Climate change is making heat stress one of the most widespread welfare problems in animal agriculture. Understanding the scale and solutions is increasingly urgent.
Heat stress is a form of suffering — the physiological state involves discomfort, elevated stress hormones, and progressive organ failure in severe cases. As global temperatures rise, the proportion of livestock exposed to heat stress above welfare-relevant thresholds is increasing. The welfare burden falls heaviest on intensively housed animals without access to shade, water, or adequate ventilation. Factory farming systems built for temperate climates face increasing welfare challenges in a warming world. The economic costs of heat stress — reduced production, increased mortality — align with the welfare case for mitigation, but the investment required is often greater than producers make voluntarily.