A major study has shown that high temperatures can harm global moods. Researchers analysed more than one billion social media posts. When temperatures crossed 35°C, negative expressions increased, especially in lower-income countries. Wealthier nations also saw changes but at a much smaller scale.
The analysis, led by MIT with international collaborators, compared online sentiment scores with local daily weather data. Results revealed low-income regions suffered three times the emotional effect seen in richer ones. Heat was not only uncomfortable but also strongly linked to declining positivity.
Behaviour Under Rising Heat
Past findings support this connection between heat and behaviour. Drivers honk more on hot days. Journalists adopt harsher language during heatwaves. Violence and crime often rise when temperatures climb. In Greece, many murders occurred on days warmer than 25°C. Historical studies show uprisings frequently taking place during peak summer months. Hotter weather has also been associated with higher suicide risks.
Scientists suggest temperature may alter brain chemicals or raise hormone levels that fuel aggression. Still, they note that heat interacts with many social and cultural pressures to shape outcomes.
The Future of Mood in a Hotter World
Climate projections indicate global sentiment could decline by about 2.3% this century because of increasing heat. Vulnerable groups such as children and the elderly, often missing from social media, may experience even heavier impacts.
Experts highlight that while infrastructure protects against physical dangers, societies must also prepare for emotional consequences. Building resilience against heat’s psychological effects will be central to adaptation.
