Heat raises irritability, not violence

A cross‑cultural experimental study (PNAS Nexus) used behavioral games (the 'Envy Game' with cake) across the U.S., Mexico, Colombia, Kenya and India and found higher temperatures increased irritability but did not reduce prosocial behaviour or increase punitive choices. The study suggests macro correlations between heat and conflict may arise from structural factors (resources, adaptation capacity) rather than a simple physiological path from heat to interpersonal aggression. — This reframes climate‑violence debates: policymakers should focus on resource and adaptation gaps, not assume heat directly makes people more violent.