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Land Sinking Faster Than Seas Rise: New Flood Threat
28 Jan
Summary
- Human-driven land subsidence is now the main flood risk for millions.
- Land is sinking faster than sea levels are rising in many deltas.
- Groundwater extraction is a primary driver of accelerated land sinking.
A global study encompassing 40 major river deltas has identified human-driven land subsidence as the primary threat for millions facing coastal flooding. This sinking land is now a more significant risk than the sea-level rise long associated with climate change.
The research, published in Nature, utilized satellite data from 2014 to 2023. It found that every delta studied is experiencing subsidence, with over half sinking at an average rate exceeding 3 mm annually. In 13 deltas, including the Nile and Mekong, land is sinking faster than global sea levels are currently rising.
Human activities, particularly extensive groundwater extraction for urban and agricultural use, are accelerating this sinking process. Reduced sediment flow from dams and urban growth also contribute significantly. In many deltas, subsidence now contributes more to relative sea-level rise than ocean warming.
Millions living in low-lying delta regions, especially in South and Southeast Asia, are disproportionately affected. While subsidence is a local issue and potentially preventable through measures like groundwater regulation and sediment flow restoration, many of the most vulnerable deltas are in low-income countries with limited resources.
Scientists emphasize that mitigating subsidence is crucial alongside climate change efforts to safeguard coastal cities from displacement, food insecurity, and economic disruption.
