Virginia’s barrier islands’ normal resilience to sea-level rise is hurt by climate change, VCU researchers find

Virginia's barrier islands. (Public Domain via Wikipedia)

A study from the Coastal Plant Ecology Lab at Virginia Commonwealth University found that a naturally occurring process that has made barrier islands resilient to sea-level rise has been affected by climate change and is making the islands more susceptible to the impact of rising water levels.

Typically, Virginia’s barrier islands off the coast of the Eastern Shore have stayed above sea level with an “overwash” process that deposited sediment onto the islands’ marsh. But, the study found, more woody vegetation is blocking the process from happening. That growth is brought on by climate change.

“In coastal systems, ecology has pretty much been ignored and we are showing that a species which is expanding specifically due to climate warming is fundamentally changing island migration,” said Julie Zinnert, the principal investigator with the Coastal Plant Ecology Lab and assistant professor in VCU’s Department of Biology. “This paper underscores the importance of looking at change across all sub-environments on a barrier island and not just beach shoreline erosion.”

The authors of the study used aerial images from 1984 to 2016 to calculate that the barrier islands have lost about 19 percent elevation. Meanwhile, researchers estimated a 41 percent increase in the woody vegetation that disrupt the normal overwash process.

“Our analysis demonstrates how the interplay between elevation and interior island vegetative cover influences landward migration of the boundary between upland and marsh (a previously underappreciated indicator that an island is migrating), and, thus, the importance of including ecological processes in the island interior into coastal modeling of barrier island migration and sediment movement across the barrier landscape,” the abstract of the study reads.

The complete study will be published in a future issue of the journal of Global Change Biology.