CBS Local — While the flood waters from monstrous hurricanes like Harvey and Irma eventually recede, a new study says that a bigger issue is that flooding is poised to become an every day problem for many coastal cities as the land there continues to sink into the Atlantic Ocean.
According to a study published in Nature’s Scientific Reports, sea levels on the east coast of the United States rise approximately three millimeters per year. While that may not sound like much, bear in mind, sea levels have risen roughly two feet since the 16th century and are poised to rise at a quicker rate as super storms continue to form and ice caps continue to melt.
While the melting ice caps and storms ravaging the coast line — ultimately causing erosion — are concerns, another reason the coastline is sinking is due to post-glacial isostatic rebound, Forbes says.
Here’s the explanation, from Forbes’ Trevor Nace:
Imagine you’re in a swimming pool with a floating noodle and you push down on the center of the noodle (ice weighing down the continent). On either side of where you pushed down, the noodle will pop up a bit to compensate for the load. This same process happens on Earth when it experiences a large heavy load such as a glacier. So the glaciers on the North American continent caused the east coast to pop up a bit due to the load.
However, once the glaciers melt, the weight on the continent is removed and the edges fall back down. Similar to if you removed your hand from a noodle you’d notice the popped up portions on either side of your hand will move downward. This gradual and slow rebounding or lowering of the continent after being pushed up from a glacier is called isostatic rebound. This has resulted in the east coast of America to slowly but steadily sink relative to the Atlantic Ocean.
In addition to those reasons, the third reason Forbes lists for why the east coast is sinking is due to humans’ use of ground water in coastal communities. Per the report, using and removing water from the soil that helps hold up sediment and rock causes the land to collapse in on itself since it can’t support its own weight anymore.
Hurricanes also cause extensive erosion to beaches and coastal communities and in some cases the more severe effects of the storms aren’t revealed until years later.
In addition to immediate erosion, hurricanes — due to their powerful winds and storm surges — can greatly weaken coastal lands and cause instability at their core, leading to landslides and a permanent loss of coastline.
With three distinct factors working against us, and increasingly stronger storms, experts expect the U.S. coastline to be drastically reshaped within the next hundred years or so.