Alarming new predictions show how America’s iconic coastal cities could soon be swallowed by the ocean

Millions of people living in US coastal cities could see their homes sink into the ocean in the coming decades, a study warns.

Researchers at the US Geological Survey (USGS) predict that the East Coast will be devastated by rising sea levels, flooding and sinking land by 2100.

They estimate that if sea levels rise by four feet by 2100, as the United Nations has predicted, more than 14 million Americans will be affected in places like Norfolk, Virginia, Miami, Florida and New York City.

They estimate this would cost more than $1 trillion in property damage and cause the region to lose up to 80 percent of its beaches.

Meanwhile, a separate study found that California’s massive water needs are causing parts of the state to sink at record rates.

Researchers at Stanford University found that the San Joaquin Valley is sinking at a rate of almost an inch per year.

The phenomenon, called subsidence, is often caused by the removal of water, natural gas or mineral resources from the ground.

When water is continually withdrawn from the Earth’s surface and not replenished, it causes sediments to compress, damaging aqueducts and permanently altering aquifers.

“There are two amazing things about the subsidence in the valley,” says study co-author Rosemary Knight.

‘First, there is the magnitude of what happened before 1970. And the second is that it’s happening again today.”

Millions of people along the southeast Atlantic coast will be displaced by 2100 due to rising sea levels, land subsidence and flooding

USGS reported that 70 percent of the East Coast population will be exposed to shallow or emerging groundwater by the end of the century due to rising sea levels, while coastal storms and hurricanes will increase flooding.

Rising sea levels are mainly caused by global warming, which is causing the ocean to warm and glaciers to melt, while the Gulf Stream pushes more water onto the coastline.

Since 1920, sea levels have risen between 6 and 8 inches, but due to global warming and federal government agencies including the Department of Homeland Security and the USGS predicts between 2020 and 2100 they will rise another four feet.

Rising sea levels will vary depending on the coast, with the East Coast seeing 10 to 14 inches between 2020 and 2050, while the West Coast will see a rise of 10 to 20 inches in that time frame.

The government report also states that major floods are expected to occur five times as often over the next thirty years as in 2020.

Roughly 80 million people live on the south-east coast and experts say half will be affected by flooding alone, according to the research published in Nature Climate change.

The team warned that rising water levels will lead to major damage to infrastructure, including roads, buildings and septic systems.

The study’s co-author, Manoochehr Shirzaei of Virginia Tech’s Department of Geosciences, said: ‘We need to rethink how we plan and build for the future, especially in highly vulnerable coastal areas.

“By incorporating a broader range of climate hazards into resilience strategies, we can better protect our communities from the compound effects of sea level rise and extreme weather.”

However, the researchers did not indicate what strategies should be implemented to prevent the East Coast from further sinking.

The USGS also reported that subsidence is causing much of the land on the southeastern Atlantic coast to sink, which will only worsen rising sea levels.

Cities most exposed to notable sinking land are Miami, Savannah, Charleston, Myrtle Beach, Virginia Beach and Norfolk.

This map shows how much the coastline will be affected by coastal flooding, sinking land and rising sea levels

California’s groundwater has been significantly reduced due to redistribution across the US due to severe droughts. In the photo: a new dug canal (left) was constructed next to the Friant-Kern Canal (right) after it had shrunk by 60 percent due to subsidence

According to the study, 1.3 million people currently live in these areas where land subsidence exceeds two millimeters per year.

Similarly, researchers found that this is already beginning to occur at drastic levels in California’s San Joaquin Valley, damaging local wells and irrigation systems.

The San Joaquin Valley’s arid climate and a series of droughts have made it necessary to pump groundwater to support large agricultural lands in the U.S., causing permanent changes to the valley’s topography.

Researchers at Stanford estimate that approximately 220 billion liters of water are needed annually to prevent further subsidence.

When water is withdrawn from natural reservoirs called aquifers, it causes the land to lose its shape and sink.

This is because aquifers contain sediments that have pores, much like a sponge, and when water is not replenished, these spaces will be compressed and permanently alter the ability to transport water.

This is seven billion gallons less than the amount of surface water left annually in the San Joaquin Valley after all other environmental needs have been met.

However, Knight said she is hopeful that steps can be taken to prevent the country from continuing to sink.

“My group and others have been studying this problem for some time, and this study is a key part of figuring out how we can tackle it sustainably,” she said.

The researchers tracked elevation changes in the San Joaquin Valley using satellite technology called interferometric synthetic aperture radar (InSAR).

The system noticed the changes by transmitting radar signals from Earth’s orbit and analyzing the reflections to measure how much the ground had shifted between 2006 and 2022.

Maps show the period of subsidence in the San Joaquin Valley. The left image shows the areas where it sank between 2006 and 2010 and the right image shows the subsidence from 2015 to 2022

For the past two decades, researchers have known the valley was sinking, but this is the first time they used satellite radar systems to confirm it.

Although there was a gap in the data between 2011 and 2015, the team was able to estimate how much the land sank before and after that time frame.

From 2006 through 2010, they reported that the San Joaquin Valley sank by 4.2 cubic feet and another 2.8 cubic feet between 2015 and 2022.

‘How much have last year’s floods worsened? How much do farmers spend to re-level their land? Many of the costs of land subsidence are not well known,” emphasizes Matthew Lees, lead author of the study.

Their findings mirror a similar event that occurred between 1925 and 1970, when groundwater pumping caused more than 4,000 square kilometers to drop dramatically by up to 30 feet.

According to the study published in the journal Communication Earth and environmentthe researchers recommend the implementation of a flood-managed aquifer recharge (flood-MAR).

This would strategically divert excess water from rain and snowfall to replenish groundwater in sinking areas.

“We need to focus on the places where subsidence will cause the greatest social and economic costs,” Knight explained.

‘So we look at places where subsidence can, for example, damage an aqueduct or household wells in small communities.

“By taking this perspective at the Valley scale,” Knight added, “we can begin to focus on feasible solutions.”