New research shows that extreme heat can darken our moods. Scientists studied over a billion social media posts worldwide. They tracked emotional tone in relation to daily temperatures from more than 150 countries. When the thermometer climbed above 35°C, negative moods surged, particularly in low-income regions.
The investigation included 1.2 billion posts from X and Weibo across 157 countries. Each message received a sentiment score between negative and positive. Hotter conditions consistently reduced positivity, with stronger effects in poorer areas than in wealthier ones.
Anger, Violence, and Heat
Links between temperature and aggressive behaviour stretch back decades. Drivers show more road rage during heatwaves, especially without cooling. Journalistic language also shifts negatively in high temperatures.
Crime statistics reflect similar patterns. In Greece, one-third of murders over a decade occurred on days above 25°C. Global historical events reveal more uprisings during hot summer months. Studies even associate hotter days with increased suicide risk.
Scientists suggest several possible mechanisms. Heat may disturb brain chemistry, lowering stabilizing serotonin or altering hormone levels that drive aggression. Still, heat’s effect may combine with broader social conditions.
Future Outlook
Climate models predict that by 2100, global sentiment could decline by 2.3% because of rising temperatures. Researchers stress the need to understand emotional resilience as much as physical adaptation. Vulnerable groups absent from social media make the real burden potentially higher.
As heatwaves grow more frequent, preparing for emotional consequences may become as vital as protecting against physical effects.
