Quantcast
Environmental News for a Healthier Planet and Life

Flood Risk Increasing for Atlantic Coast Cities

Popular
Rescue operations after Hurricane Harvey. Zachary West, Texas National Guard/Flickr

By Tim Radford

Cities on the Atlantic coast are likely to see more flooding. It won't just be catastrophic inundation, delivered by hurricane: it could also be routine, fine weather nuisance flooding.

And that will happen not just because of sea level rise, driven by global warming, but by another factor: in Virginia, North Carolina and South Carolina, the coastal lands are sinking, declining by up to three millimeters (approximately .12 inches) a year, according to a new study in Scientific Reports.


Long-term studies

The conclusion is backed up by analysis of two decades of global positioning satellite data, gravitational measurements from space and studies of groundwater traffic.

"There are primarily two reasons for this phenomenon," said Makan A Karegar, of the University of South Florida, and a guest researcher at the Institute of Geodesy and Geoinformation at the University of Bonn in Germany. "During the last ice age around 20,000 years ago, large parts of Canada were covered by an ice sheet. This tremendous mass pressed down on the continent."

The weight of the ice depressed the mantle beneath the planet's crust, and in consequence tracts of land not covered by ice were uplifted.

"When the ice sheet then melted, this process was reversed," Karegar said. "The East Coast has thus been sinking back down for the last few thousand years."

But what geophysicists call isostatic adjustment may not be the only force at work. When cities and farmers abstract groundwater, they also depress the soil around them. Water keeps the earth underfoot more buoyant. Take the water away, and the mass of the rocks and soil is more easily compressed.

'Nuisance' floods

The cities along the Atlantic coast were first settled 300 to 400 years ago: in those centuries they have probably sunk by 45 centimeters (approximately 18 inches), as a consequence of the loss of ice cover. But because of global warming, the seas are rising by three millimeters (approximately .12 inches) or more a year, placing coastal settlements at increasing risk.

Researchers have warned, repeatedly, of potential catastrophic flooding potentially driven by more violent windstorms and calculated that climate change could trigger massive exodus from the coast by climate refugees. But for reasons that may have nothing to do with global warming driven by the profligate combustion of fossil fuels, oceanographers have also identified highwater "hotspots" along the Atlantic coast that could substantially increase risks.

The upshot is that many coastal cities will increasingly face a greater frequency of "nuisance" floods. Already, rising waters have claimed 15 centimeters (approximately 5.9 inches) of parts of the Atlantic coast. Global warming will accelerate the process.

"Even if the removal of groundwater is reduced, the number of floods will thus continue to increase," said Karegar. "The sums of money that need to be spent to rectify the damage associated with this will also increase significantly. One should, therefore, assume that the USA has a vested interest in combating climate change with all its resources."

Reposted with permission from our media associate Climate News Network.

EcoWatch Daily Newsletter

A pangolin at a rescue center in Cambodia. Rhett A. Butler / Mongabay

By Malavika Vyawahare

China has banned the trade and consumption of wild animals in the wake of the coronavirus outbreak that has claimed more than 2,700 lives and infected more than 81,000 people, most of them in China, according to the state-run Xinhua News Agency.

Read More
A man carries plastic shopping bags in Times Square on May 5, 2018 in New York City. Kena Betancur / VIEWpress / Corbis / Getty Images

Nearly one year after New York became the second state in the nation to pass a ban on grocery store plastic bags — the law is going into effect on Sunday.

Read More
Sponsored
White gold man-made diamond solitaire engagement ring. Clean Origin

While keeping track of the new trends in the diamond industry can be hard, it is still an essential task of any savvy consumer or industry observer. Whether you are looking to catch a deal on your next diamond purchase or researching the pros and cons of an investment within the diamond industry, keeping up with the trends is imperative.

Read More
Rep. Alexandria Ocasio-Cortez (D-NY) (C) chants with housing and environmental advocates before a news conference to introduce legislation to transform public housing as part of her Green New Deal outside the U.S. Capitol Nov. 14, 2019 in Washington, DC. Chip Somodevilla / Getty Images

Rep. Alexandria Ocasio-Cortez (D-N.Y.) took to the floor of the House of Representatives yesterday to chide Republicans for not reading the Green New Deal, which she introduced over one year ago, as The Hill reported. She then read the entire 14-page document into the congressional record.

Read More
Anti Ivan Duque's demonstrator is seen holding a placard with the photos of social leader Alirio Sánchez Sánchez and the indigenous Hector Janer Latín, both killed in Cauca, Colombia during a protest against Ivan Duque visit in London which included a meeting about fracking, environmental issues, the peace process implementation, and questioning the risk that social leaders in Colombia face. Andres Pantoja / SOPA Images / LightRocket / Getty Images

Colombia was the most dangerous nation in 2019 to be an environmental activist and experts suspect that conditions will only get worse.

Read More