Scientists have documented an abnormal and dramatic surge in sea levels along the U.S. gulf and southeastern coastlines since about 2010, raising new questions about whether New Orleans, Miami, Houston and other coastal communities might be even more at risk from rising seas than once predicted.
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The acceleration, while relatively short-lived so far, could have far-reaching consequences in an area of the United States that has seen massive development as the wetlands, mangroves and shorelines that once protected it are shrinking. An already vulnerable landscape that is home to millions of people is growing more vulnerable, more quickly, potentially putting a large swath of America at greater risk from severe storms and flooding.
The increase has already had major effects, researchers found. One study suggests that recent devastating hurricanes, including Michael in 2018 and Ian last year, were made considerably worse by a faster-rising ocean. Federal tide gauge data from the National Oceanic and Atmospheric Administration suggest that the sea level, as measured by tide gauge at Lake Pontchartrain in New Orleans, is eight inches higher than it was in 2006, just after Hurricane Katrina.
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“The entire Southeast coast and the Gulf Coast is feeling the impact of the sea level rise acceleration,” said Jianjun Yin, a climate scientist at the University of Arizona and the author of one of two academic studies published in recent weeks that describe the changes.
Louisiana could be ‘canary in the coal mine’ for rising seas
1:48
Louisiana could be ‘canary in the coal mine’ for rising seas (Video: Zoeann Murphy/The Washington Post)
Yin’s study, published in the Journal of Climate, calculates the rate of sea level rise since 2010 at over 10 millimeters — or one centimeter — per year in the region, or nearly 5 inches in total through 2022. That is more than double the global average rate of about 4.5 millimeters per year since 2010, based on satellite observations of sea level from experts at the University of Colorado at Boulder.
While the annual totals might sound minor, even small changes in sea levels over time can have destructive consequences. Yin’s study suggested that Hurricanes Michael and Ian, two of the strongest storms ever to hit the United States, were made considerably worse in part from additional sea level rise.
“It turns out that the water level associated with Hurricane Ian was the highest on record due to the combined effect of sea level rise and storm surge,” Yin said.
A man stands in front of storm surges in Myrtle Beach, S.C., on Sept. 30, 2022. (Melissa Sue Gerrits for The Washington Post)
Storm surge from Hurricane Ian washed this truck into a swimming pool in Fort Myers Beach, Fla., in September. (Ted Richardson for The Washington Post)
A second study by a long list of sea level experts, led by Sönke Dangendorf of Tulane University and published in Nature Communications, finds the same trend since 2010 across the U.S. Gulf Coast and southeastern coastlines, calling the rise “unprecedented in at least 120 years.”
“It’s a window into the future,” said Dangendorf, who collaborated with experts at multiple U.S. institutions and Britain’s National Oceanography Center. The rates are so high in recent years, Dangendorf said, that they’re similar to what would be expected at the end of the century in a very high greenhouse gas emissions scenario.
An additional two studies on rapid sea level rise and how it is affecting the region have been released by scientists in preprint form but have not yet passed through peer review, suggesting a swell of scientific attention on the subject.
The new findings are striking in part because the rapid rise appears to be caused by profound changes in the ocean. In parts of Texas and Louisiana, sinking land has long been a factor that contributes to sea levels growing relatively higher over time. But in the latest studies, scientists show a rapid rise of sea levels in places such as Pensacola and Cedar Key, Fla., where the land is not sinking as rapidly as it is in places such as Grand Isle, La., or Galveston, Tex.
In general, higher seas in the Gulf of Mexico and around Florida mean that hurricane risks in some of the most exposed and storm-prone parts of the United States are growing only more acute.
In addition, as seas rise and people continue to move to high-risk areas along the coasts, scientists say that millions of acres of U.S. land and hundreds of thousands of homes and offices could slip below swelling tide lines. Experts from the nonprofit First Street Foundation also projected recently that properties in many coastal areas could lose value as flooding intensifies, a shift that could harm homeowners and erode local tax bases.
Scientists are not entirely on the same page about the causes driving the phenomenon, or whether the recent acceleration in rising seas will continue at such a rapid clip. Researchers typically prefer to rely on decades of data to be more certain of trends in the climate system, and their causes. In that context, the recent sea level rise has happened over a relatively short time period. That makes the trend as ambiguous as it is worrying.
Still, this much seems clear: The rapid sea level rise appears to start in the Gulf of Mexico, which has been warming far faster than the global ocean. Warm water naturally expands, causing sea levels to rise. That warm water also gets carried by currents out of the gulf and along the East Coast, affecting places such as Georgia and the Carolinas.
Will this trend continue? That remains less clear, scientists say.
The waters that have helped drive up sea levels in Gulf of Mexico are very warm even at deep levels, based on a preprint study by Jacob Steinberg and colleagues at the Woods Hole Oceanographic Institution, NASA’s Jet Propulsion Laboratory, the University of Hawaii at Manoa and the National Center for Atmospheric Research.
Steinberg and colleagues suggest that the trend implicates a warm current called the Loop Current, which enters the gulf from the Caribbean Sea and in turn is part of a broader pattern of circulation in the Atlantic Ocean.
Want to know how your actions can help make a difference for our planet? Sign up for the Climate Coach newsletter, in your inbox every Tuesday and Thursday.
The acceleration, while relatively short-lived so far, could have far-reaching consequences in an area of the United States that has seen massive development as the wetlands, mangroves and shorelines that once protected it are shrinking. An already vulnerable landscape that is home to millions of people is growing more vulnerable, more quickly, potentially putting a large swath of America at greater risk from severe storms and flooding.
The increase has already had major effects, researchers found. One study suggests that recent devastating hurricanes, including Michael in 2018 and Ian last year, were made considerably worse by a faster-rising ocean. Federal tide gauge data from the National Oceanic and Atmospheric Administration suggest that the sea level, as measured by tide gauge at Lake Pontchartrain in New Orleans, is eight inches higher than it was in 2006, just after Hurricane Katrina.
ADVERTISING
“The entire Southeast coast and the Gulf Coast is feeling the impact of the sea level rise acceleration,” said Jianjun Yin, a climate scientist at the University of Arizona and the author of one of two academic studies published in recent weeks that describe the changes.
Louisiana could be ‘canary in the coal mine’ for rising seas
1:48
Louisiana could be ‘canary in the coal mine’ for rising seas (Video: Zoeann Murphy/The Washington Post)
Yin’s study, published in the Journal of Climate, calculates the rate of sea level rise since 2010 at over 10 millimeters — or one centimeter — per year in the region, or nearly 5 inches in total through 2022. That is more than double the global average rate of about 4.5 millimeters per year since 2010, based on satellite observations of sea level from experts at the University of Colorado at Boulder.
While the annual totals might sound minor, even small changes in sea levels over time can have destructive consequences. Yin’s study suggested that Hurricanes Michael and Ian, two of the strongest storms ever to hit the United States, were made considerably worse in part from additional sea level rise.
“It turns out that the water level associated with Hurricane Ian was the highest on record due to the combined effect of sea level rise and storm surge,” Yin said.
A man stands in front of storm surges in Myrtle Beach, S.C., on Sept. 30, 2022. (Melissa Sue Gerrits for The Washington Post)
Storm surge from Hurricane Ian washed this truck into a swimming pool in Fort Myers Beach, Fla., in September. (Ted Richardson for The Washington Post)
A second study by a long list of sea level experts, led by Sönke Dangendorf of Tulane University and published in Nature Communications, finds the same trend since 2010 across the U.S. Gulf Coast and southeastern coastlines, calling the rise “unprecedented in at least 120 years.”
“It’s a window into the future,” said Dangendorf, who collaborated with experts at multiple U.S. institutions and Britain’s National Oceanography Center. The rates are so high in recent years, Dangendorf said, that they’re similar to what would be expected at the end of the century in a very high greenhouse gas emissions scenario.
An additional two studies on rapid sea level rise and how it is affecting the region have been released by scientists in preprint form but have not yet passed through peer review, suggesting a swell of scientific attention on the subject.
The new findings are striking in part because the rapid rise appears to be caused by profound changes in the ocean. In parts of Texas and Louisiana, sinking land has long been a factor that contributes to sea levels growing relatively higher over time. But in the latest studies, scientists show a rapid rise of sea levels in places such as Pensacola and Cedar Key, Fla., where the land is not sinking as rapidly as it is in places such as Grand Isle, La., or Galveston, Tex.
In general, higher seas in the Gulf of Mexico and around Florida mean that hurricane risks in some of the most exposed and storm-prone parts of the United States are growing only more acute.
In addition, as seas rise and people continue to move to high-risk areas along the coasts, scientists say that millions of acres of U.S. land and hundreds of thousands of homes and offices could slip below swelling tide lines. Experts from the nonprofit First Street Foundation also projected recently that properties in many coastal areas could lose value as flooding intensifies, a shift that could harm homeowners and erode local tax bases.
Scientists are not entirely on the same page about the causes driving the phenomenon, or whether the recent acceleration in rising seas will continue at such a rapid clip. Researchers typically prefer to rely on decades of data to be more certain of trends in the climate system, and their causes. In that context, the recent sea level rise has happened over a relatively short time period. That makes the trend as ambiguous as it is worrying.
Still, this much seems clear: The rapid sea level rise appears to start in the Gulf of Mexico, which has been warming far faster than the global ocean. Warm water naturally expands, causing sea levels to rise. That warm water also gets carried by currents out of the gulf and along the East Coast, affecting places such as Georgia and the Carolinas.
Will this trend continue? That remains less clear, scientists say.
The waters that have helped drive up sea levels in Gulf of Mexico are very warm even at deep levels, based on a preprint study by Jacob Steinberg and colleagues at the Woods Hole Oceanographic Institution, NASA’s Jet Propulsion Laboratory, the University of Hawaii at Manoa and the National Center for Atmospheric Research.
Steinberg and colleagues suggest that the trend implicates a warm current called the Loop Current, which enters the gulf from the Caribbean Sea and in turn is part of a broader pattern of circulation in the Atlantic Ocean.
