An article by a British professor that predicts the imminent collapse of society, as a result of climate change, has been downloaded over half a million times. Many mainstream climate scientists totally reject his claims, but his followers are already preparing for the worst.

As the last light of the late-winter sunset illuminates her suburban back garden, Rachel Ingrams is looking at the sky and pondering how long we have left.

Her hands shielded from the gusts of February air by a well-worn pair of gardening gloves, Rachel carefully places tree spinach and scarlet pimpernel seeds into brown plastic pots.

Over the past year, Rachel, 45, has invested in a greenhouse and four bright blue water butts, and started building a raised vegetable patch out of planks of wood. It’s all part of an effort to rewild her garden and become as close to self-sufficient as she can, while society continues to function.

Within the next five to 10 years, she says, climate change is going to cause it to fall apart. "I don’t see things lasting any longer than that."

So every evening, after picking up her children from school and returning to their former council house, she spends about two hours working outside.

"I find the more I do it, the less anxious I am," she says. "It’s better than just sitting in the living room looking at the news and thinking, ‘Oh God, climate change is happening, what do we do?’"

Rachel is unsure about how much to tell her three daughters. "I don’t say to them that in five years we won’t be here," she tells me. "But they do accept that food will be difficult to find."

Every six weeks, she takes her two youngest daughters on an 450-mile round trip from their home in Sheffield to an organic farm in South Wales, where they learn how to forage for food. It’s vital for them to learn "skills we’ll be able to use in the natural world when all our systems have broken down," she says.

"I don’t think what they’re learning in school is the right stuff any more, given what we’re facing. They need to be learning permaculture self-sufficient agriculture and other stuff, ancient stuff that we’ve forgotten how to do. We just go to Tesco."

But she’s not at all confident her efforts will make much difference, in the long run. "I don’t think we can save the human race," she says, "but hopefully we can leave the planet with some organic life."

Around a year ago, a video of a talk by a British professor called Jem Bendell appeared on Rachel’s Twitter feed.

"As soon as I saw it, everything seemed to make sense in a terrifying way," Rachel says.

"It felt like a bolt from the blue: ‘We’re all going to die.’ I felt it in my bones that we are at the beginning of the end."

Bendell, a professor in sustainable leadership at the University of Cumbria, is the author of an academic article, Deep Adaptation: A Map for Navigating Climate Tragedy, which has become the closest thing to a manifesto for a generation of self-described "climate doomers".

In it, he argues that it is too late for us to avoid "the inevitability of societal collapse" caused by climate change. Instead, we are facing a "near-term" breakdown of civilisation - near-term meaning within about a decade.

The paper was rejected for publication by a peer-reviewed journal, whose reviewers said its language was "not appropriate for an academic article".

It is certainly unconventional, with its disturbing descriptions of what’s to come. "You won’t know whether to stay or go. You will fear being violently killed before starving to death," Bendell writes.

After the journal’s rejection, in July 2018 Bendell self-published the 34-page article online.

It soon went viral. It has now been downloaded over half a million times, translated into a dozen languages, and sparked a global movement with thousands of followers - called Deep Adaptation, because Bendell calls on people to adapt their lifestyle to cope with the harsh conditions in his vision of the future.

But Bendell’s stark predictions have been dismissed by prominent climate scientists.

Prof Michael Mann, one of the world’s most renowned, describes Bendell’s paper as "pseudo-scientific nonsense".

"To me, the Bendell paper is a perfect storm of misguidedness and wrongheadedness," Mann says. "It is wrong on the science and its impacts. There is no credible evidence that we face ‘inevitable near-term collapse’."

What’s more, Mann claims, Bendell’s "doomist framing" is "disabling" and will "lead us down the very same path of inaction as outright climate change denial. Fossil fuel interests love this framing." Bendell is, he says, "a poster child for the dangerous new strain of crypto-denialism".

Myles Allen, professor of Geosystem Science at the University of Oxford, is just as critical.

"Predictions of societal collapse in the next few years as a result of climate change seem very far-fetched," he tells me.

"So far, the system’s responded to greenhouse gas emissions almost exactly as predicted. So to say it’s about to change and become much worse is speculation.

"Honestly this kind of material is at the level of science of the anti-vax campaign."

Allen agrees with Mann that the paper’s pessimism is liable to make people feel powerless. "Lots of people are using this kind of catastrophism to argue that there’s no point in reducing emissions," he says.

Bendell rejects the scientists’ claims and says people have been inspired by his paper to demand radical government measures to tackle climate change.

"I hope Michael Mann gets to meet some more climate activists on the streets, so he can meet the new breed of fearless people taking peaceful direct action after being moved by uncompromising assessments of our situation," he says. "Many of the leaders of Extinction Rebellion read my paper and quit their jobs to go full time to try to reduce harm and save what we can."

Other climate scientists say they have more time for Bendell.

"With global emissions continuing to rise, and no signs that the Paris targets will be respected, Jem Bendell has some justification in taking the strong position that it is already too late and we’d better prepare to deal with the collapse of the globalised economic system," says Prof Will Steffen, from Australia’s Climate Change Council.

"Jem may, in fact, be ‘ahead of the game’ in warning us about what we might need to prepare for."

He adds that there is a "credible risk" that even a 2C rise in global average temperatures above pre-industrial levels could initiate a "a tipping cascade… taking our climate system out of our control and on to a Hothouse Earth state".

"I can’t say for sure that Jem Bendell is right… but we certainly can’t rule it out."

In its bleak forecasts and direct language, Bendell’s paper has had an electrifying effect on many who have read it. Almost 10,000 people have joined a "Positive Deep Adaptation" Facebook group and about 3,000 are members of an online forum.

Here, the movement’s followers exchange ideas about how they can adapt their lives, businesses and communities in accordance with Deep Adaptation doctrine.

In the paper, Bendell proposes a "Deep Adaptation Agenda" - a conceptual roadmap for how to cope with the economic, political and environmental shocks he believes are coming our way.

He urges people to think about the aspects of our current way of life we will be able to hold on to and those we will have to let go of, referring to these two ideas as Resilience and Relinquishment.

He also talks about a third R, Restoration, which refers to old skills and habits that we will have to bring back. For some, such as Rachel, "restoration" means rewilding their gardens and local neighbourhoods, learning foraging skills and imagining how to survive in a world without electricity.

For others it’s about leaving the city or heavily populated areas of the country and heading for the hills.

Lionel Kirbyshire, a 60-year-old former chemicals engineer, says he began getting deeply worried about the climate a few years ago. He read, among other things, some of the writings of Guy MacPherson, a controversial American scientist unaffiliated to Deep Adaptation, who predicts humans will be extinct by 2030.

His head was soon "boiling with all this information that no-one wants to know".

"There was a moment about a year ago when it hit me and I thought, ‘We’re in big trouble,’" he says. "When you look at the whole picture it’s terrifying. I think we’ve got 10 years, but we’ll be lucky to make it."

A few months after reading the Deep Adaptation paper, Lionel and his wife, Jill, decided to move north. They sold their house in densely populated Bedfordshire and relocated to a three-bedroom terraced house in the small town of Cupar, Fife.

"In the back of my mind, I think when the crunch comes, there’ll be a lot of people in a small area and it’s going to be mayhem - and we’ll be safer if we move further north because it’s colder."

They expect their grown-up children will join them in the coming years. In the meantime Lionel is investing in some growing boxes, in order to create raised vegetable beds in his garden, a foraging manual and water purification tablets.

"We’re not stockpiling food but as the years go on I can’t see us having much left."

Another Deep Adaptation follower, who didn’t want his name to be published, told me he was planning to relocate from the South-East to the Welsh countryside.

"The basic things we’ll need will be food, water and shelter," he says.

He plans to live off-grid, either joining an existing eco-community or "going it alone" with like-minded friends in a house clad with straw bales for insulation.

"Deep Adaptation isn’t a bunker mentality of doing it yourself. You want a mix of people with different skills," he says.

But he also says he has been taking crossbow lessons, "because you never know".

"It seems like a pretty useful weapon to have around to protect ourselves. I’d hate the thought I’d ever have to use it but the thought of standing by and not being able to protect the ones I love is pretty horrifying."

Jem Bendell says Deep Adaptation advocates non-violence. Its online platforms ban members from discussing "fascistic or violent approaches to the situation".

Though it didn’t appear in Bendell’s first paper he later added a fourth R, Reconciliation, which is all about living in peace. And when I finally get through to him, after two months of unreturned emails and conversations with his colleagues in the Deep Adaptation "core team", he puts a big emphasis on love.

"People are rising up in love in response to their despair and fear," he tells me. "[Deep Adaptation] seems to have reached people in all walks of life, at least in the West - heads of banks, UN agencies, European Commission divisions, political parties, religious leaders…"

His message, he says, is one of "putting love and truth first".

At present, the professor’s followers often feel that their truth they believe in is ignored and dismissed by the rest of society.

Lionel says that among people he meets "no-one wants to talk about it".

He’s joined several online groups - with names like Near-Term Human Extinction Support Group and Collapse Chronicles - where he can share his despair.

"Sometimes I say that I’m feeling quite low and someone will say they’re feeling the same," he tells me. "So you know you’re not in it alone."

Rachel tells me that she also sometimes feels isolated. Her attempts to get her neighbours to collaborate in a community compost heap have mostly fallen on deaf ears, so she turns to Deep Adaptation’s online forums to find support.

"It’s much easier when you have a group to face the tragedy unfolding before us. If I am feeling anxious, hopeless or full of grief I can go on there and tell them how I’m feeling.

"There are 9,000 people all over the world, so you can post on there in the middle of the night and get support. I post ideas about my compost bin and get lots of messages back with people being encouraging."

However, she thinks there will be a day when the electricity is cut off, so she is learning to recite poems by heart, in case she finds herself alone, with no internet or possessions.

"At least I’ll have something to carry with me."