Sea levels are rising faster than they did 50 years ago and “it’s very likely to get worse in the future,” Nerem said.
The changes are not uniform. Some areas showed sea levels rising more than 25 cm (9 inches) and other regions, such as along the U.S. WestCoast, actually falling, according to an analysis of 23 years of satellite data.
Scientists believe ocean currents and natural cycles are temporarily offsetting a sea level rise in the Pacific and the U.S. West Coast could see a significant hike in sea levels in the next 20 years.
“If you’re going to put in major infrastructure like a water treatment plant or a power plant in a coastal zone … we have data you can now use to estimate what the impacts are going to be in the next 100 years,” Wagner said.
Remains of trees in a coastal ghost forest display rising sea levels on Assateague Island in Virginia. Since 1992, sea levels in some parts of the world have risen more than 25 cm (9 inches) and other regions, such as along the U.S. West Coast, actually falling, according to an analysis of 23 years of satellite data. (Kevin Lamarque/Reuters)
“Even today, normal spring high tides cause street flooding in sections of Miami, something that didn’t happen regularly just a few decades ago,” Feilich said.
More than 150 million people, mostly in Asia, live within one metre (3 feet) of sea level, he added.
The biggest uncertainty in forecasting sea level rise is determining how quickly the polar ice sheets will melt in response to warming temperatures.
“Significant changes are taking place today on ice sheets,” said Eric Rignot, a glaciologist at the University of California in Irvine. “It would takecenturies to reverse the trend of ice retreat.”
Scientists said about one-third of the rise in sea levels is due to the expansion of warmer ocean water, one-third to ice loss from the polar ice sheets and the remaining third to melting mountain glaciers.