Visiting Barbara Kingsolver on her farm in Appalachia feels like entering some form of enchanted bower. As we drive through the nearby town of Abingdon, Virginia, she identifies some brightly painted wooden houses; the tavern built in 1779; the Barter theatre that’s been running since the great depression, when actors performed in exchange for food, trading “ham for Hamlet”. Then there’s her big, cosy farmhouse with its heavy wooden beams, Bartók and Satie sheet music on the piano (she went to college on a music scholarship and has played in various bands), and her border collie Hugo following her around as she quizzes me in unusual detail on how I like my coffee. “I’m southern,” she jokes. “I want to make you happy.” If all this sounds a little too idyllic, there’s nothing sugary about Kingsolver herself. Warm but brisk, she seems to have arranged this as a safe place from which to examine the many more alarming things outside it. Her new book, Unsheltered, a return to the more ambitious, grand scale of novels such as The Lacuna and The Poisonwood Bible (which she’s currently adapting for the screen), though lively and vividly peopled, is a novel of ideas, and bleak ones at that. It addresses a world coming apart at the seams. Willa Knox, laid off from her magazine job and trying to keep her family afloat, despite a series of disasters – a bereavement, crushing college debt and healthcare costs, vanishing investments – lives in Vineland, New Jersey, a former utopian community, in an old house that’s crumbling around her.

While attempting to keep the roof from caving in, she becomes interested in the people who lived in the same neighbourhood in the 1870s; they form the novel’s second strand. Thatcher Greenwood, a science teacher whose excitement about Darwin’s ideas puts him at risk of unemployment and who is newly and rather precariously married to the socially ambitious Rose, lives in the same building as Willa, with shoddy foundations above which “the whole house is at odds with itself”. Greenwood befriends the historical figure Mary Treat, a correspondent of Charles Darwin and Asa Gray, who spends her time on scientific experiments, keeping spiders in jars and letting carnivorous plants gnaw for hours at her fingers (Kingsolver showed me some of these plants in her own garden).

She decided it would be “useful to go back to some other moment in history when people felt a similar absolute disorientation in the universe”. She’d considered writing about Darwin himself, before deciding “I write American novels”, no matter how far afield they roam. “Such a sweet man!” she says. “Thank God there was no internet. People hated him so much. Emily Dickinson hated him, for God’s sakes! She didn’t hate anybody.” It’s “hard to understand now how threatening it was”, she says of Darwin’s ideas, for human beings to be told that in fact they weren’t “put here to be in charge of the rest of the world”. Her hope in Unsheltered was to explore “paradigm shift”. “What do people do when it feels like they’re living through the end of the world as we know it? Because that’s what it seems like we’re doing right now, and almost nobody disagrees. And maybe people said that 10 years ago, but now they’re really saying ‘WTF?’”

Like those in 1871, the characters in 2016 are struggling to come to terms with the realisation that all their assumptions and expectations in life, including their basic understanding of both natural and economic laws, no longer apply. The beliefs that “ice would stay frozen and there would always be more fish in the sea”, that growth and consumption could and should go on for ever, that hard work would pay off and that each generation would have more than the last, have been swept away. Whether now or at the fall of the Roman empire, Kingsolver says: “At the end of an era, people keep grabbing harder on to the world that they know.” See what happens, as she puts it, “when you put a bunch of rats in a box.” And of course when their material shelter is under threat, people tend to seek the safety of familiar ideas. She is not surprised that “we either choose or allow men to lead us who formed their notion of what is good and how to solve problems half a century ago, in the 1950s and 60s. Look at any picture of who’s running this country. They’re all old men in suits.”

Every economic catastrophe that befalls the fictional family, Kingsolver says, is something that has happened to someone she knows. Now “the end times have reached the inner circle” she believes it will “strip away a layer of denial” about how society actually functions. In the US until recently, “enough people have been comfortable enough to support the myth that we deserve what we have”, allowing for that “awfully American disease” of victim-blaming.

Clear throughout Unsheltered is a tension between self-reliance and interdependence. “That’s the dialectic,” she says, “the fundamental conflict that I think is at the heart of every single thing I write. That push-pull, that tug between the desire for individual expression, being a person who can take care of herself, and the necessity of relying on a community, all of the bonds that we don’t notice or don’t acknowledge.” It’s a theme that has preoccupied her ever since her ecology and evolutionary biology PhD on the genetics of altruism, which she abandoned after a “crisis of faith”, when, “lying in bed, counting in my mind the people on Earth who would read it, I came up with 11.” It’s not only an intellectual interest: “I saw a lot of unhappiness in the people who gave their lives over to service, a lot of frustration, a lot of misery, really. The women of my mother’s generation were a very unhappy lot. That’s why so many of them ended up taking Valium, I guess! And I didn’t want that.”

I’m a hillbilly. We look all kinds of different ways and this is one of them

Yet Kingsolver doesn’t seem the type to lose herself easily. She wrote her first novel, The Bean Trees, by night while pregnant with her elder daughter, Camille, working as a journalist during the day. She notes that her fierce insomnia was in some ways helpful: “Everyone has the same number of hours in a day – except me.” When Camille was late and the doctor recommended inducing the birth, Kingsolver refused an induction and used the extra time to get the book finished. Later, Camille and Lily, her daughter from her second marriage, knew never to disturb her when she was working. “There are two reasons you can knock on this door,” she remembers telling them. “Arterial bleeding; the house is on fire.” Joking aside, “they respected that. They knew that Mama was doing something important in there.” She had planned never to marry or depend on a man, feeling that “I’m not going to be that person who, you know, makes the meal and gets no credit. I think that’s in my psyche, the desire to self-define and also the thorough understanding that nobody really does self-define, no one is self-made. The bottom truth is that nothing functions in isolation.”

Abingdon, Virginia, in the early morning. Photograph: Fred R Conrad/The Guardian

At this point Kingsolver’s husband, Steven Hopp arrives to bring us lunch from his farm-to-table restaurant in Abingdon. He teaches environmental studies at Emory & Henry College nearby. When she notices a dead bird that seems to have crashed into a window, he identifies it immediately as a yellow rumped warbler. They met in 1993 when she came over from Tucson, Arizona, for a two-week visiting writer gig. By then a single mother living “in pretty dire straits”, she spoke to his global wildlife conservation class and “did such a good job that he just had to marry me, I guess”. Despite her misgivings about marrying at all, let alone for a second time, they kept in touch and began living together once “our phone bills surpassed our mortgages”, eventually settling on the farm in Virginia.

Kingsolver, who grew up in Kentucky, is treated as a local in Abingdon – several generations of her family had lived in the area, including a great-great-uncle who delivered the babies there for decades. “I’m a hillbilly. We look all kinds of different ways and this is one of them,” she says, complaining that she can hardly watch late night political comedy for the ignorant jokes at her neighbours’ expense. Even “well-meaning friends” have a skewed perception of the place where she lives. She understands why people in the middle of the country “feel the contempt of the people who are in charge of urban, progressive culture. That’s real. It’s pretty relentless and it’s gotten worse.” That’s one more reason she was intrigued by the 19th century, a time when “we had just been through this civil rupture where the country broke in half and it was as polarised as it is now, along somewhat similar geographic lines, which was instructive to think about.. Mainly rural versus urban, agrarian versus industrial, a rupture that has never healed.”

I saw a lot of unhappiness in the people who gave their lives over to service ... the women of my mother’s generation were very unhappy

Kingsolver likes nothing better than to take a difficult, “uncomfortable” subject – what the US did to the Congo, say – and spin it into the most appealing package she can find, so that readers and book clubs all over the world can enjoy wandering among her thorny questions. “I’m in a really unusual position,” she says, “because I work as a literary writer. I work at the level of the sentence, at the level of the image, the metaphor, the theme, but I also have this commitment to accessibility, which I suppose comes from the fact I grew up here. It’s the same reason I sent my kids to public schools: I want to belong to people. I don’t want to be above them. So I would really like anyone who can read to be able to read my novels and I would like to give them a reason to turn every page.” Journalists are often surprised that her books have such large ambitions. They ask questions that amount to: “Are you allowed to do this?” She notes: “Men don’t get asked that.” Nonetheless, she has an answer – she never studied writing. “I didn’t get an MFA in the 1980s and 90s, when everything was minimalism, saying that conflict has to be at the level of the marriage, or at most the grocery store. I didn’t know that’s what I was supposed to do, and therefore didn’t do it.”

It’s not only an aesthetic issue, though. “This country has been phobic for a long time about art that engages with real questions, matters of genuine social or environmental concern. I can write about my alcoholic father but not the economic forces that made him an alcoholic.” The Lacuna, set in the Mexico City of Diego Rivera and the US during the McCarthy period, was her “attempt to answer that question of what happened in this country to make people so wary of art with meaning. It’s so hard to see the fishbowl you’re living in.” Her launch of the Bellwether prize for socially engaged fiction, which has for two decades been awarding the amount of Kingsolver’s first advance to a new writer every other year, was another response. She notes that things have now begun to change, both in fiction and outside it. For instance, in the US, “a surprising number of people under 30 identify as socialists, or at least don’t identify as capitalists. They see that infinite growth is science fiction. They don’t really think we can just jump over to Mars and keep building cities.” That said, she speaks of “how discouraging it has been to raise daughters who ran up against the exact same crap that I did in terms of sexual harassment, and every kind of sexism.” Even the number of young women who still take their husbands’ names disturbs her – she can’t understand why it’s still so popular to “erase yourself”.

To the extent that Kingsolver is an optimist, it’s because she sees that as the only practical and conscionable option. When she tells me of her visit to Australia’s Great Barrier Reef earlier this year, a treat after turning in the Unsheltered manuscript, she’s quick to correct me about the direness of the reef’s fate. “Reports of its death are greatly exaggerated,” she says, and gives me a very swift, clear account of why these particular corals with their particular microclimates can still survive, heal and adapt.

“You’re hearing about everything that dies, you’re not hearing about everything that’s still alive,” she says. “If you think it’s dead already then you’re not going to be bothered. I almost think people gravitate towards ‘It’s too late,’ because then they don’t have to put themselves out.” And then, as if casually reminding me just why her fiction, that patient, painstaking evocation of worlds, makes sense as a response to an emergency, she says: “Only if you love something will you inconvenience yourself to work on its behalf.”

• Unsheltered is published by Faber. To order a copy for £15.49 (RRP £20) go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.

• Barbara Kingsolver will be speaking about Unsheltered at Southbank Centre’s Royal Festival Hall on 12 November 2018.