August M
From Louisiana to The Gambia, a quiet shift is reshaping coastlines and livelihoods. Freshwater once drawn from taps and rivers is turning brackish, threatening drinking supplies and food production.
Scientists warn that saltwater intrusion, driven by climate change and human activity, is accelerating worldwide.
Saltwater intrusion occurs when seawater moves inland into freshwater aquifers. According to the BBC, all continents except Antarctica are projected to experience at least 1km of inland saltwater intrusion in coastal areas by 2050.
“Saltwater intrusion is a perfect example of a slow-onset climate crisis,” Robert Young, a professor of coastal geology at Western Carolina University, told the BBC. “We prepare for the wrong disasters, [but slow-onset climate effects] are the ones that can really impact the future of coastal communities, especially in the developing world.”
Farms under threat
In The Gambia, where rice farming sustains thousands, the impact is already visible. Nurse Senneh, a farmer from Sankandi village, says creeping saltwater has devastated her once-productive fields.
“I had to leave because of the saltwater intrusion,” she told the BBC. “Now, the entire rice field affected is left uncultivated.”
According to a 2024 assessment cited by the BBC, The Gambia recorded a 42% reduction in rice-growing areas and a 26% drop in production between 2009 and 2023 due to saltwater intrusion. The Gambia River now carries saline water as far as 250km inland.
Climate change is a key driver, says Sidat Yaffa of the University of The Gambia, pointing to rising sea levels and a 30% decline in annual rainfall since the 1970s.
A global pattern
The US is also experiencing the effects. In south Florida, the Biscayne Aquifer faces growing salinity pressure, while Louisiana residents have reported salty tap water, according to the BBC and previous reporting by The Guardian.
Holly Michael, a coastal hydrogeologist at the University of Delaware, explained that the balance between sea level and inland water levels determines how far saltwater advances. Climate change and groundwater over-extraction are tipping that balance.
Studies cited by the BBC show drinking saline water can increase risks of high blood pressure and pregnancy complications.
Holding back the tide
Countries are experimenting with solutions. Florida has installed tide gates to limit saltwater flow, while Vietnam has built sluice gates to shield the Mekong Delta. Wastewater injection projects in the US, China and the Netherlands aim to replenish freshwater reserves.
But experts caution there is no universal fix. “There are no silver bullets, and what works in one place may not work in another,” Lizzie Yarina of Northeastern University told the BBC.
For farmers like Senneh, time is running out. “If not, [saltwater intrusion] will become worse and life will be unbearable for us,” she said.
Sources: BBC, The Guardian, 2024 National Environment Agency impact assessment
