“Slowly but surely”: Large parts of the US east coast are sinking Block children are back with their father in Denmark, police say

Year after year, sea levels are rising, increasing the risk of flooding for coastal areas and their inhabitants around the world. Research now shows that large swaths of land along the US east coast are sinking at the same time – in some cases significantly.

Densely populated cities such as New York, Baltimore and Norfolk are also affected. There, ground movement not only increases the risk of flooding, but also threatens the sometimes dilapidated infrastructure: buildings, pipelines, roads, railway lines and even runways at major airports.

“The problem is not just that the country is sinking,” explains lead author Leonard Ohenhen of the University of Virginia Tech in Blacksburg. “The problem is that the hotspots of the sinking country overlap directly with population and infrastructure centers.” The geoscientist and his colleagues in the journal “PNAS Nexus” cite the major New York airports JFK and LaGuardia as examples, where the annual subsidence rate is more than two millimeters.

The risk of flooding is increasing

For the entire US east coast, the team evaluated ground movements along a 100 kilometer wide strip using radar measurements from satellites for the period from 2007 to 2020. Results: Large parts of the area are sinking at more than two millimeters per year, some – up to 3,700 square meters kilometers – by more than 5 millimeters, and in some places even by more than 10 millimeters. In New York, Baltimore and Norfolk the rate is predominantly one to two millimeters per year. The main causes are the compaction of the subsurface, the extraction of groundwater and mining.

Land subsidence, combined with rising sea levels – currently around 4 millimeters per year – could triple the risk of flooding for some areas within decades, the group writes. Even if sea levels did not rise, continued subsidence in some coastal areas could lead to irreversible flooding and more frequent flooding. (sda/dpa)