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- The lands flow along the mid-Atlantic coast due to subsidence of lands dating from the glaciation.
- Thus, the sea level caused by humans will have increased twice as fast as the world average over the coming decades.
The lands flow along the Mid-Atlantic coast, which will cause a rise in the sea level caused by man twice higher than the world average in the coming decades for towns and villages that have elected home in this region, according to a recent study.
The Laurentide Ice Sheet pushed back to the south from the Arctic between 20,000 and 95,000 years ago during the last ice age, the researchers noted in their study published late last year in the journal Nature. In front of the imposing layer of ice, the lands have also been pushed into what scientists call a "glacial frontbulge".
When the ice melted, the land began to grow or weaken and continue to settle in the area. Subsidence makes the sea level rise much higher than on other coasts.
"In New England, there is not too much extra sea level rise Peter Huybers, co-author of the study and professor of Earth and Planet Sciences at Harvard University, said in a press release. "The ice cap explosion was centered on the central Atlantic and, as it is still stabilizing, the relative rise in sea level in the central Atlantic is about twice the global average. . "
Scientists, who used "everything from tide gauges to GPS data to paint a more accurate picture of sea level rise along the east coast," said the cities called by the center Atlantic coast will have to prepare not only for elevation of sea level caused by the increase in the rate due to the natural subsidence of the land.
"The fact that the middle of the Atlantic sinks due to long-term geological processes means that it will continue for centuries and millennia, in addition to any other change in the level of the sea, "said Huybers. "Central Atlantic already faces regular coastal flooding and this problem will only get worse.
The Hampton Roads area at the mouth of Chesapeake Bay is particularly vulnerable to high tides and coastal flooding. A network of GPS stations, operated by the National Geodetic Survey, has tracked land subsidence in Maryland and Virginia. for several decades, the quarterly reports of Chesapeake.
Researchers using the data collected estimate that the land around the bay is dropping by about 1.5 millimeters a year. The Hampton Roads area appears to be falling faster, at a rate of 4 millimeters per year.
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Other studies have suggested that declining numbers in the area, especially around Chesapeake Bay, is also the result of human activities.
A report published by the US Geological Survey in 2013 determined groundwater abstraction by municipal utilities and other users exacerbate the landslide.
In the report, USGS hydrologist Jack Eggleston and his colleague Jason Pope discovered that the fastest-growing areas in the Chesapeake Bay area coincide with the largest amount of groundwater pumped. In fact, Eggleston and Pope estimate that groundwater withdrawals have accounted for about half of the subsidence in recent decades.
"The most relevant subsidence causes for the southern Chesapeake Bay area include compaction of the aquifer system caused by groundwater withdrawals and glacier isostatic adjustment," the scientists wrote. in the report.
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