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New research shows extreme heat affects our emotions, with moods turning more negative when temperatures rise above 35°C. Scientists warn climate change could take a growing toll on global mental well-being.

Is Hot Weather Putting You in a Bad Mood? Science Suggests It Might Be

If sweltering summer days have you feeling irritable, impatient, or just plain cranky, you're not imagining things. According to new research, extreme heat doesn't only make us sweat -- it also makes us sour. Scientists have found that when temperatures rise above 35°C, our moods collectively take a nosedive, with the effects felt most sharply in lower-income countries.

The study, published in the journal One Earth, analysed over a billion social media posts from around the world to better understand how climate change is shaping human emotions. The results provide some of the strongest evidence yet that our warming planet could be making us unhappier.

A Global Study of Heat and Human Emotions

Researchers from MIT, the Chinese Academy of Sciences, and other institutions examined 1.2 billion posts from platforms including X (formerly Twitter) and Weibo across 157 countries. Each post was given a sentiment rating ranging from 0.0 for very negative to 1.0 for very positive.

They then matched the content to weather data at 2,988 global locations over the span of a year. What they found was striking:

This disparity highlights how much socioeconomic factors shape people's ability to cope with heat. For wealthier nations, air conditioning, better infrastructure, and access to healthcare cushion the effects. For poorer communities, extreme heat often compounds existing challenges, amplifying stress and frustration.

"Social media provides us with an unprecedented window into human emotions across cultures and continents," explained study co-author Jianghao Wang from the Chinese Academy of Sciences. "This approach allows us to measure emotional impacts of climate change at a scale that traditional surveys cannot achieve, giving us real-time insights into how temperature affects human sentiment worldwide."

Why Does Heat Make Us Angry?

The connection between temperature and mood isn't a new discovery. Psychologists and sociologists have studied this phenomenon for decades, with evidence suggesting that hot weather heightens aggression, irritability, and even violence.

For example:

The effects aren't limited to outward aggression. Heat may also drive people to turn their frustrations inward. A 2018 study linked hotter days to an increased risk of suicide, showing how the psychological impact of temperature extremes can be both subtle and severe.

The Biology Behind Heat and Mood

But why exactly does heat affect our emotions? Several scientific theories attempt to explain the connection:

It's important to note that most of these studies show correlation, not direct causation. While there's a strong link between heat and negative moods, many other factors -- like infrastructure, cultural expectations, or existing mental health challenges -- play a role in shaping outcomes.

An Unequal Burden

The latest study emphasises that climate-driven mood changes are not felt equally around the world. The emotional toll in lower-income countries was three times higher than in wealthier ones.

This gap underscores the broader reality of climate change: those least responsible for global warming are often those most affected by its impacts. Lack of access to cooling systems, healthcare, and social safety nets makes extreme heat not just uncomfortable but also destabilising to communities.

The researchers argue that these findings should inform future climate adaptation strategies. Recognising that heat doesn't just impact physical health but also emotional well-being could help governments and institutions design better policies, from mental health support during heat waves to infrastructure investments in vulnerable regions.

What the Future Holds

Looking ahead, the researchers used global climate models to predict how rising temperatures might affect our collective mood by the end of the century. Even assuming that societies adapt gradually to higher temperatures, they projected a 2.3% decline in global sentiment by 2100 -- a measurable dip in positivity driven primarily by heat.

"It's clear now, with our present study adding to findings from prior studies, that weather alters sentiment on a global scale," said co-author Nick Obradovich, from MIT's Sustainable Urbanisation Lab.

While a 2.3% decline may seem small, applied globally it represents a profound shift in emotional well-being, potentially affecting everything from interpersonal relationships to political stability.

Final Thought

Heatwaves are no longer just a test of physical endurance -- they're a test of our emotional resilience too. As global temperatures climb, how we adapt to the psychological strain will be just as crucial as how we adapt to the physical risks. Recognising the mental toll of extreme heat is the first step toward building healthier, more resilient communities in a warming world.

Conclusion

The science is becoming increasingly clear: hotter weather doesn't just threaten our environment, it also threatens our moods. From road rage to rising crime rates, the emotional toll of heat is being felt in ways both personal and societal. And as climate change continues to push temperatures higher, these impacts are likely to grow.

For individuals, the findings are a reminder of the importance of adaptation -- whether through cooling strategies, better infrastructure, or mental health support during heat waves. For policymakers, it underscores the urgent need to prepare not just for physical consequences of climate change, but for its psychological ones as well.

As the planet warms, the forecast for our emotional climate may be just as important as the one for our weather.

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Hot Weather, Bad Moods: How Rising Temperatures Are Affecting Our Emotions