09-03-2025
Ancient city crumbles as looming threat begins to wreak havoc: 'Undoing in decades what took millennia of human ingenuity to create'
The ancient Egyptian city of Alexandria is increasingly succumbing to rising sea levels and saltwater intrusion. As a result, researchers fear crucial historical information could be lost, and the impacts could be far-reaching.
A team from the University of Southern California examined shoreline changes in Alexandria using a three-pronged approach, according to a news release published by EurekAlert.
Using satellite imagery and historical maps from 1887, 1959, and 2001, the researchers created a detailed digital map of Alexandria's densely populated urban area. They also took samples to analyze whether the soil contained low levels of isotopes, which would indicate erosion.
Alexandria soil radiation scientist Ibrahim H. Saleh, one of the study's co-authors, said that "buildings are collapsing from the bottom up, as seawater intrusion erodes foundations and weakens the soil."
"For centuries, Alexandria's structures stood as marvels of resilient engineering, enduring earthquakes, storm surges, tsunamis, and more," added first author Sara Fouad, a landscape architect at the Technical University of Munich. "But now, rising seas and intensifying storms … are undoing in decades what took millennia of human ingenuity to create."
Alexandria is among a growing number of coastal cities in peril. For instance, in Papua New Guinea, rising sea levels have displaced tens of thousands of people. As the researchers pointed out in EurekAlert, rising seas are impacting cities in California, where saltwater intrusion has degraded water supplies, contributed to a higher cost of living, and weakened infrastructure.
"Our study demonstrates that coastal buildings are at risk of collapsing even without directly encroaching on the seawater as widely believed," said corresponding author Essam Heggy, a water scientist at the USC Viterbi School of Engineering.
Situated on the Mediterranean, Alexandria was also a hub of learning, science, and cultural exchange. If things continue on the same trajectory, the knowledge it holds could be diminished or lost because of the effects of rising global temperatures, driven higher at an unnatural rate by human activities, particularly the burning of dirty fuels.
"Historic cities like Alexandria, which represent the cradle of cultural exchange, innovation, and history, are crucial for safeguarding our shared human heritage," Heggy said in the news release. "As climate change accelerates sea level rise and coastal erosion, protecting them isn't just about saving buildings; it's about preserving who we are."
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The USC team is advocating for nature-based solutions to mitigate the situation in Alexandria, per the release. Potential actions include building sand dunes and cultivating vegetation barriers — techniques already proven to boost climate resilience in coastal communities.
Furthermore, as explained by study co-author Steffen Nijhuis, a landscape-based urbanist from the Netherlands' Delft University of Technology, this approach is cost-effective.
In the long term, bringing the planet's temperatures into balance can help slow down the melting of ice sheets — a key factor contributing to rising sea levels and subsequent saltwater intrusion.
As countries around the world increase their mix of nonpolluting, renewable energy, you can support these efforts by upgrading to energy-efficient appliances and unplugging electronic devices when they aren't in use.
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