Sea level rise is transforming the U.S. coastline across the country, but researchers have noticed that the rate of sea level rise has increased faster in the last decade around the Gulf and Southeastern coasts.
In a new study published in Nature Communications, researchers from Tulane University found rates of sea level rise of about 10 mm (0.4 inches ) per year around Gulf states and the Southeast since 2010.
They compared a combination of field and satellite measurements from 1900 to 2021 and noticed record rates of sea level rise in the last 12 years. Researchers referred to the accelerated rate as “unprecedented in at least 120 years.” A little under half an inch of sea level rise may seem small, but average sea level has risen by about 0.14 inches a year since the early 1990s, according to the Environmental Protection Agency. They also noticed that the acceleration spans from the Gulf of Mexico up to Cape Hatteras in North Carolina. Higher-than-average rates of sea level rise were also recorded in the Caribbean.
The team examined different factors that could have affected ice-mass loss and air pressure in the region. They couldn’t connect those to the sea level rise in the Gulf and Southeast. Because of this, they came to the conclusion that this is a result of human-caused climate change combined with natural variability in the ocean. The last 12 years, the accelerated rates of sea level rise have correlated with the expansion of the Subtropical Gyre that includes the North Atlantic Ocean and the Caribbean, according to the study. Gyres are systems of rotating ocean currents. Ocean warming and changing wind patterns have altered currents in the gyre, according to the study. Warming water expands, which contributes to some of the rapid sea level rise.
It’s not clear if the ocean variability will continue or how. The observed rate of sea level rise has worsened coastal flooding, a trend already set in motion by climate change. “These high rates of sea-level rise have put even more stress on these vulnerable coastlines, particularly in Louisiana and Texas where the land is also sinking rapidly,” Torbjörn Törnqvist, co-author and an environmental science professor at Tulane, said in a statement.
Törnqvist is right. Gulf states like Louisiana are struggling with erosion. According to data from the U.S. Geological Survey, that state lost an estimated 2,000 square miles of land between 1932 and 2016. That’s an area larger than the state of Rhode Island. According to the Texas General Land Office, 64% of the Texas coast is eroding at about 6 feet per year, and the average rate of erosion for that state is about 4 feet per year. Sea level rise has been a known risk for Florida’s coast for a long time, but flooding and king tides are projected to happen more often in the sunshine state in the near future. Increased flooding has also messed with the real estate market, as homeowners in flood zones could see property values plunge.
“Results, once again, demonstrate the urgency of the climate crisis for the Gulf region. We need interdisciplinary and collaborative efforts to sustainably face these challenges,” said Sönke Dangendorf, study author and a Tulane professor.
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