In Jakarta, parts of the city are sinking by as much as 25 centimeters per year, according to the National Research and Innovation Agency, Indonesia. This rate of land subsidence far exceeds global sea-level rise, dramatically accelerating coastal flooding and often overshadowing global sea-level rise alone. Accurate satellite maps are essential to understand these sinking coastlines.

Governments and international bodies are investing heavily in climate change adaptation for sea-level rise, but many coastal cities are simultaneously sinking due to local factors. This effectively doubles their exposure to flooding. Yet, many coastal cities underestimate their true vulnerability, misallocating adaptation funds by failing to integrate rapid land subsidence rates into their planning.

Without integrating precise land subsidence data and shifting local resource management, many coastal regions face significantly more severe and frequent flooding than currently predicted, leading to unprecedented infrastructure damage and displacement. Globally, land subsidence already contributes to over half of the relative sea-level rise in many coastal megacities, according to Science Advances, 2021. Fortunately, advanced satellite technology like InSAR can now measure ground movement with millimeter precision, offering a critical tool to address this hidden threat, as reported by the European Space Agency.

The Sinking Ground Beneath Our Feet

Who is truly bearing the brunt of this hidden crisis? The impacts of subsidence are not evenly distributed, hitting vulnerable populations and critical economic hubs hardest, creating a growing humanitarian and economic crisis.

  • An estimated 635 million people globally live in coastal areas vulnerable to subsidence and sea-level rise, with a significant portion in Asia, according to Nature Communications, 2022.
  • Low-income communities and informal settlements built on unstable ground are often disproportionately affected by subsidence-induced flooding, according to UN-Habitat.
  • Major port cities like Houston, New Orleans, and Venice have experienced significant historical subsidence, exacerbating flood risks and infrastructure damage, as reported by the USGS and the Italian National Research Council.
  • Agricultural regions relying heavily on groundwater pumping, such as California's Central Valley, have seen land sink by several meters over decades, according to NASA JPL.