Why hundreds of cities across the globe are sinking

The ground on which many urban areas rest is subsiding" or sinking lower into the earth - a phenomenon frequently linked to water extraction. A study out this month by a research team in China used satellite imaging to track this sinkage across nearly 500 major cities across the globe. It found that much of this so-called land subsidence" is happening under Asian metropolises. To unpack how cities are sinking and why, The World's Host Carolyn Beeler spoke to Robert Nicholls, a professor of climate adaptation at the University of East Anglia in the UK.