• River deltas are sinking faster than the sea is rising Earth’s river deltas, home to about 5% of the global population and some of the world’s major cities, are experiencing subsidence, which exacerbates the risks from sea-level rise. • The Copernicus Sentinel-1 mission has captured a decade’s worth of data showing land sinking faster than previously thought. • Ten of the world’s 34 biggest cities are built on river deltas and as such, these low-lying lands are often home to key infrastructure such as transport hubs that support trade links. • They are also critical rural and ecological zones that support both agriculture and biodiversity. • Some of the major delta cities include Kolkata (in the Ganges river delta), Alexandria (Nile), Shanghai (Yangtze), Bangkok (Chao Phraya), Ho Chi Minh City (Mekong) and New Orleans (Mississippi). • These cities and their surrounding lowlands are on the frontline of climate change.
Article Summaries:
- A new Nature study, based on a decade of Copernicus Sentinel‑1 radar data, shows that more than half of the world’s 40 major river deltas are subsiding at rates exceeding 3 mm per year-faster than the current global sea‑level rise. The research maps land‑elevation changes across deltas that host over 5 % of the global population, including cities such as Kolkata, Shanghai, Bangkok, Ho Chi Minh and New Orleans. It links accelerated sinking to human activities-excessive groundwater extraction, oil and gas exploitation, urbanisation, and upstream damming that alter sediment supply. The findings highlight that these low‑lying, densely populated regions face a heightened flood, salt‑water intrusion and storm‑surge risk.
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