Coastal cities in the Southern US are in even greater peril from sea-level rise than scientists already feared.
Scientists have been documenting an abnormal and dramatic surge in sea levels along the U.S. Gulf and Southeastern coastlines since about 2010, the Washington Post reports, 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.
In a study published in Nature Communications on April 10, 2023, researchers said they had detected rates of sea-level rise of about half an inch per year since 2010. They attribute the acceleration to the compounding effects of man-made climate change and natural climate variability.
To reach their conclusions, the authors studied a combination of field and satellite measurements since 1900, pinpointing the individual contributors to the acceleration, reports Phys.org.
“These rapid rates are unprecedented over at least the 20th century and they have been three times higher than the global average over the same period,” says Sönke Dangendorf, lead author and the David and Jane Flowerree Assistant Professor in the Department of River-Coastal Science and Engineering at Tulane.
“We systematically investigated the different causes, such as vertical land motion, ice-mass loss, and air pressure, but none of them could sufficiently explain the recent rate,” said Noah Hendricks, co-author and undergraduate student in Dangendorf’s team at his former institution, Old Dominion University in Norfolk, Virginia.
Hendricks also pointed out that “the acceleration is a widespread signal that extends from the coasts of the Gulf of Mexico up to Cape Hatteras in North Carolina and into the North Atlantic Ocean and Caribbean Seas, which is indicative of changes in the ocean’s density and circulation.”
Torbjörn Törnqvist, co-author and the Vokes Geology Professor in the Department of Earth and Environmental Sciences at Tulane notes that the rates will likely return to the more moderate values as predicted by climate models in the coming decades.
However, Professor Tornqvist also says, “This is no reason to give the all clear. “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.”
University of Arizona study
A University of Arizona study, published in the AMS Journal of Climate in March of 2023, provides an alarming new assessment of a key ingredient of the escalating climate emergency, particularly in popular but vulnerable areas of the US where millions of people live.
According to this study, reports The Guardian, there has been a dramatic surge in ocean levels along the same coastal areas as described in the Tulane study, with a sea level increase of almost 5in (12.7cm) since 2010.
This surge, or “burst” more than doubled the global average of 0.17in (0.44cm) per year, according to the National Oceanic and Atmospheric Administration (Noaa), due to a combination of sea level rise and storm surge.
And this surge is fueling ever more powerful cyclones, including Hurricane Ian, which struck Florida in September and caused more than $113 billion in damage – the state’s costliest natural disaster and the third most expensive storm in US history.
Existing projections by Nasa show a sea-level rise up to 12in (30cm) by the middle of the century, with longer-range forecasts even direr. The Gulf region from Texas to Florida, and the southern Atlantic seaboard will see most of the change, the agency says.
“The entire south-east coast and the Gulf Coast is feeling the impact of the sea-level rise acceleration,” said the study’s author Jianjun Yin, professor of geosciences at the University of Arizona.
“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.”
