Last year, a building collapsed in the Wardiyan neighborhood of Alexandria, killing four people. This incident is emblematic of a growing crisis facing Egypt's historic port city: the alarming rate at which its buildings are collapsing due to rising sea levels and coastal erosion.
Over the past two decades, more than 280 buildings have collapsed in Alexandria, resulting in the deaths of 85 people and raising concerns among experts and local authorities. The frequency of these collapses has surged from approximately one per year to about 40 per year over the past decade, leaving locals helpless as they witness the deterioration of their city, according to The Hill.
Researchers from the University of Southern California and Alexandria University conducted a study analyzing satellite images from 2001 to 2021 alongside historical maps from 1887 and 1959. Their findings indicate that Alexandria has lost tens of meters of coastline over the past twenty years and has moved inland by dozens of meters in recent decades.
The primary causes of this destruction are rising sea levels and the intrusion of saltwater into the soil, which penetrates beneath houses and erodes the foundations of seaside structures, increasing the risk of collapse. This phenomenon is leading to soil erosion, land subsidence, and corrosion of the steel reinforcement in building foundations, contributing to the collapse of buildings from the bottom up.
According to the National Oceanic and Atmospheric Administration (NOAA), since 1880, the global sea level has risen by 20–23 centimeters, and even a small rise of just a few centimeters can have enormous consequences. In some areas of Alexandria, soil erosion reaches 24–36 meters per year.
"The true cost of this loss extends far beyond bricks and mortar. We are witnessing the gradual disappearance of historic coastal cities, with Alexandria sounding the alarm. What once seemed like distant climate risks are now a present reality," said Essam Heggy, a water scientist at the USC Viterbi School of Engineering and the study's corresponding author.
"Our study challenges the common misconception that we only need to worry when the sea level rises by a meter. What we are showing here is that coastlines around the world are already changing and causing building collapses at a pace we have never seen before," Heggy added, as reported by The Hill.
The city of Alexandria, founded around 330 BCE by Alexander the Great, is considered a cradle of civilization and is one of the most vulnerable cities to rising sea levels, which threaten its historical heritage and risk causing it to disappear from the map. The city's structures have stood as marvels of engineering for centuries, enduring earthquakes, storm surges, tsunamis, and more.
"But now, rising seas and intensifying storms—fueled by climate change—are undoing in decades what took millennia of human ingenuity to create," said Sara Fouad, a landscape architect at the Technical University of Munich and the study's first author.
To address this threat, the researchers have proposed the implementation of nature-based solutions. "The creation of sand dunes and vegetative barriers could mitigate the penetration of saline water in Alexandria and help protect the city in the long term," reported El Confidencial.
"This sustainable and affordable approach is applicable in many densely populated coastal areas worldwide," noted Steffen Nijhuis, a landscape urbanist at Delft University of Technology and co-author of the study.
Coastal cities around the world, including those in California, are facing similar challenges due to saltwater intrusion, which weakens infrastructure, degrades water supplies, and drives up the cost of living.
"As climate change raises the sea level and accelerates coastal erosion, protecting these cities is not just about saving buildings, but about preserving our identity," emphasized Heggy.
The study on Alexandria's building collapses was published in the scientific journal Earth's Future.
The article was written with the assistance of a news analysis system.