The land under South Africa is rising every year. We finally know why.
Drought and water loss caused South Africa to rise an average of 6 millimeters (0.2 inches) between 2012 and 2020, according to a new study.
Scientists have developed a new model to measure this land uplift and associated water loss using global positioning system (GPS) data. In South Africa, they found that uplift patterns correlated with droughts and with seasonal shifts between dry and wet seasons. The GPS-based model could help researchers spot signs of drought in the future, the researchers suggest.
Scientists have known for more than a decade that South Africa is rising. Initially, some suspected the uplift was caused by a plume of hot rock in the mantle, Earth's middle layer, that sits beneath the country. A mantle plume forms when hot material from deep in the mantle rises and pushes against the lithosphere (the crust and upper mantle), lifting the land above it.
But Makan Karegar, a geodesist at the University of Bonn in Germany, noticed that data showing uplift in South Africa correlated with periods of drought. In particular, Karegar and his colleagues spotted a pattern of uplift that corresponded to the intense "Day Zero" drought South Africa faced between 2015 and 2018, when the city of Cape Town was at risk of needing to shut off the municipal water supply. "We started to think there should be a link between this pattern and water loss," Karegar told Live Science.
To investigate this relationship further, the team collected GPS data from permanent stations scattered throughout South Africa. These stations can precisely measure changes in height over time, down to fractions of a millimeter per year. In the new study, published April 9 in the Journal of Geophysical Research: Solid Earth, the scientists developed a model linking this uplift to changes in the country's water storage.
Related: Africa is being torn apart by a 'superplume' of hot rock from deep within Earth, study suggests
As water disappeared from surface reservoirs, soil, and groundwater reserves, the land rose, like memory foam does after a weight is removed. The researchers observed some regional and seasonal variations in height, as well as some long-term variability. But overall, between 2012 and 2020, South Africa rose an average of 6 mm in response to water loss, the team found. Some areas near depleted water reservoirs rose as much as 0.4 inches (10 mm) during the drought.
"The biggest surprise for us was that we saw an uplift over most parts of South Africa," study coauthor Christian Mielke, a geodesist at the University of Bonn, told Live Science. "We were expecting that this would probably just affect regions close to cities," near where reservoirs are concentrated.
Next, the team validated their model by comparing changes in land heights across South Africa to existing models of water storage and loss. They found that the GPS-based results agreed well with predictions of water loss based on satellite measurements and climate data. While the new study doesn't rule out potential contributions from the mantle plume beneath South Africa, the strong correlations with existing models of water storage suggest that water loss is the main driving force behind the uplift.
This suggests that the uplift might not be permanent. With enough precipitation and water returning to reservoirs, the land could start to sink again, Karegar said.
RELATED STORIES
—Earth from space: Golden river of toxic waste spills out from deadly mining disaster in South Africa
—Africa is being torn apart by a 'superplume' of hot rock from deep within Earth, study suggests
—Severe drought helped bring about 'barbarian' invasion of Roman Britain, study finds
But teasing out how long it might take for South Africa to rise or sink again will likely require more data, said Bill Hammond, a geodesist at the University of Nevada Reno who was not involved in the study. "We often don't know how long our current measurements are applicable for," he told Live Science. With just 30 years of GPS data from which to draw trends, many of which South Africa spent in drought conditions, it could be difficult to determine exactly how much of the uplift is due to drought versus the mantle plume, or how long it might take for the land to subside again after the drought's end, he added.
In the meantime, using GPS measurements as a tool for monitoring drought conditions "is a major emerging approach," Karegar said. While South Africa's existing GPS stations are fairly spread out, stations in other parts of the world are spaced much more closely. Where these networks are established, they could help with water management, Karegar said.
Hashtags
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
News24
18 hours ago
- News24
Small win for activists, but SA's HIV projects won't be reopened
The $400 million that the United States Congress removed from a list of programmes from which the Trump administration wants to cut funds, doesn't cancel the cuts to global HIV and TB programmes made in February. HIV projects that have closed in South Africa, which were formerly funded by the US government, won't restart as a result of this decision. The 'limited Pepfar waiver' that President Donald Trump announced in February remains in place. The $400 million that the United States (US) Congress removed from a list of programmes from which the Trump administration will now take back previously approved but unspent funds doesn't mean that the cuts to global HIV and TB programmes in February, including those in South Africa, are now reversed. HIV projects that have closed in South Africa, which were formerly funded by the US government, won't restart as a result of this decision. In fact, quite the opposite. The 'limited Pepfar (President's Emergency Plan for Aids Relief) waiver' that US President Donald Trump announced in February remains in place. That means no HIV-prevention activities, unless they intend to stop pregnant and breastfeeding women from infecting their babies, can be paid for with US government money, and projects that make it easier for teen girls and young women in Africa, trans people, sex workers, injecting drug users and gay and bisexual men - groups of people that have a higher chance of getting HIV than the general population - cannot be funded. READ | 'Systemic shock': SA's HIV viral load testing fell 21% in wake of Pepfar cuts - UNAIDS Without a proper explanation for it, the $400 million seems to be a random amount that Trump's administration picked to take back from Pepfar, a US government programme which funds Aids projects in poorer countries with high HIV infection rates, such as South Africa. The amount is about 8.5% of Pepfar's $4.725-billion budget for this financial year and was part of a larger $9.4-billion 'rescissions package' - that has now been reduced to $9 billion and passed as the HR4 Rescissions Act of 2025. Rescissions happen when the presidential administration wants to cancel funding that was approved by Congress and use it for something else. What the decision to remove the $400 million from the package does, however, mean is that activism could finally be starting to pay off. Activists have had hundreds of meetings with US senators and Congress committee chairs. There have been 'Save Pepfar' social media campaigns, and plenty of media coverage about the devastating consequences of the funding cuts. READ | Motsoaledi urges unity, assures HIV/Aids programme stability amid US Pepfar funding pullout Tens of modelling studies have also projected what could happen if the lost funds are not replaced. Opposition from within Trump's Republican Party against nonevidence-based cuts to a programme that has, for two decades, been supported by both the Democrats and Republicans and has saved over 25 million lives, is now at last emerging. 'It's a small win within the bigger context, but nonetheless, a huge win for advocacy, and a reminder that activism is powerful and alive, and making an impact,' Jirair Ratevosian, a former head of staff at Pepfar and fellow at Duke University's Global Health Institute, told Bhekisisa at last week's Conference on HIV Science in Kigali. Around $8 billion of the money was for foreign aid and development programmes, including global health, and just over $1 billion for public broadcast stations that the Trump administration has accused of being biased because they're too liberal. Marko Milivojevic/Pixnio via Bhekisisa But the Rescissions Act is, in itself, bad news. 'It opens the floodgates for the Trump administration to say: 'We don't want this or that in the budget that Congress approved,' says Mitchell Warren, the head of international advocacy organisation, Avac. 'It's trying to take the congressional power of the purse and put it in the executive branch to usurp the role of Congress in deciding how much money - and on what to spend it.' So how did this all happen, and does it hold any good in the long term for South Africa? We break it down. 1. How did we get here? In the US, Congress - which consists of the Senate and the House of Representatives - decides how much government money goes to who, just like Parliament does in South Africa. Both the Senate and the House have to pass budgets. But, as analysts at the Centre for Budget and Policy Priorities in Washington, DC point out, Trump wants more control over how his administration's money is spent. In March, he signed the 2025 budget that Congress approved into law. Three months later, in June, he decided he wanted to change some of that and submitted a $9.4-billion rescission request, which the House of Representatives (it has five more Republican than Democrat members) passed on 12 June. When it was the Senate's turn to vote on this, some Republican senators weren't happy with the $400-million Pepfar cut, signalling they wouldn't sign off on the deal unless the Pepfar part was removed. Because there was a danger of them swinging the vote, the Republicans removed the $400 million from the Rescissions Bill and got the House to pass that too. All that's left is for Trump to now sign the Act. 2. What was the $400 million that was removed from the Rescissions Act for? In short, no one really knows, because the Trump administration hasn't said what it was for - or what it plans to do with it. But what we do know is that the US law that governs rescissions, the Impoundment Control Act, says that the president can only request that Congress takes back funding that it previously approved, if the money has not yet been obligated - that means funds hadn't yet been given to a particular recipient, for instance, an HIV project in South Africa. We also know that the $400-million was part of the financial budget for 2025, says Warren, but because the law gives Pepfar permission to spend money over five years, that money doesn't have to be legally spent until 2029. 3. What will the $400 million now be used for? Again, no one knows. We don't even know if it will be used, because over the past few months, the Trump administration's main strategy has 'simply been to illegally impound funds - by announcing a 'funding freeze' or 'programmatic review' with no public notice at all - and force those harmed by the impoundments to pursue relief in court', the Centre on Budget and Policy Priorities explains in an analysis. But we do know what the money can't be used for. Unless the rules of Trump's 'limited waiver' are changed, Pepfar funds can mostly not be spent on any of the evidence-based strategies it paid for before Trump was elected in January. Pepfar used to focus on groups of people and areas where people have the highest chance of getting infected with HIV - that way, the programme got the biggest bang for its buck. In South Africa, for instance, Pepfar worked in the 27 districts with the highest infection rates and groups known as 'key populations' - sex workers, gay and bisexual men, trans people, injecting drug users and African women between the ages of 15 and 24 - that are much more likely to get newly infected with HIV than other South Africans. Now those projects, which studies show stopped many new infections, have been closed down and the Trump administration says it's not prepared to buy HIV prevention medicine for any group other than pregnant and breastfeeding women. 'It used to be all about evidence,' Warren says. 'Now it's all about ideology.' 4. What do scientists and activists want the $400 million to be used for? Ratevosian says this moment should be used to gain Republican support to change the waiver rules, so that Pepfar money can cover more of the populations and services needed for HIV prevention. Lenacapavir, a pricey twice-a-year anti-HIV jab, which scientists believe could help to stop HIV in its tracks if it's rolled out properly, could be used to convince Republican Congress members, says Ratevosian. 'Pepfar has long wanted to get countries to transition to taking more ownership [read: Pay more] for their HIV responses. So now activists are arguing: 'Preventing more new infections with the jab, will make it easier for countries to take ownership because the pandemic will be easier to manage.'' In December, Pepfar said it would join another organisation, the Global Fund for HIV, TB and Malaria to buy enough lenacapavir for two million people over three years. But in July, the Global Fund had to go ahead with the deal by itself, because Pepfar seemed to no longer be on board. Warren says: 'If I were in charge, I would take the $400 million and double the two million people the Global Fund is planning to cover, because that's how you build a market, prevent new infections more quickly and drive the price down.' 5. What will Pepfar look like in future? Trump's funding cuts didn't kill Pepfar - at least not in theory, but it's a shell of its former self. What it will look like, will depend on the size of its next budget (the Trump administration wants to cut it by 40% but, so far, the House hasn't agreed to that, (the Senate still needs to sit on it) and how much support Republicans who believe in Pepfar can gain to have waiver rules changed. But, Warren points out, 'we're not going to get pre-January projects back; we have to build something different. 'This has been the most seismic shift in democracy. We didn't think we lived in an earthquake zone, but January 20 (when Trump retook office) taught us: You need to be prepared for that earthquake and you therefore need a different infrastructure. 'In an earthquake you don't build back the same thing. You build better, something that is more resilient.' Show Comments ()
Fast Company
a day ago
- Fast Company
Taxpayer-funded vaccines meant to aid Africa are at risk of expiring
Hundreds of thousands of doses of mpox vaccine that the United States had promised to send to African nations are in danger of going to waste, dozens of congressional Democrats said in a letter to the U.S. State Department on Wednesday. Forty-eight Democratic members of the House of Representatives, led by Representatives Mark Pocan of Wisconsin and Sara Jacobs of California, signed the letter, saying that the vaccines may expire as they sit in warehouses, wasting the U.S. taxpayer dollars that paid for them. The letter said 800,000 doses of the vaccines are at risk, and that some 220,000 doses could be viable if the State Department begins shipping them immediately. 'This is a moral, strategic, and public health failure in the making,' the letter said. Republican U.S. President Donald Trump has made sharp cuts to foreign aid programs since beginning his second term six months ago, firing thousands of aid agency employees and contractors and throwing global humanitarian operations into chaos. The Republican-controlled Senate and House of Representatives passed legislation this month approving Trump's request for about $8 billion in foreign aid cuts. Trump has said the U.S. pays disproportionately for foreign aid, and he wants other countries to shoulder more of the burden. The World Health Organization first declared the outbreak of mpox in August 2024, when an outbreak of a new form of the disease spread from the badly-hit Democratic Republic of Congo to neighboring countries. Uganda and Burundi also have been significantly affected.
New York Times
a day ago
- New York Times
U.S. Quietly Drafts Plan to End Program That Saved Millions From AIDS
The federal program to combat H.I.V. in developing nations earned a reprieve last week when Congress voted to restore $400 million in funding. Still, officials at the State Department have been mapping out a plan to shut it down in the coming years. Planning documents for the President's Emergency Plan for AIDS Relief, obtained by The New York Times, call for the organization to set a new course that focuses on 'transitioning' countries away from U.S. assistance, some in as little as two years. PEPFAR, as the program is called, would cease to exist as an initiative to provide medicines and services needed to treat and prevent the spread of H.I.V. in low-income countries. It would be replaced by 'bilateral relationships' with low-income countries focused on the detection of outbreaks that could threaten the United States and the creation of new markets for American drugs and technologies, according to the documents. 'With targeted investment, PEPFAR's H.I.V. control capabilities in these countries could be transformed into a platform for rapid detection and outbreak response to protect Americans from disease threats like Ebola,' the plan says. A State Department spokeswoman said the document had not been finalized. 'The referenced document is not reflective of the State Department's policy on PEPFAR and was never cleared by Department leadership,' she said. Want all of The Times? Subscribe.
