Like a lot of people, Richard Seymour, 47, was trying to quietly ignore the climate crisis and get on with his life. As a prolific Marxist intellectual, this meant industriously writing about a range of subjects: the Iraq war, neoliberalism, the class struggle. The climate crisis could wait until after the revolution. Besides, he didn’t have the expertise or emotional capacity for it.

But in 2015 that changed. Walking in a local park on Christmas Day, he couldn’t ignore how noticeably warm it was. He started to think about not just what has already been lost but what global heating means for the losses to come. “Some sort of defence just went down,” he says, “and I experienced a preliminary bit of climate mourning.”

Seymour grew up in a small town in Northern Ireland surrounded by farmland, rivers and woodland but for years he’d been flexing what he calls a “hyper urban” attitude – it was in New York and Paris where the labour movement historically flourished and so it was in those kinds of environments that he felt he and his politics most belonged. But on that winter’s day, he remembered “growing up in nature and having an emotional attachment to it” – from the Mourne Mountains to the Giant’s Causeway. “It struck me that although things will go on in a way, nothing like that will ever exist again, it’s gone … And the things that I enjoy now, you know, they’re going to go too.”

Seymour set about reading all he could, from oceanography to evolutionary theory. Now he is, arguably, one of the UK’s foremost thinkers on the politics of climate breakdown and nature loss. In his regular Patreon and podcast appearances, Seymour – who is clearly something of a polymath – effortlessly joins the dots between environmental collapse, the rise of the far right and the role our desires play in a crumbling world, all while retaining his Marxist roots. As the Swedish scholar Andreas Malm asks on the front cover of Seymour’s new book, Disaster Nationalism: The Downfall of Liberal Civilization, “What thinker would you bring to an Earth on fire? You would not want to leave Richard Seymour at home.”

Our emotional responses to the world around us is one of the things that interests Seymour most. When we meet in the British Library to talk about his latest work, it’s this theme we keep circling back to.

Comparing the success of the far right in India, Brazil and the US (among other places), Seymour argues that most explanations for their rise are insufficient. What we’re seeing is “too consistent over time and too global, to be explained by local factors such as the backlash of a fading white supremacy, or Russian troll farms, or ‘bad actors’ spreading disinformation,” he writes. These movements also don’t have the hallmarks of historical fascism. “Their immediate objective is not the overthrow of electoral democracy,” Seymour observes, but “a constitutional rupture breaking with all humane and ‘woke’ constraints on the exercise of power.” While the old establishment decomposes, the far right conjures up apocalyptic images – “the great replacement”, “Islamisation”, “Chinese-style communism” – to animate potential supporters. This is not yet a distinct form of fascism; instead, it is what Seymour calls “disaster nationalism”.

An examination of the far right globally, Disaster Nationalism isn’t strictly about the climate crisis. But they are clearly connected. While disaster-laden fantasies capture imaginations, the environmental crisis lurks in the background. Seymour wants to interrogate this: why is fictional collapse so appealing, so exhilarating, when we live in a world of already existing, real disasters?

If people are miserable, insecure and humiliated, the far right offers a specific remedy in disaster nationalism, Seymour argues. “It offers the balm, not just of vengeance, but of a sort of violent reset which restores the traditional consolations of family, race, religion and nationhood, including the chance to humiliate others.”

Applying a psychoanalytic lens, as the American writer Tad DeLay does too, Seymour avoids commonplace and often sympathy-tinged characterisations of the far right as a cry of the working class (the “left behind”). The economy matters somewhat – he says a trajectory of decline fuels many middle-class people’s radicalisation to the right – but the roots of these movements often aren’t proletarian.

“All of these formations start off with a fairly middle-class voter base,” he tells me. “That’s certainly true of Bolsonaro, Duterte and Modi, and after a term in office, they have begun to build a real cross-class coalition, which is incredible.”

Anyone familiar with Seymour’s writing will know that he takes racism, sexism and transphobia seriously. When we talk, he speaks about these forms of bigotry with the same sophistication he brings to his writing and manages to do so while forgoing one of the other mainstream explanations of the far right’s rise, where voters are dismissed as gullible idiots who need to be shown the error of their ways – and of their information sources.

“If I agree to fantasise about gruesome, erotically charged scenarios for whose reality I’ve been given no good evidence, I am not simply lacking ‘critical skills’ or ‘media literacy’: the fantasy is doing something for me. It is staging something that I want, even if I don’t want to want it. And if that fantasy is then adopted by numerous others, for no good reason, then the wish obviously isn’t reducible to personal psychopathology but is rooted in a shared social condition,” he writes in Disaster Nationalism.

And that shared social condition is crucially affected and shaped by climate breakdown. The 2020 Oregon wildfires are illustrative, sweeping through the western US state after a series of chronic disasters: the credit crunch, skyrocketing rural poverty, alcoholism, suicide above the norm and a breakdown of local news, leaving Facebook and Nextdoor to fill the void. But when mostly white, rural, conservative Christians see the fires, it’s not climate change or capitalism they blame.

Spontaneously – not orchestrated by any one person or politician – it is the conspiracies they’ve heard that make the most sense of something so large and so destructive: Antifa, doing the bidding of the Democrats whose aim is to usher in communism, are to blame, wanting to kill people like them to remake America. Ideas like these spread like a contagion and the threshold for their uptake isn’t necessarily that high. As the fires rage, people refuse to leave, Seymour notes, so they can physically protect where they live from the arsonists they believe are behind all of this.

Ecological disaster transforms into disaster created by human evil; the climate crisis turns into a crisis of interpersonal rivalry, aggression and victimhood. The destruction of the planet creates the structural conditions for these ideas but it wouldn’t be possible if they weren’t already circulating, Seymour argues.

And he’s clear on why they’re so effective. “You can’t shoot climate change, you can’t take it to court, the same thing with capitalism. These are big, abstract forces, and you feel kind of hopeless against them,” he says. It’s far more attractive, exciting even, to “attack a personalised enemy”. All of us are susceptible to this, Seymour maintains – “There’s jackboots for all of us”, he reminds me at the end of our interview – albeit not equally.

I ask him about the left’s attempts to try a similar tactic and personify capitalism – for example, Bernie Sanders’ crusade against billionaires. He says they’ve had some success but it’s not so easy to play the far right at their own game. The ultra-rich live on another planet – you might see Jeff Bezos on TV, but you’re never going to meet him. Whereas people feel they know immigrants or Muslims and, if you read the news, you’ll be offered up these people as deviants every single day, Seymour points out.

The left has also been derailed by the idea that self-interest exhaustively explains how people behave. “I am not suggesting that bread-and-butter politics is superfluous. It will help,” he writes “we do need bread and butter. We even like it. But we don’t love it. And the things we do love often don’t give us any material benefit whatever. You might love your children, for example, but it isn’t because they increase your income and free time.”

Hope-scolds, as he calls them, miss the point when they caution that greens who doom-monger about the state of the world will demotivate people; recognising the end may be imminent can have the opposite impact, he argues. “People can be affected by climate disasters and draw wildly varying conclusions from it. But when they find other people who have the same response and who want to do something about it, they bond over it,” he explains.

“Too often, leftist talk about ‘organisation’ is abstract, making it sound like the issue is one of correct ideas and procedures,” he says. Instead, it should mean creating a form of life where people need each other. We already see this in unions, where people might join for better wages but end up striking to defend their comrades, even if they lose pay.

Seymour experiences this solidarity when he volunteers at his local church, which supports people who are homeless, many of whom are refugees. “I’m surrounded by people who do this all the time … they bring in stuff that they’ve made, they bring in stuff they’ve bought, they give up their free time for other people, no questions asked. The rule is … [you have to show] unconditional love for whoever walks in the door” - no matter who they are or what they’ve done.

This might all sound a bit too “universal peace and brotherhood”, he acknowledges, while still retaining his sardonic edge. But “if you imagine that you live in a planet where everything alive around you is purposive and has an intentional relationship to you and the rest of the world … I think that motivates better behaviour.”

For Seymour, then, comradeship isn’t just between humans, but between species and the living world. This is surely the bedrock of not just socialism, but eco socialism.

To better understand this and what we’re losing, it makes more sense to talk about mass extinction than just climate change, he tells me. “It pertains to the destruction and decay and etiolation of life across the board and all the evidence suggests we’re in what some call the end – Holocene mass extinction.” And extinctions reveal all our unacknowledged dependencies; we need plants and other animals. We, human beings, do not sit at the top of a grand hierarchy. Continuing as we are, exploiting other animals and the rest of nature, is unsustainable.

“If you want a less fancy way of putting it: love,” says Seymour. This isn’t necessarily where all Marxists might end up but he adds, “if we’re talking about socialism, what else are we talking about?”

• Disaster Nationalism by Richard Seymour (Verso Books, £20). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.