How High Will Sea Levels Rise?

by |May 29, 2014
Lamont-Doherty graduate student Mike Sandstrom uses a high-accuracy GPS to measure the top elevation of a beach ridge (possibly of Pleistocene age), while others look for fossils just below it. These will help Pliomax scientists understand the relationship between the ridge and past sea level. (Photo: Maureen Raymo)

Lamont-Doherty Earth Observatory graduate student Mike Sandstrom uses a high-accuracy GPS to measure the top elevation of a beach ridge (possibly of Pleistocene age) in Patagonia, while others look for fossils just below it. The data and fossils will help Pliomax scientists understand the relationship between the ridge and past sea level. (Photo: Maureen Raymo)

Scientists from Lamont-Doherty Earth Observatory are trying to determine how high sea levels may rise in the future by studying the shorelines of the past. Their research is part of a five-year project funded by the National Science Foundation called Pliomax. Led by a team of scientists including Lamont-Doherty climate scientist and marine geologist Maureen Raymo, the goal of Pliomax is to increase the accuracy of global sea level estimates for the Pliocene era, which occurred about 3 million years ago.

During the Pliocene, levels of carbon dioxide in the atmosphere varied from between 350 to 450 parts per million (ppm) and Earth’s average temperature was between two and three degrees Celsius warmer than it is today. Levels of atmospheric CO2 are now around 400 ppm, and Earth’s temperature is expected to rise a few degrees during the 21st century due to the increasing amounts of greenhouse gases in the atmosphere. These factors make the climate of the Pliocene similar to that of the near future.

After the Pliocene era, as the planet cooled and sea levels fell, beaches and reefs around the world were left high and dry. During their field expeditions, Pliomax researchers look for evidence of these ancient beaches, measure the height of the beach above current sea level and collect fossil shells from the sites, which are dated in the laboratory to determine the age of the beach. Each of these measurements is used to determine how high sea level was during the Pliocene, information that will help scientists predict how high sea level might rise as the planet grows warmer and atmospheric CO2 continues to increase.

The Pliomax project has a significant global fieldwork component: in the last few years, project scientists have traveled more than 10,000 kilometers on five continents to document past coastlines and sea levels.

The video below, filmed and produced by Lamont postdoctoral researcher and Pliomax scientist Alessio Rovere, describes the team’s research and shows the scientists at work during a recent trip to Patagonia.

To learn more about Pliomax, visit the project website and follow @pliomax on Twitter.

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