An international team of scientists has determined that the Atlantic Ocean rose faster in the 20th century than at any time in the last 4,000 years, but not uniformly along the coast.
One of the researchers, assistant professor Benjamin Horton in the Department of Earth and Environmental Science at the University of Pennsylvania, says: “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.” He and other researchers have now started to tackle this issue.

Interestingly, the rate of sea level rise in recent years varies according to how far north or south you are on the coast.The researchers’ findings show a sea level rise 2 millimeters higher than the background rate of the last 4,000 years. They also show that it was greater the further south you went, from Maine to South Carolina, on the Atlantic coast of the United States. This is, apparently, the first “demonstrated evidence of this phenomenon from observational data alone.”

Horton says knowing more about past sea level rise is important to usefully tracking and predicting where and when sea level will rise as a result of rapid human-induced climate change. “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.”

Horton and the others identified that previously (in the past 4,000 years) sea level rise was primarily due to coastal subsidence, which is land being “lost to subsidence as the earth continues to rise in response to the removal of the huge weight of ice sheets during the last glacial period.” The researchers believe that this increased rate of sea level rise in the last 100 years or so is related to the melting of the Greenland Ice Sheet combined with ocean thermal expansion.

Source - GO Media - Written by Zachary Shahan - Image Credit: Paulo Brandão via flickr under a Creative Commons license