Aquifers, rain and tornadoes push past familiar baselines
Long groundwater losses in Brazil’s major basins, a record day of rain in Chiba and Illinois’s exceptional tornado count are challenging familiar measures of the water cycle and severe weather.
Science··Morning
Years of aquifer loss under Brazil’s basins
Augusto Getirana of NASA Goddard and colleagues trained models on 398 monitoring wells, gravity satellite data and geology to reconstruct monthly groundwater from 2002 to 2023. Severe, persistent losses cover about 23 per cent of Brazil’s land area. The reconstruction runs at a resolution of roughly 10 kilometre and covers portions of the São Francisco, Paraná, Southeast Atlantic and East Atlantic basins totalling 1.97 million square kilometres. Getirana says climate creates the underlying deficit while extraction and land-use change probably amplify it, and the study itself does not attribute losses to specific pressures. Javier Tomasella of Brazil’s National Institute for Space Research, who was not involved, points to droughts that last longer and bite harder. Groundwater supplies 55 per cent of the country’s water and hydropower 60 per cent of its electricity, which is how a groundwater trend reaches the power grid. The study appeared in Science Advances. The reconstruction combines satellite and geological information where the well network is sparse to produce a national-scale picture.[1]
367 millimetres in a day over Chiba
Rainfall in Chiba Prefecture east of Tokyo reached 367 millimetres in a day, the area’s heaviest daily total since at least 1976. Of that total, 348 millimetres fell within 12 hours, about three times the region’s usual rainfall for the whole of August. At least 8 people died as the storm stranded travellers at Narita and cut power to tens of thousands of homes. The Japan Meteorological Agency issued its highest-level heavy rain warning for the region for the first time. Officials attribute the event to humid air moving north from southern Japan and meeting a cold mass some 6,000 metre above Honshu, leaving the atmosphere unstable. Kai Chen of the Yale Center on Climate Change and Health says warmer air holds more moisture, which raises the ceiling on downpours of this kind, and that extreme rainfall carries health costs well past the immediate deaths. Issuing that warning for the first time shows the event also crossed a threshold in the region’s warning history.[2]
204 Illinois tornadoes and a detection caveat
Six tornadoes crossed the Chicago area during a derecho on Tuesday, taking Illinois’s 2026 count to 204. Only Texas, with roughly five times the land area, has topped 200 twisters in a year, reaching 244 in 2015. Illinois’s second-busiest year was 2024 with 142 twisters, and the US total stands at 1,292 so far this year. Tornadoes form where warm, moist air meets cooler, drier air in a strong thunderstorm; the atmosphere over Illinois has grown warmer and more humid with climate warming, and this spring that air met a jet stream running through the Midwest. Brett Borchardt of the National Weather Service in Chicago adds that better radar and reporting may mean the count now reflects a more realistic number than earlier decades managed, while still calling the year remarkably busy. Multi-year groundwater decline, Chiba’s daily rainfall extreme and Illinois’s tornado pace show familiar baselines for the water cycle and severe weather being pressed at once. Together the three lines show that water and severe-weather metrics can leave familiar ranges and that each still needs to be read with its own observational uncertainty.[3], [1], [2]
