Scientists studying more than a billion social media posts across 157 countries discovered that negative emotions rise sharply once temperatures exceed 35°C. The effect was far greater in low‑income regions, with negativity increasing three times more than in high‑income areas. The research, led by MIT and international partners, linked daily sentiment scores from platforms like X and Weibo to local weather conditions.
Behavioural Patterns in Hot Weather
Past evidence shows heat changes behaviour in significant ways. Drivers honk more during hot spells, journalists use harsher wording, and crime rates tend to increase. Studies from Greece found that murders were more common on very warm days. Historical records suggest that uprisings and conflicts erupted more frequently in summer months. Hot weather has also been associated with higher suicide rates. Researchers suggest that changes in neurotransmitters such as serotonin and shifts in hormones related to aggression may underlie this response, alongside social and economic pressures.
Outlook for the Future
Climate projections indicate that global positivity could decrease by around 2.3 percent by 2100 if warming continues. Because children and elderly people are underrepresented on social media, the true emotional toll may be even greater. Experts argue that societies must prepare not only by protecting infrastructure and physical health but also by building resilience against the psychological strains of rising temperatures.
