Sea Levels Far Higher Than Predicted, Studies Reveal

Two new studies reveal that global sea levels are significantly higher than previously estimated, and coastal lands are subsiding faster than realized, dramatically increasing flood risks for tens of millions. Katharina Seeger and Philip Minderhoud of Wageningen University analyzed tidal gauge data from 385 locations, finding actual sea levels average 9.4 to 10.6 inches above model-based estimates. Their work shows about 80 million people live on land below sea level—nearly double earlier figures. Leonard Ohenhen of UC Irvine used satellite radar to map subsidence on 40 major river deltas, finding that in 18 deltas sinking rates exceed sea level rise, effectively doubling or decupling local sea level increases. Affected areas include the Nile, Mekong, Mahanadi, and Yellow River deltas. Parts of Shanghai have sunk over 6 feet, Bangkok over 5 feet, and Osaka and Tianjin around 10 feet. Jakarta has sunk up to 13 feet since 1970, prompting Indonesia's 2019 decision to move its capital. The studies highlight that past research relied on flawed geoid models that ignore ocean dynamics, leading to systematic underestimation of risks. Researchers call for urgent action, noting subsidence can be halted locally by ending groundwater pumping, as demonstrated by Tokyo's stabilization after banning pumping.