Professor examines sea level changes through salt marshes

 

Researchers at the University of Rhode Island are currently involved in several ongoing projects where they use salt marshes to further their understanding of the relationship between sea level change and climate change.

A salt marsh is an area of coastal grassland that is often subject to flooding from the nearby saltwater. They are also habitat to plants and animals that can help researchers to collect an accurate timeline for sea level change. In Rhode Island there is no recorded knowledge of sea level change prior to the 1930s, and any changes recorded are reliant on geological reconstruction from Connecticut and Cape Cod, a small, coastal region of Massachusetts. This lack of data makes the salt marsh projects pivotal for understanding how the sea level has risen prior to human contribution to pollution—a critical tool for coastal management, according to Simon Engelhart, assistant professor of geosciences at URI.

Engelhart said that he has been working with a team composed of two graduate students and some undergraduates within the geosciences major. He and and his team have been working at salt marshes in Rhode Island, including Fox Hill, Galilee and Matunuck State Beach, in order to collect sediment cores and determine the persistency of each salt marsh through geological time.

Sediment cores provide researchers with a better understanding of sea level acceleration in response to climate change through the fossilized plants and animals within the sediment, most commonly Foraminifera or Forams, according to Engelhart. Forams are single-celled algae that are inherently linked to tidal levels.

Due to the fact that some species show preference for spending more time under saltwater while others demonstrate a preference for less time spent in the water, it can be inferred, by which species are evident in the sediment, where the sea level was at that specific time.  By knowing about the historic levels, researchers can observe how sea levels are responding to the changing climate and estimate models for how sea level rise can affect our environment, according to Engelhart.

“With an idea of how the coast line responded in the past, what rates are necessary for coastal rollbacks and how the sea level responded to past periods of warming, we are capable of reproducing models of the oscillations to predict future estimates of sea level rise,” Engelhart said. “The estimates in modeling vary, but Rhode Island is planning for a five-foot rise in sea level by 2100. And while it is unlikely to exceed that, nothing is outside the realm of possibilities.”

He added that “knowing how the sea level has historically responded to climate change” can teach us how to prepare coastlines for future “storm surges.”

In addition to better understanding our past in order to prepare for the future, the salt marsh projects are important to preserving our natural landscapes. One problem that threatens salt marshes is that there is not enough sediment, according to Engelhart. Through sediment cores and models of historic sea level rise, Engelhart and his team are able to observe which marshes are the most resilient or persistent over time so that any funding toward restoration can go toward the marshes that have demonstrated a stability over time.

“Unfortunately, there is not enough money to save every salt marsh, so we have to save the ones we think have the best chances for survival,” Engelhart said.

Engelhart and his team of researchers will continue to dedicate their studies to saving an environment, as well as creating models that illustrate future patterns of sea level rise in relation to climate change.

 

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