When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Climate change causes South Africa to mysteriously rise instead of sink. NASA helps find why Sayan Sen Neowin · May 10, 2025 19:14 EDT Image by Curioso Photography via PexelsScientists from the University of Bonn have discovered that South Africa is slowly lifting—by up to two millimeters per year—not because of deep underground activity, but due to a loss of water. The research, published in Journal of Geophysical Research: Solid Earth, suggests that severe droughts are causing the land to rise, challenging earlier ideas about mantle movement. South Africa has a network of GNSS (Global Navigation Satellite System) base stations that monitor land elevation. Between 2012 and 2020, data showed that parts of the country had risen by about six millimeters. Many scientists thought this was caused by mantle flow and dynamic topography, believing that a plume—a tube-like structure carrying hot material from deep inside Earth—was pushing the land upward. However, researchers led by Dr. Makan Karegar explored a different idea: Could drought-related water loss be responsible? The team studied daily GPS height data from 2000 to 2021, using singular spectral analysis (SSA) to filter out noise and focus on long-term trends. To understand the role of water in land movement, the team estimated water mass loading—how water weight affects the Earth's surface—using a grid system. They based their calculations on the Preliminary Reference Earth Model (PREM), which describes how the Earth responds to changes. The results showed a strong connection between water loss and land uplift. Data from NASA's GRACE (Gravity Recovery and Climate Experiment) satellite mission, which measures changes in gravity related to water storage, also supported this. Even though GRACE provides low-resolution readings, its data revealed that areas losing the most water were also rising the fastest. When comparing GPS-based water storage estimates with GRACE satellite data and hydrological models, the researchers found high correlations—up to 90% and 94% on a monthly scale across different regions. Long-term trends also matched up well, with correlations of 46% and 53%, giving further proof that drought-driven water loss is the main reason for South Africa’s uplift. The study explains that when water leaves the land, the surface expands—similar to how a foam ball regains its shape when you stop squeezing it. Before the droughts, underground water applied pressure that kept the land compressed. As these reserves dried up, the crust responded by rising. This discovery could help scientists track drought severity using GPS receivers, which provide accurate information on groundwater depletion. Since much of the world’s fresh water is stored underground, these measurements could give early warnings about water shortages. South Africa has faced major water crises, including the severe drought from 2015 to 2019, when Cape Town was close to "Day Zero", meaning taps could run dry. With climate change expected to alter rainfall patterns, the risk of future water shortages is high. According to Karegar, “This data also showed that the land uplift could primarily be explained by drought and the associated loss of water mass.” The researchers hope this method will help policymakers make better decisions about water use, especially in areas where supplies are running low. By studying how environmental changes affect the land, scientists can improve water management strategies and better prepare for future challenges. If droughts continue, South Africa’s gradual land uplift could become an even clearer warning sign of a worsening water crisis. Source: University of Bonn, American Geophysical Union This article was generated with some help from AI and reviewed by an editor. Tags Report a problem with article Follow @NeowinFeed