The 28 most populous cities in the United States are all at least partly sinking. That’s according to a new study from the Columbia University Climate School. Researchers used U.S. census data from 2020 to pinpoint the country’s most populous cities, which, combined, are home to roughly 39 million people or 12% of the U.S. population. The list includes 11 coastal cities, eight riparian (sitting alongside rivers) and nine inland cities. Nearly half the locations on this list are among the country’s fastest-growing cities. To create high-resolution maps of each city over time, researchers analyzed more than 2,500 satellite radar images between 2015 and 2021. They created roughly 400 precise images for each city that allowed them to compare vertical land movement over the study period. Previous studies have looked at sinking land but at a scale that made it difficult to identify specific areas and infrastructure at risk. The Columbia study is the first to provide fine-scale information that city planners can use to protect infrastructure at risk. Natural processes can account for some of the land movement, but researchers found “most of the sinking land results from human-driven activities, with 80% of the subsidence associated with groundwater withdrawals,” the study authors write. Essentially, as groundwater is removed, the soil pressure changes and allows for more sinking. Similarly, oil and gas extraction are also factors. Fossil fuel extraction and long-term dependence on groundwater combine to make Houston, Texas, the fastest-sinking city in the country; 42% of its land area…This article was originally published on Mongabay

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