Droughts

Brazil is entering a hidden water crisis as deforestation, fires, agribusiness expansion and mining weaken the Amazon–Cerrado hydrological system that underpins rainfall, river flows and groundwater across much of South America and beyond. Despite holding about 12 percent of the world’s freshwater, ecosystem degradation is making rainfall more erratic, rivers less reliable, fish stocks and water quality decline, and communities and cities like São Paulo increasingly vulnerable to droughts, floods and “water bankruptcy.” Scientists argue that only rapid measures such as zero deforestation by 2027, reducing cattle herds and monocultures, restoring forests and reforming water governance can stabilise Brazil’s water future and the global food and climate systems that depend on it.

Extreme droughts, floods and heatwaves are rapidly transforming rivers worldwide, pushing ecosystems beyond their limits, triggering biodiversity loss and long‑lasting shifts in how river systems function. Because rivers are highly connected and already stressed by pollution, land-use change and water withdrawals, extreme and compound events (like drought plus heatwave, or wildfire plus flood) can cause cascading, unpredictable impacts far downstream, including fish kills and invasions by non-native species. The authors argue that protecting rivers now requires a shift from local, reactive measures to catchment‑scale, resilience‑focused strategies that combine nature‑based solutions, habitat restoration, connectivity, and engineered or natural refuges to prepare for a more extreme climatic future.