Global sea levels could rise by over 6 feet by 2100––twice as much as had previously been predicted––threatening major cities and potentially flooding hundreds of millions of people, a study published Monday warned.
The implications for coastal populations around the world could be severe if the predictions in the study in the Proceedings of the National Academy of Sciences prove accurate. In the worst-case scenario, where global emissions are not curtailed and the climate warms by 5°C (9° Fahrenheit), the report authors predict sea levels could rise by as much as 7.8 feet (2 meters).
Large parts of low-lying countries like Bangladesh would become uninhabitable, while critical areas for food production would be lost. Major cities, including New York and London, would also be threatened, according to the study.
Shanghai, Mumbai and some island nations could become permanently flooded, according to that scenario. Almost 1.8 million square kilometers (about 700,000 square miles) of land, including some used for farming, could be permanently flooded.
“There are roughly 240 million people in the world who would be flooded if we had 7.8 feet of sea level rise,” says Bob Kopp, a climate and sea level scientist with Rutgers University in New Jersey and a co-author of the study. “Most of them are in Asia.”
But it “would also have fairly significant implications for coastal cities in the U.S. like New Orleans and Miami where a large chunk of economic activity is exposed to flooding, as well as other cities like New York and Boston.”
Reports of the rate of glacier melt in Greenland and Antarctica is accelerating at a faster than expected rate. The world is facing a risk of sea level rise “substantially higher than were in the 2013 assessment report of the IPCC,” Kopp says.