Even if humanity beats the odds and caps global warming at 1.5 degrees Celsius above pre-industrial levels, seas will rise for centuries to come and swamp cities currently home to half-a-billion people, researchers warned Tuesday.
In a world that heats up another half-degree above that benchmark, an additional 200 million of today’s urban dwellers would regularly find themselves knee-deep in sea water and more vulnerable to devastating storm surges, they reported in Environmental Research Letters.
Worst hit in any scenario will be Asia, which accounts for nine of the 10 mega-cities at highest risk.
Land home to more than half the populations of Bangladesh and Vietnam fall below the long-term high tide line, in a world with even a 2 degrees Celsius rise. Built-up areas in China, India and Indonesia would also face devastation.
Most projections for sea level rise run to the end of the century. But oceans will continue to swell for hundreds of years beyond 2100 — fed by melting ice sheets, heat trapped in the ocean and the dynamics of warming water — no matter how aggressively greenhouse gas emissions are drawn down.
