Wednesday, May 29, 2019

Study explores risk of rising sea levels to rural coastal areas

A "ghost forest," trees killed by saltwater intrusion (Photo from Virginia Institute of Marine Science)
A new study highlights the probable impact of rising sea levels on rural coastal areas. "The paper—based on research funded by the National Science Foundation—is the first effort to synthesize the growing number of studies of land conversion driven by sea-level rise. One of the clearest signs of this conversion are 'ghost forests'—stands of dead trees with new marshlands lapping at their bleached trunks," David Malmquist reports for

Ghost forests are one of the most noticeable signs of climate change, according to lead author Matt Kirwan, an associate professor at The College of William & Mary's Virginia Institute of Marine Science. Moreover, he writes, "Recent research shows that submergence of rural land—marked by ghost forests and abandoned farm fields—is widespread, ecologically and economically important, and globally relevant to the survival of coastal wetlands."

All over the world, forests are turning into ghost forests more quickly than they once did. In the mid-Atlantic, it's happening more than twice as fast as even 150 years ago. More than 150 square miles of forest have turned into marshland since the mid-1800s, the study notes.

"Kirwan and his co-author, Keryn Gedan of George Washington University, note that the scientific community's emerging recognition of this issue has generated widespread interest in better understanding the many factors that influence the extent and pace of upland-to-wetland conversion," Malmquist reports. "These include the rate of sea-level rise, slope of the upland, tidal range, amount of sediment available for vertical marsh growth, salt tolerance of different tree and grass species, and—critically—the presence of levees and other human barriers both large and small."

Flood-defense strategies could help protect forests from rising sea levels, the authors write. They recommend that researchers study the effectiveness of local and privately owned barriers and the probability and consequences of their failure, to help landowners, government officials and environmental groups decide how best to protect the land or whether it wouldn't be feasible to save it. They also recommend studying whether stopgap solutions, like planting salt-tolerant crops and harvesting susceptible timber, will help private landowners preserve some of the value of their land.

Finally, the researchers recommend lawmakers study how policy incentives could influence future transitions from upland to wetland. "They suggest that offerings such as U.S. Department of Agriculture's Conservation Reserve Program, in which farmers are paid to remove environmentally sensitive land from production, could be re-purposed as instruments for adapting to sea-level rise. They also recommend that policymakers use regional predictions of wetland gain or loss to set incentives for prioritizing wetland migration or upland protection," Malmquist reports.

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