Study: Our coast is sinking & sea levels are rising prompting calls for action

Study: Our coast is sinking & sea levels are rising prompting calls for action

North Carolina’s coastal plain is sinking between one to three millimeters each year

GREENVILLE, N.C. (WITN) – We’ve seen the videos of the Atlantic claiming houses off the Outer Banks. Many point to rising sea levels being the main culprit, and rightly so as oceans have risen 3.6 inches (9.1cm) since 1993. But there’s another issue that has gone unnoticed to most. A recent study out of Virginia Tech is highlighting the subsidence, or sinking, of coastal cities in the U.S.

A recent study out of Virginia Tech highlights the rate of subsidence (sinking) along the Atlantic, Gulf and Pacific coasts.

A recent study out of Virginia Tech highlights the rate of subsidence (sinking) along the Atlantic, Gulf and Pacific coasts.

The research team was lead by Leonard Ohenhen, a graduate student working with Associate Professor Manoochehr Shirzaei at Virginia Tech’s Earth Observation and Innovation Lab. Ohenhen and Shirzaei used satellite obtained measurements to determine precise elevation readings for 32 cities along the Atlantic, Pacific and Gulf coasts. They found that the highest level of subsidence (sinking) is occurring along the Gulf Coast with relatively rapid subsidence along the coast of Louisiana. According to the study, the coastal plains of North Carolina are experiencing 1-3 mm of subsidence each year.

Adding in the increased propensity for coastal flooding due to sea level rise caused by climate change, the team was able to show potential flooding dangers that are expected to occur by 2050 (within the next 26 years). They estimate that 500 to 700 square miles of land will flood, directly impacting 178,000 to 518,000 people and costing between $32 billion to $109 billion.

We are on the frontlines of this issue as houses have been claimed by the sea up and down the North Carolina coast. This past Sunday, Highway 12 on Ocracoke was shut down due to ocean over wash caused by windy weather. Relatively mild storms are now leading to much more impactful consequences than what was felt 30 years ago. Even elevated tidal events like King Tides are creating flooding hazards from Virginia Beach to Myrtle Beach and every where in between that touches the water.

Ohenhen superbly highlighted the issue with an analogy “Imagine you are in that boat with a steady leak, slowly causing the boat to sink. That leak symbolizes sea-level rise or broadly flooding. What would happen if it also starts raining? Even a minor rainfall or drizzle would cause the boat to sink more quickly than you thought it would. That’s what land subsidence does — even imperceptible millimeter land subsidence exacerbates existing coastal hazards.”

The purpose of the study was not to just raise alarm bells for those living along the coast, but to help enact better city planning and flood resiliency decisions in those threatened communities. Robert Nicholls, a professor of climate adaptation at the University of East Anglia in the U.K., also participated in the research and said “This study demonstrates that we can now measure vertical land motion at a sufficient scale to create a useful climate service that supports planning and management decisions on flooding.” For more information on this study from Virginia Tech, you can go here.

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