New data details the risk of sea level rise for US coastal cities

A new study of sea level rise, using detailed data on changes in land elevation, has found that current scientific models may not accurately reflect vulnerabilities in 32 coastal cities in the United States.

The analysisPublished Wednesday in Nature, uses satellite images to detect sinking and rising land to paint a more accurate picture of flood exposure, both today and in the future.

Nearly 40 percent of Americans live along the coast, where subsidence or sinking land could significantly increase the threat of sea level rise. While the Gulf Coast is experiencing many of the worst cases of subsidence — parts of Galveston, Texas, and Grand Isle, La., are sinking into the ocean faster than global average sea levels are rising — the trend is reflected across the United States find. Coast of States.

Many commonly used sea level projections take land subsidence into account by looking at long-term trends derived from data collected by tide gauges, even though the locations are miles away from population centers. “They often represent just measurements at a single location of how the ground is moving,” and not the overall spatial dynamics of the entire city, says Leonard Ohenhen, a Ph.D. candidate at Virginia Tech and lead author of the paper.

The work of Mr Ohenhen, Manoochehr Shirzai, Chandrakanta Ojha and colleagues reveals how land along the coast is sinking into the ocean, further exacerbating the danger of global sea level rise. The new study extends their analysis of elevation changes along the Atlantic coast to the Gulf and the West, and uses these maps to examine potential flooding in major coastal cities in more detail.

“This will help improve accuracy on the decadal time scale because it provides much higher spatial resolution,” said Bob Kopp, a climate scientist at Rutgers University who helped review the new paper for Nature.

However, the study assumes that the trends observed during the relatively short satellite record, from 2007 to 2020, can be extrapolated into the future at a constant rate. This may apply in areas that are sinking due to natural causes. But human activities, such as the extraction of groundwater or oil and gas, are a key factor in land subsidence in many places.

“Groundwater retreat is a major reason why Atlantic City is sinking faster than New York City,” says Dr. Kopp. “Can you assume they will continue at their current pace for 30 years? Maybe. Can you assume that this can be done for 100 years? I probably wouldn’t do that.”