A group of scientists says it has now reconstructed the history of the planet’s sea levels arcing back over some 3,000 years — leading it to conclude that the rate of increase experienced in the 20th century was “extremely likely” to have been faster than during nearly the entire period.
An international team of scientists examined two dozen locations across the globe to chart rising and falling seas over centuries and millennia.
Until the 1880s and the world’s industrialization, the fastest seas rose was about 3cm to 4cm a century. During that time global sea levels did not get much higher or lower than 7.6cm above or below the 2,000-year average. But in the 20th century the world’s seas rose 14cm.
Two different studies published on Monday in the journal Proceedings of the National Academy of Sciences said that by 2100 the world’s oceans would rise between 28cm to 131cm, depending on how much heat-trapping gas Earth’s industries and vehicles expel.
Experts say the situation will grow far worse in the 22nd century and beyond, likely requiring the abandonment of many of the world’s coastal cities.
“I think we can definitely be confident that sea-level rise is going to continue to accelerate if there’s further warming, which inevitably there will be,” said Stefan Rahmstorf, a professor of ocean physics at the Potsdam Institute for Climate Impact Research in Germany and co-author of a paper released Monday by the Proceedings of the National Academy of Sciences.
“Ice simply melts faster when the temperatures get higher,” Rahmstorf added. “That’s just basic physics.”
In a report issued to accompany that scientific paper, a climate research and communications organization in Princeton, N.J., Climate Central, used the new findings to calculate that roughly three-quarters of the tidal flood days now occurring in towns along the East Coast would not be happening in the absence of the rise in the sea level caused by human emissions.