How Extreme Heat Affects Human Emotion: A Global Study

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As global temperatures continue rising and our collective mood potentially shifts toward persistent negativity, what happens to us? How does chronic heat-induced irritability affect social cohesion? Political stability? Our capacity for the cooperation and empathy we'll desperately need to address climate change itself?

There's a dark feedback loop lurking here: climate change makes us more emotionally negative, which could make us less capable of the sustained collaborative effort needed to address climate change. Heat doesn't just make us uncomfortable—it potentially undermines our ability to respond effectively to the crisis creating that heat.

References: Extreme Heat Makes People More Negative

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Transcript

Speaker 1: 0:25

This is Heliox, where evidence meets empathy. Independent, moderated, timely, deep, gentle, clinical, global, and community conversations about things that matter. Breathe easy. We go deep and lightly surface the big ideas. Have you ever had one of those days where the heat just feels, well, personal, like a really sweltering, muggy afternoon doesn't just make you uncomfortable, but it actively drains your energy, frays your nerves, leaves you feeling inexplicably irritable, maybe even a bit down, even when nothing specific has gone wrong. For years, we've probably all just dismissed that as, you know, a minor thing, a personal reaction.

Speaker 2: 1:13

Right, it's part of a hot day.

Speaker 1: 1:14

Exactly. But what if that feeling wasn't just your personal experience or purely anecdotal? What if it was actually a quantifiable global thing? Today, we're peeling back the layers on a truly groundbreaking global study. It reveals just how profoundly extreme heat isn't just physically uncomfortable, but a measurable force impacting our collective emotional well-being on a planetary scale.

Speaker 2: 1:39

Yeah, this isn't just about being sweaty. It's deeper than that.

Speaker 1: 1:42

Much deeper. It suggests a fundamental shift in our global mood, really. We're drawing our insights today from a really fascinating article by Neuroscience News. It summarizes a major study. And this research, it was published in the journal One Earth, spearheaded by a pretty impressive international team, MIT, the Chinese Academy of Sciences, other big institutions.

Speaker 2: 2:04

Top researchers.

Speaker 1: 2:05

It gives us this unprecedented, truly global look at this vital and frankly surprising phenomenon.

Speaker 2: 2:12

And what's really fascinating here, I think, is how this research unveils this new critical dimension of climate change. It's direct day-to-day impact on our emotions, our human emotions.

Speaker 1: 2:23

Right. It goes beyond the physical, the economic.

Speaker 2: 2:26

Exactly. To something deeply personal for all of us. So for you listening, our mission today is to explore the sheer, well, mind-boggling scale of this analysis and to uncover the stark and often surprising disparities in its effects across different populations. and crucially, understand what it might project for our emotional future as the world keeps warming.

Speaker 1: 2:46

A global mood swing driven by heat.

Speaker 2: 2:49

You could say that. It's a profound wake-up call, really.

Speaker 1: 2:51

Okay, let's unpack this then. The core finding when you boil it down is pretty striking. Very hot days are unequivocally associated with more negative moods. But I want to stress, this isn't simply people tweeting, uh, it's hot.

Speaker 2: 3:08

No, it's more nuanced.

Speaker 1: 3:09

Right. The study went way beyond just subjective complaints. It looked at expressed sentiments, the actual emotions, the subtle shifts in tone and feeling people put out there online.

Speaker 2: 3:19

It's like a quantitative measure of this subtle emotional erosion that we haven't really measured before on this scale.

Speaker 1: 3:25

Revealing a hidden psychological cost of climate change.

Speaker 2: 3:29

Precisely. And if we step back and think about the bigger picture, the sheer ambition, the scope of this study is what makes it so compelling, so powerful. I mean, the researchers didn't just do a few surveys.

Speaker 3: 3:38

Yeah.

Speaker 2: 3:38

To get this global mood, they examined an astounding 1.2 billion social media posts.

Speaker 1: 3:45

1.2 billion. It's hard to even wrap your head around that number.

Speaker 2: 3:48

It really is. An almost incomprehensible amount of data of human expression. And they focused on posts from two huge platforms, Twitter and Weibo. These act like these vast real-time reservoirs of public feeling.

Speaker 1: 4:02

Okay.

Speaker 2: 4:03

And the coverage wasn't just volume, it was breadth. All posts from 2019 covering 157 countries, 65 different languages. So not just a snapshot, you know, more like a deeply textured global tapestry of human emotion.

Speaker 1: 4:17

The scale is just incredible. So with that data set, how on earth did they even begin to sift through it to understand the sentiment? It sounds like finding needles in a billion post haystack.

Speaker 2: 4:26

Well, it's pretty ingenious, actually. Leveraging cutting-edge AI, they used a natural language processing technique called BERT, short for bidirectional encoder representations from transformers.

Speaker 1: 4:35

Bert Talley, easier to remember.

Speaker 2: 4:36

Definitely. And the key thing is, this isn't just counting happy or sad words. Bert understands context nuance.

Speaker 1: 4:42

Like sarcasm. Or subtle shifts in mood.

Speaker 2: 4:46

Exactly. Much like a human can. Yeah. So it assigned each post a sentiment rating. 0.0 for very negative, up to 1.0 for very positive. Gaging genuine sentiment with, well, pretty impressive accuracy.

Speaker 1: 4:59

Okay, so they have sentiment scores for billions of posts. What then? They didn't just leave it there, I assume?

Speaker 2: 5:05

No, they aggregated them geographically. Basically boiled it down to sentiment averages for nearly 3,000 specific locations worldwide. Around 2,988, I think. Got it. Then came the critical step, correlating these sentiment scores with local weather data for each specific area.

Speaker 1: 5:22

Ah, connecting the mood to the temperature. Precisely.

Speaker 2: 5:25

This whole sophisticated method let them draw a remarkably direct, robust line between rising temperatures and the mood people expressed online. in real time, all across the globe.

Speaker 1: 5:34

Which raises a question, doesn't it? Why social media? Aren't traditional surveys the, you know, the gold standard?

Speaker 2: 5:40

That's a fair question. And the researchers have a compelling answer. One of the co-authors, Jiang Go Wang, basically said social media gives this unprecedented window into emotions across cultures, continents. He said this approach lets them measure emotional impacts of climate change at a scale surveys just cannot achieve.

Speaker 1: 6:01

Real-time insights.

Speaker 2: 6:03

Yeah. Worldwide. Exactly. Traditional surveys are slow, expensive, limited. This method effectively turned the world into this huge, responsive sentiment gauge.

Speaker 1: 6:13

A global thermometer for our mood.

Speaker 2: 6:15

You got it. Insights that were just unreachable before this kind of tech.

Speaker 1: 6:18

It's an incredible application of technology. And there's a nuance here that really stood out to me. It's not simply heat equals bad mood, is it?

Speaker 2: 6:26

No, it's more complex than that.

Speaker 1: 6:27

The study found that while temperatures above 95 Fahrenheit, that's 35 Celsius, definitely led to negative impacts globally. Moderate warming, just a little bit warmer, could actually improve sentiment in cooler regions.

Speaker 2: 6:39

Right. Think about that first warm, sunny day after a long winter. It often lifts spirits, doesn't it?

Speaker 1: 6:45

Totally. So it's not just any heat. It's the extreme heat, the sustained, sweltering stuff that really shifts things towards negativity.

Speaker 2: 6:53

A little warmth is welcome. Too much is clearly detrimental to our mood.

Speaker 1: 6:58

Okay, now here's where it gets really interesting, maybe a bit sobering too. The study found a pretty stark difference in impact based on income levels.

Speaker 2: 7:07

Yeah, this is crucial.

Speaker 1: 7:08

This isn't hitting everyone equally. It reveals this layer of climate inequality that's, well, deeply emotional.

Speaker 2: 7:15

Absolutely. The core finding is clear. Above that 95 degrees F, 35 degrees C mark, expressed sentiments got demonstrably more negative consistently. But, and this is the key part, the effect wasn't uniform. Not at all. The researchers used the World Bank's income cutoff, about 13,845 GNI per capita, to distinguish between lower and higher income countries, a concrete metric.

Speaker 1: 7:38

OK, so what were the numbers?

Speaker 2: 7:39

They are stark. In lower income countries, sentiment became about 25 percent more negative above that heat threshold. 25 percent. Now compare that. In higher income countries, same extreme heat. Sentiment dropped about 8 percent more negative.

Speaker 1: 7:51

8 percent versus 25 percent.

Speaker 2: 7:53

Exactly. The significance is profound. The effect is three times stronger in lower income countries.

Speaker 1: 8:00

Three times.

Speaker 2: 8:01

It dramatically shifts how we should think about climate inequality. The emotional burden isn't just uneven. It's overwhelmingly heavier for those with fewer resources.

Speaker 1: 8:11

Turning climate change into this deeply personal emotional crisis for the most vulnerable.

Speaker 2: 8:17

That's a good way to put it.

Speaker 1: 8:18

And the researchers themselves were very clear about this, right? Yuchen Fan, another co-author, said explicitly, thanks to the global coverage, we find people in low- and middle-income countries experience sentiment declines from extreme heat that are three times greater. This underscores the importance of incorporating adaptation into future climate impact projections.

Speaker 2: 8:39

The direct call to action, isn't it? integrate this emotional dimension into our climate strategies urgently.

Speaker 1: 8:45

If we broaden the view, this isn't just economics like GDP hits or just physical health like heat stroke.

Speaker 2: 8:50

No, it's shaping the actual lived emotional experiences of people worldwide, day to day.

Speaker 1: 8:55

Their interactions, their well-being.

Speaker 2: 8:57

And critically, disproportionately burdening the world's poorest. It shows how climate change isn't abstract. It's about this pervasive, unequal emotional toll.

Speaker 1: 9:08

A hidden layer of injustice we're only now starting to quantify properly.

Speaker 2: 9:12

Yeah.

Speaker 1: 9:13

So given these findings from 2019, which are already pretty unsettling, what does this mean long term? They looked ahead, didn't they? Made projections.

Speaker 2: 9:22

They did. They used long term global climate models to project these emotional impacts out to 2100. And importantly, they factored in some expected adaptation, you know, maybe better AC changes in work patterns, things like that.

Speaker 1: 9:34

So even with adaptation.

Speaker 2: 9:35

Even with that, the projection is still significant. There's specific calculation. Extreme heat alone could worsen global emotional well-being by about 2.3% by 2100.

Speaker 1: 9:45

2.3% globally.

Speaker 2: 9:46

Now, 2.3% might sound small in isolation.

Speaker 1: 9:49

But across billions of people over decades.

Speaker 2: 9:52

Exactly. It indicates these lasting psychological costs accumulating over generations. Think about what even a subtle, persistent erosion of well-being means. More stress, less patience, maybe less social cohesion.

Speaker 1: 10:04

Impacts on productivity, public health.

Speaker 2: 10:06

Potentially. It suggests a future where our collective baseline mood is just that little bit more negative, more irritable, just because of the heat.

Speaker 1: 10:15

That's a powerful thought. Now, we should always mention limitations, and the researchers acknowledged this. Social media users aren't a perfect mirror of the whole population, right? Very young kids, the elderly, they use it less.

Speaker 2: 10:28

That's true. They are underrepresented in this kind of data. However, and this makes it even more concerning, as the researchers point out, the very young and the elderly are actually particularly vulnerable to heat shocks, physically and emotionally.

Speaker 1: 10:42

Ah, so the real impact could be even worse.

Speaker 2: 10:45

It raises that important question definitely. What if the true emotional toll is larger than what this study, using this method, could capture? If these highly vulnerable groups were fully represented, the negative sentiment might be even more pronounced.

Speaker 1: 10:59

So the study might even be a conservative estimate. That really underlines the urgency.

Speaker 2: 11:04

It does. And Nick Obradovich, another co-author, summed it up well. He said, basically, it's clear now whether alters sentiment globally. And as climates change, helping people become more resilient to these emotional shocks. That's a vital part of societal adaptation.

Speaker 1: 11:21

Expanding our definition of adaptation beyond just infrastructure.

Speaker 2: 11:24

Exactly. It's about building emotional resilience, too, in individuals, in communities.

Speaker 1: 11:29

Okay, so let's recap this deep dive for everyone listening. Groundbreaking research shows extreme heat directly hits our emotions, leading to measurably more negative feelings globally. Critically, this impact hits lower income countries three times harder, a huge disparity. And looking ahead, even with some adaptation, extreme heat alone is projected to worsen our collective global mood by around 2.3% by 2100.

Speaker 2: 11:52

And connecting this to the bigger picture, this research part of MIT's Global Sentiment Project adds this crucial, often missed layer to understanding climate change's human cost. It pushes us beyond just economics or physical health to really integrate the psychological, the emotional toll.

Speaker 1: 12:08

It's not just a warmer planet. It's potentially a more irritable, more negative collective human experience.

Speaker 2: 12:14

It's a clear call, really, to make emotional well-being a fundamental part of climate policy and adaptation.

Speaker 1: 12:21

worldwide. Absolutely. Goes so much deeper than we might think. And that leaves us with a pretty provocative thought, doesn't it? As global temperatures keep rising and our collective mood potentially shifts towards this negativity, how might that impact things? Social cohesion, political stability, even just our personal relationships in ways we haven't fully grasped yet. What steps, big or small, can we start thinking about now as individuals, as communities, to foster that emotional resilience in a warming world? Something to really sit with, I think, long after this deep dive ends.

Speaker 2: 12:54

Thanks for listening today. Four recurring narratives underlie every episode. Boundary dissolution, adaptive complexity, embodied knowledge, and quantum-like uncertainty. These aren't just philosophical musings, but frameworks for understanding our modern world. We hope you continue exploring our other podcasts, responding to the content, and checking out our related articles at Heliox Podcast, dot substack dot com.