A drumbeat of climate-fueled heatwaves, compounded by water management practices, will likely kill nearly all juvenile chinook salmon in the Sacramento River, California wildlife officials warn. “It’s an extreme set of cascading climate events pushing us into this crisis situation,” California Dept. of Fish and Wildlife spokesperson Jordan Traverso told reporters. Salmon need river water at or below 56°F to fully develop (which, in a human context, is so dangerously cold it can inhibit your ability to control your breathing).

Low river levels caused by drought mean the water heats and evaporates faster, which lowers, and thus further warms the water in a vicious cycle. The salmon die-offs have increased due to diversions from the Shasta Reservoir, which was formed by damming the Sacramento River in the 1940s, to the agriculture industry across the Central Valley, itself parched by the climate-fueled megadrought. (CNN, Sacramento Bee $, Gizmodo, Newsweek; Cold water effects: Weather.com, ColdWaterSafety.org, UseAKayak.org; Climate Signals background: Extreme heat and heatwaves, Drought)