Quantcast
Environmental News for a Healthier Planet and Life

Flood Risk Increasing for Atlantic Coast Cities

Popular
Flood Risk Increasing for Atlantic Coast Cities
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.

A dugong, also called a sea cow, swims with golden pilot jacks near Marsa Alam, Egypt, Red Sea. Alexis Rosenfeld / Getty Images

In 2010, world leaders agreed to 20 targets to protect Earth's biodiversity over the next decade. By 2020, none of them had been met. Now, the question is whether the world can do any better once new targets are set during the meeting of the UN Convention on Biodiversity in Kunming, China later this year.

Read More Show Less

EcoWatch Daily Newsletter

President Joe Biden signs executive orders in the State Dining Room at the White House on Jan. 22, 2021 in Washington, DC. Jabin Botsford / The Washington Post via Getty Images

By Andrew Rosenberg

The first 24 hours of the administration of President Joe Biden were filled not only with ceremony, but also with real action. Executive orders and other directives were quickly signed. More actions have followed. All consequential. Many provide a basis for not just undoing actions of the previous administration, but also making real advances in public policy to protect public health, safety, and the environment.

Read More Show Less

Trending

Melting ice forms a lake on free-floating ice jammed into the Ilulissat Icefjord during unseasonably warm weather on July 30, 2019 near Ilulissat, Greenland. Sean Gallup / Getty Images

A first-of-its-kind study has examined the satellite record to see how the climate crisis is impacting all of the planet's ice.

Read More Show Less
Probiotic rich foods. bit245 / iStock / Getty Images Plus

By Ana Maldonado-Contreras

Takeaways

  • Your gut is home to trillions of bacteria that are vital for keeping you healthy.
  • Some of these microbes help to regulate the immune system.
  • New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.

You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.

Read More Show Less
Michael Mann photo inset by Joshua Yospyn.

By Jeff Masters, Ph.D.

The New Climate War: the fight to take back our planet is the latest must-read book by leading climate change scientist and communicator Michael Mann of Penn State University.

Read More Show Less