Fastest sea-level rise in 2,100 years linked to climate change
By Wendy Koch (USA Today) - June 23, 2011
The sea-level is now rising faster along the U.S. Atlantic coast than at any time in the past 2,100 years, and this surge is linked to increasing global temperatures, an international research team reports.
“Sea-level rise is a potentially disastrous outcome of climate change, as rising temperatures melt land-based ice and warm ocean waters,” said study co-author Benjamin Horton of the University of Pennsylvania. The study was published this week in the Proceedings of the National Academy of Sciences.
The team found that sea level was relatively stable from 200 BC to 1,000 AD. Beginning in the 11th century, sea level rose by about half a millimeter each year for 400 years during a warm climate period known as the Medieval Climate Anomaly. Sea level was stable again during a period, called the Little Ice Age, that persisted until the late 19th century. But since then, sea level has risen more than 2 millimeters per year on average, the steepest rate for more than 2,100 years.
To reconstruct sea level, the scientists used microfossils preserved in sediment cores taken from coastal salt marshes in North Carolina. They estimated the age of the cores using radiocarbon dating and other techniques. They tested their approach by comparing their calculations with tide-gauge measurements from North Carolina for the past 80 years and global ones for the past 300 years. They also confirmed their findings with a second reconstruction from Massachusetts.
The research was done by, in addition to Horton, Andrew Kemp of Yale University, Jeffrey Donnelly of the Woods Hole Oceanographic Institution, Michael Mann of Pennsylvania State University, Martin Vermeer of Aalto University School of Engineering in Finland and Stefan Rahmstorf of Potsdam Institute for Climate Impact Research in Germany.
Funding for the work was provided by the National Science Foundation, the National Oceanic and Atmospheric Administration, United States Geological Survey, the Academy of Finland, the European Science Foundation through European Cooperation in Science and Technology and the University of Pennsylvania.