What Climate Change Is Doing to Our Brains

Thinking is physical. Thankfully, one of the many wonderful things about the human brain is that we don’t have to confront this unsettling fact very much — that the environment around us shapes our perceptions and reactions, that all human experience is the result of secreted hormones and synaptic transmission. In other words, our brains let us think we’re in charge.

Unfortunately, as with so many other things, climate change is interfering. “As the environment changes, you should expect to change too,” writes author, neuroscientist, and Grist senior data scientist Clayton Page Aldern in his gripping new book, The Weight of Nature: How a Changing Climate Changes Our Brains. “It is the job of your brain to model the world as it is,” he goes on. “And the world is mutating.”

You may already be familiar with some of his examples — that the heat can make us dumber and more aggressive, and that people who survive traumatic weather events can get post-traumatic stress disorder. But Aldern’s book — which, in spite of its author’s technical background, is immensely readable and literary — pushes far past the familiar, touching on topics as wide-ranging as brain-eating amoebas, language death, and free will. The common theme throughout, though, is that climate is our unseen “puppeteer.”

Our conversation has been edited and condensed for clarity.

You use the phrase “the weight of nature” in several contexts throughout the book. It made me think of both Altas, as in “the weight on our shoulders,” and also the idea of determinism that you get into a bit. At what point in the writing process did you come up with the title?

It was early on that the title came to me, but it was not the original title. I’ve been working on this project for six or seven years, and initially my working title was something awful like Nature’s Marionette, which sought to communicate this notion of forcing our hands — the puppetmaster behind our decision-making.

But I wanted to be able to communicate this feeling of being guided by the environment — in addition to carrying said burden — because it felt like weight. It does feel heavy, and heaviness does a lot of things, including forcing our hands.

Is there something about brains that makes them uniquely vulnerable to climate change? I ask because I’m sure books could be written about how climate change hurts our hearts or lungs, too. But it seems to impact our brains in a variety of terrifying forms.

Hearts do one thing: They beat. Brains are always reaching outward, and so, by extension, they’re enmeshed in the same manner in which one can imagine our entire bodies to be enmeshed in this “environment.”

More specifically, in addition to the reaching-out action, brains are actively modeling the world around us. That is what they do. This notion of having an active organ, as opposed to a somewhat passive organ, makes the difference because brains are always integrating new information about the world. And the world is changing.

As we come to terms with this changing world — and when I use the phrase “come to terms,” I’m not seeking to deploy some kind of intellectual or emotional metaphor here. I mean, on a biophysical level, as we’re coming to terms with these changes — then neurochemical changes result accordingly. We respond in kind. Certainly, our other organs are adaptive to various degrees, but the whole point of the brain is its adaptive nature, right? It seeks to model the world around us, and it implements change through a system known as neuroplasticity. It is an organ that is built for modeling and integrating change. And so, is it any wonder that climate change acts directly on this organ in ways it may not act on others?

The chapter about Karl Friston and the give-and-take of perception — in which you write, “our actions are the world’s sensations, and our sensations are the world’s actions” — completely blew my mind.

I haven’t even told this to my editor, but I think if I’m ever granted the privilege of writing a book again, I might try to pitch a biography of Karl Friston. His research is unbelievably interesting.

Is his work well-known among neuroscientists, or is it kind of fringe even within the community?

That’s a fabulous question, and I'll tell you why: Karl is one of the most cited neuroscientists of all time, but most neuroscientists have not heard of him. The reason that paradox is true is because, early in his career, he developed some of the basic algorithmic technology underlying functional resonance in functional magnetic resonance imaging: fMRI. And so, anytime anybody uses fMRI, which most neuroscientists do, there’s this casual Fristonian citation that goes back to his early work.

Far fewer people have paid attention to his groundbreaking work on what’s called the free energy hypothesis. If you Google, like, “the most influential neuroscientists of all time,” he’s always on these lists, but nobody knows who he is. Well, nobody is a stretch; he’s reasonably well-known in sub-communities. But by and large, he’s such an abstract thinker, and his material is so difficult to internalize, that most people who are attracted to his work fall into the neuro-theory community, computational neuroscientists, theoretical neuroscientists — and that’s, frankly, the vast minority of neuroscientists. So he is somewhat of an unknown entity, which is just astounding because he has literally been in the running for the Nobel.

Something that struck me was how many gaps there are in the science of understanding our own brains — we often seem to know the general region where thoughts or impulses originate but not quite the mechanics of how they work. Are there certain mysteries about our consciousness and perception that might always remain slightly out of our reach?

There’s a huge body of research that seeks to address whether or not the question of consciousness, and understanding it, is unravelable at all. This is known as the hard problem of consciousness. Have we made progress in our understanding of consciousness over the past 100 or 200 years? Well, almost certainly, yes. And in neuroscience, we’ve come closer to an understanding of what perception is and what consciousness is.

Will another 20 years or so get us closer to an ultimate, grounded, and internalized rational scientific representation there of? Maybe! But there are also people today who argue with just as much empirical backing that the notion of solving consciousness — the notion of, basically, a self coming to understand itself — is a logically impossible act.

I’m not a consciousness researcher, so I’m not sure if I have enough background to really say that I’ve made my mind up. But there are certainly folks out there who say consciousness is not something that’s solvable, it’s not something that we will ever understand in the same materialistic terms that, perhaps, we understand the heart.

I’m going to be obnoxious and ask the AI question. You didn’t really get into the possibility and pitfalls of technology, but I’m wondering if it was back of mind at all while you were writing?

I’m going to give you an obnoxious answer. In fact, it’s a decades-old obnoxious answer. When I’m thinking about this stuff, my instinct is to think about technology in terms of the manners in which it removes us from nature. So much of the promise in this area of research — and I do think there’s promise, I don’t think it’s all doom and gloom — is that this intimate relationship we have with the planet is also that which can be leveraged to help mediate some of these detrimental effects.

There’s a fabulous book from a couple of years ago, The Nature Fix, by Florence Williams; I have come to understand my book as its dark version. The Nature Fix details all the manners in which interacting with nature, as opposed to the built environment, is essential for mental, psychological, spiritual, and neurological health.

This is an obnoxious answer because it’s the classic “Oh, kids are all looking at their phones!” But I think that’s real — the handheld devices and the omniscience of the all-knowing screen, which, perhaps we can extend that to the LLMs. As it were, there’s this suite of technologies that mediates our relationship both with knowledge writ large and the broader environment outside of ourselves. In my estimate, it filters the world in a way that I suspect is preventing us from interacting with some of the benefits that the environment has to offer.

The same things that make our brains incredible — their ability to adapt, create, and use language — are also what allowed us to invent the combustion engine, organize global commodities markets, and design machines for fracking. In a sense, the climate fight requires beating back against the weight and consequences of our own brains, right?

When I think about this question, it’s less about “how can we ensure we’re using the tools of evolution, the powers of the brain, for good,” and more about coming to terms with the fact that something like free will doesn’t exist.

There’s this thinker, Timothy Morton, who writes a lot about our enmeshment with the environment and the degree to which one cannot separate the self from the greater universe. Taken to its extreme, that thinking — which I think is very powerful — implies that what we need to wrap our heads around and come to terms with is the fact that we’re not really making decisions, per se. It’s just a universe of particles in motion. So grappling with what Morton calls the ecological thought, grappling with this notion of determinism and enmeshment, and trying to suss out the moral responsibilities that fall out of that relationship — that, to me, is a worthy task and, frankly, an unsolved problem.

As a neuroscientist working in the climate space, what keeps you up at night?

The 20-year timeline keeps me up at night. A lot of the research that we’re coming to terms with today is going to make itself known on a much more visceral level over the next 20 to 50 years. If it is in fact the case that cyanobacterial blooms are releasing a neurotoxin that is spurring an increased risk of ALS, that neurodegenerative disease isn’t necessarily going to manifest in people whom it is likely to affect for a number of years. We’re not going to see in tangible, visceral terms a corresponding spike in this disease in the general population for another couple of decades.

I just published a piece in The Guardian about some of these effects, and one of the researchers I interviewed for that piece basically said what I’m trying to communicate now, which is: We’re in the midst of a grand experiment. It’s not like a lab where you’ve got a rat, and you’re selectively exposing it to one toxin over the course of some fixed time period and measuring the results. The lab that we’re in is the Earth and we are exposed to climatic and environmental stressors in this soup, chronically, for years and years, and in unknown quantities. At some point, we’re going to look around and say, “Oh, this is really bad. We should do something about this.” And for many people, it will be too late.

What gives you hope?

I don’t like hope. I think that hope breeds complacency — or, at least, false hope does. I tend personally not to look for vectors of hope per se, which is not to say that I’m a pessimist or a nihilist or anything like that. I look for climate solutions, for example, or sources of resilience, or stories of the capacity of the human spirit that inspire me with a feeling of desire. I’m interested in having images out there in the world that point my compass toward a future that I would like to realize.