Alarming Surge in Building Collapses in Alexandria Linked to Rising Sea Levels

A recent study from the University of Southern California (USC) has revealed a startling increase in building collapses in the ancient Egyptian port city of Alexandria. What was once a rare occurrence has escalated from approximately one per year to a staggering 40 per year over the past decade. This alarming trend can be directly attributed to rising sea levels and seawater intrusion, according to the research published in Earth’s Future, an AGU journal.

Once known as the “bride of the Mediterranean” for its unmatched beauty and historical significance, Alexandria now stands as a cautionary tale of the consequences of unchecked climate change.

Alexandria’s strategic location on the southern coast of the Mediterranean has made it a focal point for historical and cultural exchange. (Google Map)

Essam Heggy, a water scientist at the USC Viterbi School of Engineering and the study’s corresponding author, said, “The 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.”

Coastal Erosion: Sinking Cities and Rising Seas

Small sea level increases—merely a few centimeters—can have profound impacts, even on cities historically resilient to natural disasters like Alexandria. The city has withstood earthquakes, storm surges, tsunamis, and other calamities over the centuries. However, rising seas and intensified storms, exacerbated by climate change, are rapidly eroding the achievements of millennia of architectural prowess.

Similar concerns are emerging in modern metropolises like Los Angeles, where recurrent flash floods and mudslides complicate recovery from wildfires. The research also aligns with troubling findings from NASA and NOAA, which indicate that parts of California, including the San Francisco Bay Area, Central Valley, and coastal Southern California, are experiencing subsidence. Such minor shifts can significantly elevate flood risks and facilitate saltwater intrusion.

Sara Fouad, a landscape architect at the Technical University of Munich (TUM) and the study’s first author, emphasized, “For centuries, Alexandria’s structures stood as marvels of resilient engineering, enduring earthquakes, storm surges, tsunamis, and more. Now, rising seas and intensifying storms—fueled by climate change—are undoing in decades what took millennia of human ingenuity to create.”

Tracking Coastal Erosion in Alexandria, Egypt

The USC-led study employed a comprehensive method to assess the impact of shoreline changes on Alexandria’s buildings. Researchers created a detailed digital map of collapsed structures in six districts of the city’s historic urban area, documenting key details such as location, size, materials, age, foundation depth, and number of floors. Data were collected from site visits, government reports, news archives, and private construction companies, covering the period from 2001 to 2021.

They also combined satellite imagery with historical maps from 1887, 1959, and 2001 to track shoreline movement and better understand the impact of coastal shifts on groundwater levels. Historical maps revealed that parts of Alexandria’s 50-mile coastline have receded by tens of meters in the past two decades, leading to rising groundwater levels that compromise building foundations.

Chemical analysis of soil samples through isotope fingerprinting also provided insights into the effects of seawater intrusion. The researchers measured B7 isotopes, which indicate soil stability. Lower B7 levels signaled soil erosion, which exacerbates the risk of building collapses.

Ibrahim H. Saleh, a soil radiation scientist at Alexandria University and co-author of the study, commented, “Our isotope analysis revealed that buildings are collapsing from the bottom up, as seawater intrusion erodes foundations and weakens the soil. It isn’t the buildings themselves, but the ground underneath them that’s being affected.”

A Nature-Based Solution to Protect Coastal Cities

To combat coastal erosion and seawater intrusion, the researchers propose a nature-based solution: the creation of sand dunes and vegetation barriers along the coastline. This sustainable and cost-effective approach can help block encroaching seawater, preventing it from raising groundwater levels near building foundations. The strategy benefits not only Alexandria but also other densely urbanized coastal regions around the world.

Steffen Nijhuis, a landscape-based urbanist from Delft University of Technology in the Netherlands and a co-author of the study, highlighted the importance of this approach: “Preserving the diverse architectural attributes of Mediterranean historic cities is a powerful reminder of how landscape transformation has played a crucial role in creating climate-resilient societies.”

Essam Heggy underscored the cultural significance of Alexandria: “Historic cities like Alexandria, which represent the cradle of cultural exchange, innovation, and history, are crucial for safeguarding our shared human heritage. 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.”

Conclusion and Future Outlook

The findings of this study highlight the urgent need for global action to address the escalating threats to coastal cities. Alexandria stands as a poignant example of how even the most resilient urban centers can fall victim to the relentless march of climate change. The proposed nature-based solutions offer a promising pathway to mitigate these risks while preserving cultural heritage.

As we face the reality of rising sea levels and intensified storms, it is imperative that we embrace innovative solutions and prioritize the preservation of our coastal heritage. The future of Alexandria—and countless other historic cities—depends on it.

What are your thoughts on these findings? How can we collectively address the challenges facing Alexandria and other coastal cities? Share your insights in the comments below.

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