A new study shows that coastal communities may be more at risk from sea level rise than previously thought. This could have profound implications for real estate, infrastructure, and the US economy.
Sea levels rise as the Earth warms and glaciers melt. At the same time, the Earth is sinking – another harmful consequence of climate change. According to a new study by Virginia Tech and the US Geological Survey, it is sinking up to five millimeters annually in some areas. Sea level rise is about three millimeters per year.
“What we found is that most of the land across the United States, and indeed globally, is subsiding, falling. And this downward movement is increasing the rate of relative sea level rise in many locations around the world, specifically along the coast,” Manouchehr Sherzai said. Associate Professor of Geophysics and Remote Sensing at Virginia Tech: “East Coast of the United States.”
Sherzai and his team used space-based radar satellites to build digital maps of the Earth over many years to see which places are sinking the most. They then built the first high-resolution maps of this, showing East Coast land sinking anywhere from 2mm to 5mm per year – affecting more than 2 million people and 800,000 properties.
When you add sinking land to sea level rise, the study says, it doubles the frequency of floods and halves the time cities and coastal residents have to prepare. This has consequences for flood adaptation strategies that have already been developed. Areas, including New York's JFK and LaGuardia airports, are seeing ground subsidence at a rate of more than 2 millimeters per year.
“So, with sea levels rising, for example, at a rate of five millimeters per year, we have
In Baltimore, Maryland, so-called nuisance flooding is becoming more common, due to sea levels rising and land sinking.
“When you have nuisance flooding, it basically means it's nuisance,” said Grace Hansen, a coastal planner for the city of Baltimore. “But when you consider that the park here is flooded, some people can't get to work or can't get to work.”
According to the study, Baltimore's coastal area is sinking by more than two millimeters annually.
“And to you and me, that doesn't seem like much by any means, but what becomes a problem is when it's not uniform, and the foundation of the building can be sinking faster than the other side of the building, and that's where,” Hansen said, “I'll see that the foundation unstable”.
Why does the earth sink?
Climate change is causing drought, forcing us to pump more groundwater and build more dams to store water.
“Rising temperatures and lower rainfall increase the demand for fresh water and the main source of that in most places is groundwater. So we pump groundwater to meet this demand and this leads to accelerated land subsidence or sinking of the land due to soil pressure,” explained Sherzai: “Aquifer “underground.”
In addition, dams are built to provide water and generate electricity. In light of the transition to clean energy, the demand for electricity is increasing significantly. These dams reduce the supply of sediment to coastal areas and starve them. As a result, the Earth sinks even more.
“In terms of groundwater extraction, that's primarily one of the reasons Baltimore is sinking,” Hansen said.
More than six dams surround Baltimore.
Even as water scarcity increases, Sherzai says we need to mitigate land sinking in the next decade, otherwise it will severely impact the safety of buildings and infrastructure.
He added: “This will affect bridges, pipelines, railways and airport runways, and this will translate into losses and repair costs in the trillions of dollars.”
Some of Sherzai's suggestions include recycling water by treating sewage and sewage, setting broader restrictions on water use, especially in landscaping, and better capturing and storing rainwater. Ă‚ One project in Virginia pumps groundwater back into aquifers and treats it in wastewater plants.
Whatever the choice, he says, the sinking must stop.
CNBC senior producer Erica Posey contributed to this article.
