Scientists analysed over a billion social media posts to study how extreme heat impacts emotions worldwide. Research led by MIT and global institutions mapped people’s moods on hot days using posts from over 150 countries. The study, published in One Earth, revealed that moods worsen when temperatures rise above 35°C, especially in lower-income regions.
Researchers examined 1.2 billion posts from X and Weibo across 157 countries. Each post received a sentiment score and was linked to local weather. When heat exceeded 35°C, negative posts increased by 25% in lower-income nations and by 8% in wealthier ones.
Social media provided a new large-scale window into human emotions under climate stress. The authors stressed that climate models must include emotional impacts of future heatwaves.
Heat, Anger, and Behaviour
Links between high temperatures and irritability are long established. Drivers honk more in hotter weather, especially without air conditioning. Journalists even use more negative language in heat, as one Beijing Olympics study showed.
Evidence also connects heat with crime and violence. In Greece, over 30% of recorded murders between 1995 and 2004 occurred on hot days above 25°C. Historical research linked most global uprisings from 1791 to 1880 to summer months. Other studies reveal that suicides increase during hot weather.
Experts propose several explanations. High heat may alter brain chemistry, lowering serotonin levels and raising aggression through increased testosterone. Still, most studies show correlation, not direct causation, meaning other factors may influence outcomes.
Looking Ahead
Using climate models, researchers estimate global sentiment could decline by 2.3% by 2100 due to rising heat. They emphasize that resilience against emotional impacts of climate change is crucial for societal adaptation. Yet the study notes gaps: children, elderly, and others most vulnerable to heat are underrepresented online, suggesting the true impact may be greater.
Understanding heat’s psychological toll is increasingly important as the planet warms. Physical adaptation is vital, but preparing for emotional consequences may prove equally essential.
