1. [para. 1][para. 2][para. 3][para. 4] In May 2024, extreme heat reached 45°C in Chiapas, Mexico. Howler monkeys died from dehydration and heatstroke, falling from the trees. Rescuers saved some, but at least 83 died. [para. 5] This anecdote illustrates global warming; the years 2023-2025 were the hottest on record.2. [para. 6][para. 7] The heat disrupted human society, causing heatstroke in Washington D.C. and over 1,000 excess deaths in France, which closed a stage of the Tour de France. [para. 8] As Li Zhongqiu noted, humans can use air conditioning, but animals cannot, making wildlife far more vulnerable.3. [para. 9][para. 10] A special issue of *Nature Ecology & Evolution* projects 74% of over 30,000 species' habitats will face heatwaves. [para. 12][para. 13] Behavior changes immediately: dog bites rise 4% on hot days and chamois attacks increase 120%. [para. 14][para. 15] While aggression peaks below 35°C, animals become too drained above it. [para. 16][para. 17] Pied babblers grow “numb” to predators in extreme heat, diverting energy to cooling, a cost that accumulates in the population.4. [para. 19][para. 20] A critical hidden cost is reproductive damage. Sea urchins fail to mature eggs at just 20°C. [para. 21] Mediterranean coral sterility jumped from 11% to 58%. [para. 22][para. 23] Paul Jacobs found brief heatwaves crushed fertility in striped mice. “Survival alone doesn't capture the full picture.” [para. 24] This toll on “load-bearing” mammals ripples through ecosystems. [para. 25] Sea turtles in Florida are hatching nearly all females, preventing sustainability.5. [para. 27][para. 28][para. 29] The worst effects are delayed. The “Blob” marine heatwave caused a 56% decline in Alaskan humpback whales from collapsed food and calving. [para. 30][para. 31] Across species, reduced lactation causes slower growth, and heat-exposed chicks have permanent learning deficits, mirrored in human children. [para. 32][para. 33] Populations look stable while their renewal fails silently. The most overlooked question is what happens after the heatwave.AI generated, for reference only