An international team of environmental scientists led by the University of Pennsylvania has shown that sea-level rise along the Atlantic Coast of the United States was two millimeters faster in the 20th century than at any time in the past 4,000 years.
Researchers corrected relative sea-level data from tide gauges using the coastal-subsidence values.
Results clearly show furthermore that the magnitude of the sea-level rise increases in a southerly direction from Maine to South Carolina.
This is the first demonstrated evidence of this phenomenon from observational data alone.
Researchers believe this may be related to the melting of the Greenland Ice Sheet and ocean thermal expansion.
“There is universal agreement that sea level will rise as a result of global warming but by how much, when and where it will have the most effect is unclear,” said Benjamin P. Horton, assistant professor in the Department of Earth and Environmental Science at Penn.
“Such information is vital to governments, commerce and the general public. An essential prerequisite for accurate prediction is understanding how sea level has responded to past climate changes and how these were influenced by geological events such as land movements,” he added.
The study provides the first accurate dataset for sea-level rise for the U.S. Atlantic coast, identifying regional differences that arise from variations in subsidence and demonstrate the possible effects of ice-sheet melting and thermal expansion for sea level rise.
The results appear in the December 1 issue of the journal Geology.