Researcher estimates future sea level rise by looking to the past

PhysOrg: Boston University College of Arts & Sciences Paleoclimatologist Maureen Raymo and colleagues have published findings that should help scientists better estimate the level of sea level rise during a period of high atmospheric carbon dioxide levels 3 million years ago. That geologic era, known as the mid-Pliocene climate optimum, saw much higher global temperatures that may have been caused by elevated levels of carbon dioxide—an analogy for the type of climate we are causing through human addition of greenhouse gases to the atmosphere.

During the mid-Pliocene climate optimum, sea levels were anywhere between 15 and 100 feet higher than at present because water that is now locked up in glaciers as ice circulated freely through the oceans. Raymo and her colleagues published their findings in the current edition of Nature Geoscience in a paper titled “Departures from eustasy in Pliocene sea-level records.” The paper provides an improved model for interpreting geologic evidence of ancient shorelines.

The team’s findings add to the scientific body of knowledge about mid-Pliocene sea levels. By understanding the extent of sea level rise 3 million years ago, scientists like Raymo hope to more accurately predict just how high the seas will rise in the coming decades and centuries due to global warming.

Through their project, titled PLIOMAX (Pliocene maximum sea level project), Raymo and her colleagues have shared data with a larger community of geoscientists involved in studying similar so-called “high stand deposits” around the world. The accumulated data should shed light on the extent to which we can expect the Greenland Ice Sheet, West Antarctic Ice Sheet, and East Antarctic Ice Sheet to melt due to increasing levels of atmospheric carbon dioxide…

Planktic Foraminifera - some examples from Late Pliocene of Baja California - Mexico. Shot by Antonov