Study Warns of Largest US Cities To Face 'Significant Flooding'

Sinking U.S. cities are more vulnerable to sea-level rises, scientists have found.

New research published in Nature found that one in 50 people living in coastal cities are at risk of "significant flooding" by 2050.

To reach these findings, researchers at Virginia Tech combined satellite measurements of sinking land in 32 U.S. cities across the Atlantic, Pacific and Gulf coasts, with projections of sea level rise.

They found that several major cities in the U.S. are most at risk. These are Miami; New Orleans; Port Arthur, Texas; Foster City, California, and Savannah, Georgia.

In the next 30 years, 500,000 people could be seeing the direct result of sea level rise, while one in 35 properties could be severally damaged by flooding.

Global warming is causing a rise in sea levels, leaving coastal areas at risk. Over 90 percent of the ocean is estimated to be absorbing greenhouse gases in the atmosphere, which is also causing sea water to expand. And, as the world warms, glaciers and ice sheets are melting, feeding into the world's oceans.

"We need to develop both adaptation and mitigation strategies. Our finding shows that land subsidence will be the main driver of coastal flooding through 2050," associate professor Manoochehr Shirzaei at Virginia Tech's Earth Observation and Innovation Lab told Newsweek. "Thus, we must act quickly to slow down or reverse land subsidies in hot spots. Some of the key mitigation strategies include managed aquifer recharge and supplying sediments to the coast to reduce subsidence due to aquifer and sediment compaction. Such measures can become effective fairly quickly and give us additional time to prepare for the flooding caused by climate change-driven sea level rise."

Current projections are estimating that waters around U.S. coastal cities are expected to rise at a faster rate than the global average, the new study reports. And these cities are home to 30 percent of the U.S. population.

"[These findings] are concerning, since we are looking at 30-year time frame, which is relevant to policy dictions," Shirzaei said. "We show that if no adaptation and mitigation plans are created, by 2050 many coastal cities will face significant flooding."

"One of the challenges we have with communicating the issue of sea-level rise and land subsidence broadly is it often seems like a long-term problem, like something whose impacts will only manifest at the end of the century, which many people may not care about," lead author Leonard Ohenhen, a graduate student working with Shirzaei at Virginia Tech's Earth Observation and Innovation Lab, said in a statement. "What we've done here is focused the picture on the short term, just 26 years from now."

The researchers state that if no effective flood prevention structures are implemented in time, there could be devastating consequences.

This study also sheds light on how certain racial and demographics could be more adversely affected. Some most at risk areas, particularly along the Gulf Coast, will see racial minorities most affected.

Properties facing risk of destruction due to the rising sea levels are generally lesser value, the study reported, and these two demographics often intertwine.

"That was the most surprising part of the study," Ohenhen said in a statement. "We found that there is racial and economic inequality in those areas in that there was an overrepresentation of historically marginalized groups potentially impacted as well as properties with significantly lower value than the rest of the cities. It really multiplies the potential impact to those areas and their abilities to recover from significant flooding."

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