South Africa's Coast Is RisingAnd Scientists Have a New Explanation Why

"For decades geologists thought the slow rise of South Africa's southern coast was driven by forces deep belowbuoyant plumes of molten rock ascending through Earth's mantle and heaving the crust upward over millions of years. But now satellite data and precise GPS measurements are tilting such assumptions off their axis. A study in the Journal of Geophysical Research: Solid Earth suggests this land rise may have less to do with deep tectonic forces and more to do with missing groundwater just under our feet."

"Human activity has long been depleting South Africa's groundwater. In 2018, after grappling with severe droughts for years, the country came close to a full-blown water emergency when Cape Town was nearly the world's first major city to literally run out of watera scenario dubbed Day Zero. For several months that year the city's residents faced the very real prospect of having to regularly queue for critically limited water supplies, an outcome staved off only by timely rainfall and intensive water-saving campaigns."

"The recent study hypothesizes that the ground, once compressed by the sheer weight of the surface water and groundwater above it, is now expanding like a foam mattress relieved of pressure. Using GPS and satellite gravity data from between 2000 and 2021, the researchers detected a roughly six-millimeter rise in the land surfacea shift that coincides with humans' depletion of South Africa's water reserves and periods of drought."

For decades geologists attributed slow uplift of South Africa's southern coast to buoyant mantle plumes heaving the crust over millions of years. Satellite and GPS measurements from 2000–2021 detect roughly six millimeters of surface uplift along that coast. Long-term human extraction of groundwater and severe droughts have drained aquifers and reduced surface water, removing mass above the crust. The crust responds elastically to unloading, producing measurable uplift like a foam mattress expanding when pressure is released. Historic near-crisis water shortages such as Cape Town's 2018 Day Zero emergency reflect the combined effects of climate-driven drought and unsustainable water use that depleted reservoirs and aquifers.

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