Sea-level rise in the 21st century is expected to worsen coastal flooding.(Photo: Arnon Polin)
Sea levels<span style="color: Red;">*</span>rose faster in the past century than during the previous 27 centuries due to<span style="color: Red;">*</span>man-made global warming,<span style="color: Red;">*</span>a pair of studies published Monday found.
"The 20th century rise was extraordinary in the context of the last three millennia — and the rise over the last two decades has been even faster," said Robert Kopp, study lead author and an associate professor at Rutgers University.
The study, "Temperature-driven global sea-level variability in the<span style="color: Red;">*</span>Common Era," was<span style="color: Red;">*</span>published in the peer-reviewed
Proceedings of the National Academy of Sciences.
To reach their conclusions, the scientists compiled a<span style="color: Red;">*</span>database of geological sea-level indicators from marshes, coral atolls and archaeological sites around the world that spanned the last 3,000 years.
Global sea levels stayed<span style="color: Red;">*</span>fairly steady for about 3,000 years. Then, with the<span style="color: Red;">*</span>Industrial Revolution, global sea levels began to rise, the study said.<span style="color: Red;">*</span>Scientists say the seas rose<span style="color: Red;">*</span>5.5 inches from 1900 to 2000, a significant increase, especially for low-lying coastal areas.
The burning of fossil fuels for energy produces heat-trapping greenhouse gases. The warm air<span style="color: Red;">*</span>cause glaciers and ice sheets in Greenland and Antarctica to melt. Warm<span style="color: Red;">*</span>water expands,<span style="color: Red;">*</span>taking<span style="color: Red;">*</span>up more space than cooler water or ice.<span style="color: Red;">*</span>Global sea levels have closely mirrored temperature changes over the years. As temperatures go up, so do sea levels.
Rising sea levels have already impacted U.S. coastal cities.
Parts of Norfolk, Va.,<span style="color: Red;">*</span>Charleston, S.C.,<span style="color: Red;">*</span>and Miami flood at high tides, even when it's not raining,<span style="color: Red;">*</span>according to the National Oceanic and Atmospheric Administration. Floods from storm surges, magnified by the rise in the sea level, have devastated cities including<span style="color: Red;">*</span>New Orleans and New York.
Another study<span style="color: Red;">*</span>—<span style="color: Red;">*</span>also published Monday in the
Proceedings of the National Academy of Sciences<span style="color: Red;">*</span>by<span style="color: Red;">*</span>scientists from Germany, Spain<span style="color: Red;">*</span>and Columbia University<span style="color: Red;">*</span>—<span style="color: Red;">*</span>found that global sea level could<span style="color: Red;">*</span>increase by roughly one to four feet by 2100, depending on how much carbon dioxide, methane and other gases are<span style="color: Red;">*</span>released into the atmosphere in the coming decades.
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