Is global climate change causing the brain to become "out of control"?

Leviathan Press:

In a previous article titled "The Weird Biting Methods of Ticks," the authors pointed out that as the global climate changes, the risks posed by ticks are increasing because they have the opportunity to expand their geographic range and penetrate new hosts. In North America, the lone-star tick and the black-legged tick are working closely together to advance northward into Canada.

I have seen a chilling video report before: due to the warm winter, the number of overwintering ticks increased sharply, and the reindeer were covered with dense ticks, and finally died from being sucked blood.

This is just a very small ecological change caused by climate change. Perhaps as the author of today's article said, with the emergence of more and more extreme climates, our brain may be becoming one of the most vulnerable areas to climate change - and this is by no means an exaggeration.

In February 1884, the English art critic and polymath John Ruskin took to the stage at the London Institution to deliver two lectures on weather. “The Storm Clouds of the Nineteenth Century” was his angry attack on a particular “wind of darkness” and “clouds of pestilence.”

July Thundercloud in the Val d'Aosta, John Ruskin, 1858. © Wikipedia

In his view, this phenomenon had only begun to engulf Victorian cities in recent years. He told his skeptical audience that he had been taking careful meteorological measurements. He denounced the "bitterness and malice" of this new weather and, perhaps more importantly, how it reflected a "moral haze" in society.

He suggested that people could understand the human condition themselves by observing the weather.

That February, as perhaps today, it would have been easy to dismiss the so-called “wind of darkness” as the ravings of a madman. Clouds were clouds: even if the clouds Ruskin described did exist (a point that was disputed at the time), it’s hard to imagine them having anything to do with the human psyche. As Brian Dillon noted in a 2019 essay in The Paris Review, it’s hard to tell the border between Ruskin’s “bad weather” and his own broken, sad state of mind.

Ruskin suffered a nervous breakdown while lecturing at Oxford in 1886. By the end of his life at the turn of the century he was widely regarded as mad. His writings on meteorology and the human spirit were not taken as seriously as his work on JMW Turner.

Constantin Meunier, The Mining District (1852-1905). © Wikipedia

Yet, for Ruskin, these clouds were more than just clouds: they were fed, as he noted in his diary, by a “heavy fog of manufactures.” The “plague clouds” symbolized the miasma of the Industrial Revolution; a moral haze caused by the rapid social and environmental changes then underway. Ruskin’s time saw pastoral landscapes being ruthlessly transformed into industrial centers. The air was thick with sulfur and misery. The soot-laden air, the chemicals and human waste, the din of machinery—these were not just physical annoyances, they were an assault on the senses, shaping mood and behavior in ways not yet fully understood.

Ruskin believed that the relentless pace of industrialization, with its tools, huge factories, and environmental destruction, had damaged people’s mental health: the mind, like the body, needed a healthy social and physical environment to thrive. This was actually a fairly new idea (Isaac Ray, the founder of the American Psychiatric Association, didn’t define the concept of “mental hygiene,” a precursor to mental health, until 1893). For Ruskin, an unstable environment led to an unstable mind. The two mirrored each other.

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More than a century later, the “plague cloud” is upon us again as we grapple with a new set of dramatic environmental changes. Average global surface temperatures have risen by about 1.1°C (2°F) since pre-industrial times, with most of that warming occurring in the past 40 years. Glaciers are melting, sea levels are rising steadily, and storms are raging.

© Behance

Yet the most common story remains that of the external world: the world outside our bodies. The climate change narrative is about extreme weather, economic upheaval and biodiversity loss. But perhaps we need to take that possibly mad Ruskin seriously: what about the clouds within us? As the climate crisis creates extreme weather, acidifies the oceans and breaks temperature records with frightening regularity, one has to ask: are our hearts changing too?

Here are some worryingly positive answers.

Immigration judges are less likely to rule in favor of asylum seekers on hot days. Students learn a quarter less effectively on warmer days than on milder days, and a warmer school year is often associated with lower learning outcomes. Temperature can also affect rates of online hate speech. Domestic violence incidents surge as the weather gets hotter.

However, you may already feel this way.

© Giphy

You may be more short-tempered on a hot day. You feel a little sluggish, have trouble concentrating, and are more likely to act impulsively. Numerous studies in cognitive neuroscience and behavioral economics provide evidence to support these behaviors. Drivers honk their horns more often (and for longer) in warmer temperatures. Hot weather also predicts harsher penalties at sporting events. In baseball, pitchers are more likely to hit batters on hot days, and outdoor temperatures are more predictive of their tendency to retaliate in kind if they witness an opposing pitcher doing the same thing.

In other words, the “plague cloud” seems to exist within us as well.

This shows the interconnectedness of our inner and outer worlds, exposing a certain fragility of human autonomy, that many of our decisions are more influenced by the environment than we intuitively think. It also shows the climate crisis in a whole new light: yes, as the climate changes, we are changing too.

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The London Institute where Ruskin spoke closed in 1912. Today, when you want to rail against the adverse effects of the environment on the mind, you publish a paper in The Lancet. That’s what 24 British clinical neurologists did in May 2024, arguing that “the incidence, prevalence and severity of many neurological diseases” could be affected by global warming.

For these researchers, led by Sanjay Sisodiya, professor of neurology at University College London, UK, global climate events are really the story of the clouds within us.

© Adobe Stock

In a survey of 332 scientific studies, Sisodia and his colleagues showed that climate affects people far more than expected, reaching deep into the fissures of the brain's cortex. Migraines, strokes, epileptic seizures and multiple sclerosis all appear to be linked to temperature.

Outside of hospitals, climate change is expanding the ranges of infectious disease vectors such as ticks, mosquitoes, and bats, and scientists predict an increase in the incidence of vector-borne and zoonotic brain diseases such as yellow fever, Zika virus, and cerebral malaria. It is clear that a changing environment can affect sensory systems and perception, reducing the efficiency of sensory processing of information. Warming freshwater can lead to blooms of cyanobacteria, which release neurotoxins and increase the risk of neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS).

© The Japan Times

Indeed, recent research suggests that climate change may be exacerbating the already debilitating burden of neurodegenerative diseases such as Parkinson’s and Alzheimer’s. In countries with above-average temperatures, more intense warming has been linked to an increase in Parkinson’s cases, and as Sisodia and others point out, the countries where dementia rates are expected to grow fastest will be those most affected by climate change.

Similarly, short-term exposure to high temperatures appears to lead to higher emergency room visits for Alzheimer’s. The air we breathe may also play a supporting role: in Mexico City, for example, where people are exposed to high levels of fine particulate matter and ozone from an early age, autopsies showed that 99% of people under the age of 30 had Alzheimer’s pathology.

Nor are the risks limited to living people.

A 2022 epidemiological study showed that exposure to heat in early pregnancy significantly increases the risk of schizophrenia, anorexia and other neuropsychiatric disorders in children. High temperatures during pregnancy have long been known to delay neurodevelopment in rats. Other scientific studies have shown that fetuses experiencing natural disasters in the womb significantly increase their risk of anxiety, depression, attention-deficit/hyperactivity disorder and behavioral disorders later in life.

These impacts put intergenerational responsibility in the Anthropocene under new and harsh scrutiny—most of the research is ongoing, and we don’t know what impacts will be in the future. What we do know now is that in study after study, the brain is emerging as one of the most vulnerable areas to climate change.

Back to the question of honking horns and baseball pitchers.

Focusing on the brain can provide some potential mechanistic explanations for these case studies and allow us to avoid using phrases like “winds of darkness.” For example, heat seems to shift functional brain networks (which coordinate behavior across regions) toward random activity. In extremely hot weather, scientists have noticed an overload of the dorsolateral prefrontal cortex (dlPFC), which Robert M Sapolsky, a neuroendocrinologist at Stanford University in the United States, calls “the ultimate rational decision-maker in the frontal cortex.”

The dorsolateral prefrontal cortex limits the extent to which people make impulsive decisions; and disruptions in dorsolateral prefrontal cortex activity often mean an increase in the relative influence of the limbic system (such as the amygdala, which is responsible for emotion regulation) on behavior. The higher the temperature, the less rational decision-making.

The physical effects of the environment on the brain are not limited to the dorsolateral prefrontal cortex. For example, heat stress in zebrafish downregulates the expression of proteins associated with synapse building and neurotransmitter release. In mice, heat triggers inflammation in the hippocampus, a brain region essential for memory formation and storage. While neuroinflammation often plays an initial protective role, chronic activation of immune cells such as microglia and astrocytes can become detrimental because pro-inflammatory molecules may damage brain cells in the long term. In humans, overheating is associated with reduced blood flow to the region. Psychologists' observations of decreased cognitive performance and increased aggression in high temperatures make perfect sense in the context of these findings.

The emerging environmental neuroscience is trying to “understand the qualitative and quantitative relationships between the external environment, neurobiology, psychology, and behavior.” In search of a more specific neologism — since that particular phrase also includes environmental exposures like noise, urban development, lighting, and crime — we could call this emerging, comprehensive field climate neuroepidemiology. Or, I don’t know, maybe we need a more TikTok-friendly name. Neuroclimatology? Ecological neurodynamics?

© PBS

I prefer to call it: the weight of nature.

This burden compels us to act, just as the behavioral effects mentioned above do. When extreme heat gets to the heart of you and makes you more inclined to violence, it actually constrains your options. Impulsive decision-making inherently means less consideration than deliberate decision-making; if climate change affects our reactions and decisions, we should understand it as undermining our sense of free will.

The weight of nature is heavy. It overwhelms us.

It’s also a heavy psychological burden. You may be familiar with the concept of “climate anxiety.” The phrase generally refers to a near-pathological worry and fear of impending environmental damage, but it’s never struck me as particularly identifying. Anxiety is often described as “excessive” worry, as defined in the Diagnostic and Statistical Manual of Mental Disorders (DSM).

I don’t think there’s anything “excessive” about seeing the clear signs of climate change and feeling a sense of impending doom.

© Corporate Knights

Perhaps we should think that those with climate anxiety have more developed brains than others - Cassandra (a Trojan princess and priestess of Apollo in Greek and Roman mythology. She had the ability to predict because the sacred snake washed her ears with its tongue or because Apollo gave her the ability to predict, but because she resisted Apollo, her predictions were not believed. Editor's note) may be the only sober person left.

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I'm not kidding. Neuroscience has begun studying the brain in this way, and not in vain.

For example, in a 2024 study, researchers at Northern Michigan University (NMU) found that people who reported higher levels of climate change anxiety showed different patterns in brain structure and function compared to those with lower levels of climate anxiety, particularly in the midcingulate cortex, a central hub in the brain responsible for threat detection.

Specifically, climate-anxious brains appear to have a smaller midcingulate cortex (in terms of gray matter), but one that is more functionally connected to other key hubs in the brain's salience network, a system thought to constantly scan the environment for emotion-relevant information. In the salience network, the midcingulate cortex works closely with the limbic system (such as the amygdala and insula) to prepare appropriate responses to this information. In climate-anxious people, this network may be particularly sensitive to climate-related threat signals.

Therefore, rather than a deficit, a smaller midcingulate cortex may reflect a more efficient and sophisticated threat detection system.

The brain is known to prune redundant connections over time, retaining only the most useful neural pathways. The Michigan researchers suggest that selective pruning may allow climate-anxious brains to process worrisome information more efficiently, facilitating rapid communication between the midcingulate cortex and other areas involved in anticipation and response to threat. In other words, they write, the midcingulate cortex of climate-anxious people may exhibit “more efficient neural connectivity.”

This neural sensitivity to potential danger has both advantages and disadvantages. On the one hand, it may make some people aware of real future dangers. The midcingulate cortex is critical for predicting future threats, and a meta-analysis found that the area is consistently activated when people think about unpredictable negative outcomes. Given the looming specter of climate disaster, a hair-trigger threat-detection system may be an adaptive asset.

On the other hand, the researchers believe:

The complexity, uncertainty, and temporal and geographic distance of the climate crisis, combined with its global nature, can cause individuals to underestimate the risks associated with climate change or to become overwhelmed and detached from reality—a state sometimes referred to as “ecological paralysis.”

Overactivity in the midcingulate cortex has been linked to clinical anxiety disorders, and the new findings suggest that climate anxiety is linked to some of the same neural underpinnings (although it’s important to remember that climate anxiety appears to be distinct from generalized anxiety, as the brain differences observed in the Michigan study couldn’t be explained by overall anxiety levels).

Although these findings are only speculative, they suggest that climate anxiety is not just a sociocultural phenomenon but has theoretically identifiable neural correlates. They offer a potential biological framework for understanding why some people are more vulnerable to the psychological effects of climate change than others. They also raise the intriguing question of whether the brains of climate-anxious people are particularly well-suited to cope with the existential threat of global warming, or are simply overwhelmed by it.

But in any case, these all show that the outside world is penetrating deeper into our hearts.

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Maybe there's another side to this. The changing climate is permeating our neurobiology. What does it mean to adapt our neurobiology to climate change?

That’s the premise of a 2023 article in Nature Climate Change by neuroscientist Kimberly Doell of the University of Vienna in Austria and colleagues. They argue that the field has important potential to help us understand climate adaptation responses and facilitate conservation decisions. Since Raskin’s angry interrogation of the environment, environmental neuroscience has explored the interrelationships between organisms and their ecological niches. We now know that the texture of the modern environment—green spaces, urban sprawl, socioeconomic hierarchies—leaves its mark on the brain. Climate change is no exception.

Therefore, Doerr and others believe that scientists and advocates can combine findings from neuroscience to improve communication strategies aimed at promoting climate action. They hope to use insights from neurobiology and cognitive neuroscience to more effectively design climate solutions—both within ourselves and for society as a whole.

We already have models for this type of approach.

Poverty research, for example, has long linked socioeconomic conditions to poor health. In recent years, neuroscience has examined how the various factors of poverty—toxic exposure, chronic stress—erode neural structures and interfere with cognitive development. While brain science alone cannot solve poverty, even a limited understanding of these mechanisms has led to research on programs such as Head Start, a home-based preschool curriculum that has been shown to improve selective attention and cognitive test scores.

While structural inequality is not easily eradicated, neuroscientists have successfully uncovered the neural correlates of poverty, mapped its reversible harms, and designed precise remedies accordingly. Doll and her colleagues believe the same potential applies to the neuroscience of climate change.

© EdSurge

To realize this potential, however, we need to better understand how the fever dream of the Anthropocene has already altered our wetware. The social and behavioral sciences have begun to document the psychological consequences of planetary change, but the neurological taxonomy of climate change remains to be explored. The field’s methodological and conceptual repertoire is ready for the challenge, but honing it will require alliances with fields as diverse as climate science, medicine, psychology, and political science.

The central question is: In a biosphere where change is the only constant, is the nervous system plastic enough to keep pace, or will it struggle to adapt?

The first wave of researchers taking up Kaveri’s challenge are studying a range of different organisms, each uniquely positioned to reveal the brain’s resilience in the face of Earth’s disruptions. For example, Wolfgang Stein of Illinois State University and Steffen Harzsch of the University of Greifswald in Germany are focusing on crustaceans, trying to understand how their neural thermoregulators respond to rising temperatures in both shallow and deep waters. Another team is targeting the brains of cephalopods, animals whose RNA editing abilities may be key to their ability to tolerate drastically falling oxygen levels in increasingly stifling aquatic habitats. A third Kaveri team, led by Florence Kermen of the University of Copenhagen in Denmark, is subjecting zebrafish to extreme temperatures, searching for molecular signatures in their neurons and glial cells that allow them to thrive — even as their watery world heats up.

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The brain, that cavernous command center atop the spinal cord, has long been a black box. As the climate crisis intensifies and the ecological foundations beneath our feet become more shaky, the need to peer inside the brain becomes more urgent. We are already beginning to see the outlines of the new neural map that Sisodia and his colleagues have sketched out.

We now know that the brain is less a static, self-regulating organization than a dynamic, living landscape, its hills and valleys shaped by the contours of our environment. Just as the Greenland ice sheet groans and buckles under the heat of climate change, so too will our synapses wither and our neurons disappear as the mercury rises. Just as rising seas engulf coastlines and forests succumb to drought and fire, so too will the anatomical boundaries of our brains be redrawn with each new onslaught of environmental aggression.

But the dialogue between the brain and the biosphere is not a one-way street. The choices we make, the behaviors we pursue, the ways we respond to crises—all of these decisions are reflected in the environment, for better or for worse. So I propose: in seeking to understand how a changing climate shapes the contours of our thinking, we must also consider how to update the architecture of our thinking in the service of sustainable development.

The cartographers of the Anthropocene mind face a daunting task. But in the hands of neuroscience—with brain scans, buzzing electrodes, the precision of gene editing, and the power of algorithms—it is possible to get close to a starting point. By tracing the paths of environmental influences to their neural roots, we may begin to unravel the complex web that ties the mind to the fate of the planet.

© wikipedia

One thing is clear: As the gears of the climate crisis continue to turn, our brains will be caught up in it. The question is, will we be passive passengers, or will we seize control and steer toward a livable future? The weight of nature—the enormity of the crisis we face—is daunting. But it won’t paralyze us. Dot by dot, synapse by synapse, we can chart a course through the gathering cloud of plague.

Ruskin once said, in one of his more lucid moments, "To eliminate imperfection is to destroy expression, to inhibit effort, to paralyze energy." Even if we could somehow do that, we should not eliminate the so-called imperfections in the effects of environment on the mind. Instead, we should read in them the intimate and vital relationship between self and world.

By Clayton Page Aldern

Translated by tamiya2

Proofreading/Rabbit's Light Footsteps

Original article/aeon.co/essays/how-a-warming-earth-is-changing-our-brains-bodies-and-minds

This article is based on the Creative Commons License (BY-NC) and is published by tamiya2 on Leviathan

The article only reflects the author's views and does not necessarily represent the position of Leviathan