It's not just rising sea levels – the land major cities are built on is actually sinking, NASA images show
Rising sea levels are threatening the East Coast of the U.S., but that's not the only thing to worry about, according to NASA. Images shared by the space agency on Tuesday show the coast is actually sinking — including the land that holds major cities such as New York and Baltimore.
Coastal Cities at Risk of Sinking, NASA Findings Reveal
A recent study funded by NASA has discovered that the land beneath major cities along the East Coast of the U.S. is sinking. Satellite data and GPS sensors were used by a team of scientists at Virginia Tech's Earth Observation and Innovation Lab to monitor the motion of the coast. Their findings indicate that the land in cities like New York, Baltimore, and Norfolk has subsided by an average of 1 to 2 millimeters per year between 2007 and 2020. In some areas, the sinking rate was even two to three times faster.
The sinking land poses a significant threat to infrastructure, farmland, and wetlands that are vital for the millions of people residing along the coast. Notably, marshes have experienced a subsidence of over 3 millimeters per year, leading to the displacement of forests and the intrusion of saltwater. Moreover, approximately 897,000 structures including highways and airports are built on subsiding land, further exacerbating the risk.
The maps created using satellite data from various countries indicate that the Mid-Atlantic region is sinking at a higher rate, which can be attributed to the retreat of the Laurentide ice sheet. The ice sheet's retreat, dating back 12,000 years, has caused the region to sink downward. This sinking trend continues to this day and results in parts of the U.S. and Canada rising.
Charleston Faces Rapid Subsidence, Prompting Mitigation Measures
Among the cities experiencing the fastest sinking rates is Charleston, where the downtown area is a mere 10 feet above sea level. The city observes a subsidence of approximately 4 millimeters per year, with human activities like groundwater pumping playing a role in the sinking. To combat tidal flooding, city officials are contemplating the construction of an 8-mile-long seawall as a protective measure against storm surges.
While rising sea levels receive more attention, Leonard Ohenhen, a geophysicist at Virginia Tech, emphasized that subsidence is an overlooked yet pernicious issue. The consequences of subsidence include increased damage to coastal homes, infiltration of saltwater into farms and freshwater supplies, and other associated challenges. However, local efforts can slow down the rate of subsidence by addressing factors like groundwater extraction, dams, and other infrastructure contributing to the problem.
The Virginia Tech lab, in collaboration with NASA, intends to extend the research techniques to the Gulf Coast and ultimately map coastlines worldwide. By doing so, they aim to further understand and mitigate the risks associated with subsidence.
Unveiling a Threat Beyond Rising Sea Levels
The recent findings from NASA highlight the urgent need to address the sinking of coastal areas in addition to rising sea levels. The subsiding land poses significant risks to critical infrastructure, agriculture, and ecosystems that coastal communities heavily rely on. Efforts to slow down subsidence must be prioritized, as they can help mitigate the potential damages to homes, farmlands, and freshwater supplies.
As scientists continue to study and monitor the sinking land, it becomes clear that a comprehensive understanding of the factors contributing to subsidence is crucial. By mapping coastlines worldwide, researchers can develop effective strategies to protect vulnerable areas and ensure the long-term resilience of coastal communities.
