Number are the cities dedicated to disappear due to global warming if nothing is done. In France alone, around 900 municipalities would be threatened by the rise in sea level. In total, nearly 1.4 million people could live under the high tide line by 2050, from Aquitaine to Hauts-de-France. Coastal cities have only two options: adapt or perish.
Researchers point out that strengthening infrastructure, solutions favored by cities located in rich countries, is necessary, but will not be enough. “The problem of dikes and barriers is that it will undoubtedly always be necessary to strengthen them as the intensification of events progresses, and the infrastructure can also create a false feeling of security while the amplification of the impacts is non-linear. The Japanese knew this during the 2011 tsunami”, deciphers the author of the IEGC François Gemenne to the World.
If the increase in water level is now scientific consensus, the risk of erosion and flood has never been so high. Over the past two decades, the rise in sea level has even led to the collapse of 280 buildings in Alexandria. According to a study published in February in the journal Earth’s Futurethe rhythm to which the buildings collapse along the seafront of this ancient city has gone from once a year to forty times a year.
In the future, 7000 other buildings may collapse due to elevation of sea level and subsequent intrusion of sea water in the foundations of the citydetails The report. Concretely, thehe soil sags, buildings vacillate, and the risk of collapse grows. Worse still, salt water eats away the steel of the foundations, inexorably weakening the structures. Faced with the scale of the phenomenon, thea city of birth of Cleopatra, immense cultural capital of Greek antiquity, may well disappear.
According to the National Oceanic and Atmospheric Administration (NOAA), the average ocean level has increased by around 23 cm since 1880, with significant acceleration in recent decades, reaching 7.5 cm in 25 years. “We are witnessing the gradual disappearance of historic coastal cities. And Alexandria is already sounding the alarm. It is no longer a question of a climate threat but of a reality,” warns Essam Heggy, co-author of the study.