From the air, Hamburg appears safe from sea level rise: the epicenter of German shipping is 110 kilometers from the open sea. Built strategically along the powerful Elbe River, Hamburg is nestled deep within Jutland, a 70,000-square-kilometer peninsula about the size of Ireland that separates the North Sea from the Baltic.
But three times this past January, hurricane-force winds pushed strong storm surges up the channel, overwhelming the downstream flow of one of Europe’s largest rivers. Water rose two meters above the river’s banks. It wasn’t as bad as the 1962 flood that swamped 120 square kilometers and destroyed 6,000 homes, but it was a reminder that those living in Hamburg—along with the five million people living in other coastal European cities—face a growing threat of extreme floods fueled by global warming.
Hamburg is accustomed to flooding. When this year’s floods rolled up the Elbe, people were ushered away from the historical fish market, and the trawlers in the harbor were evacuated. The sea was allowed to sweep across the waterfront, spilling through the 300-year-old great market hall.
It was not a big deal. “All we have to do is clean up afterward,” says Olaf Müller, chief of the city agency for roads, bridges, and waters. “We live with the water there. When the floods come, we open the doors.”
But by the end of the century, extreme floods that once happened only every 100 years will occur annually along Europe’s northern coasts, costing cities up to US $40-billion each year. Defensive structures will crumble under intensifying waves.
“It’s an eye-opener—I can’t even begin to comprehend it,” says Michalis Vousdoukas, whose new report for the Europe Joint Research Centre analyzes the risk of extreme flooding across Europe. But there’s still a major disconnect between projections of future sea level rise and current flood protection infrastructure, he says: most existing barriers are engineered for today’s climate. “They will be obsolete in the decades ahead.”