[Rockhounds] As sea levels rise, the East Coast is also sinking

[Kreigh Tomaszewski]

Climate scientists already know that the East Coast of the United States
could see around a foot of sea-level rise
<https://www.wired.com/story/sea-level-rise-will-be-catastrophic-and-unequal/>
by
2050, which will be catastrophic on its own. But they are just beginning to
thoroughly measure a “hidden vulnerability” that will make matters far
worse: The coastline is also *sinking*. It’s a phenomenon known as
subsidence, and it’s poised to make the rising ocean all the more
dangerous, both for people and coastal ecosystems.

New research published <https://www.nature.com/articles/s41467-023-37853-7> in
the journal Nature Communications finds that the Atlantic coast—home to
more than a third of the US population—is dropping by several millimeters
per year. In Charleston, South Carolina, and the Chesapeake Bay, it’s up to
5 millimeters (a fifth of an inch). In some areas of Delaware, it’s as much
as twice that.

Five millimeters of annual sea-level rise along a stretch of coastline,
plus 5 millimeters of subsidence there, is effectively 10 millimeters of
relative sea-level rise. Atlantic coastal cities are already suffering
from persistent
flooding <https://www.wired.com/story/the-tide-is-high-and-getting-higher/>,
and the deluge will only get worse
<https://www.nature.com/articles/s41598-021-01096-7> as they sink while
seas rise. Yet high-resolution subsidence data like this isn’t yet taken
into account for coastal hazard assessments. “What we want to do here is to
really bring awareness about this missing component, that based on our
analysis actually makes the near-future vulnerability a lot worse than what
you would expect from sea-level rise alone,” says Manoochehr Shirzaei, an
environmental security expert at Virginia Tech and coauthor of the new
paper.

https://arstechnica.com/science/2023/04/as-sea-levels-rise-the-east-coast-is-also-sinking/