Alexandria, Egypt, has stood for almost 2400 years. Today, though, parts of it are crumbling—one building at a time. As Earth’s climate changes, the Mediterranean Sea is rising, the coast is eroding, and saltwater is seeping into groundwater supplies. That weakens buildings, causing them to collapse. And according to a recent study, without action to protect the coastline, the problem will get worse in the years ahead.

Alexandria is the largest city on the Mediterranean, and one of the busiest ports. But its maritime location is causing trouble. Researchers looked at records of building collapses over the past quarter century. They also compared the coastline to that of previous decades, studied the soil, and made other observations.

They found that 280 buildings have collapsed in the past 20 years. Over that span, the rate of collapse jumped from fewer than one per year to almost 40. Almost all of the destroyed buildings were within a mile of the coast.

The jump was largely the result of climate change. Higher sea level and stronger storms have eroded the coastline by an average of 12 feet per year, with one district averaging 120 feet. And seawater is filtering into aquifers below the city. That corrodes foundations, causing buildings to crumble.

The scientists recommended creating dunes and greenbelts along the coast to keep the Mediterranean at bay—and keep Alexandria from crumbling into the sea.