Shame can "devastate the soul and cripple the psyche", said the late self-help guru, Ben Bradshaw – and Glasgow University's chair of moral philosophy, Glen Pettigrove, goes further, pointing out that "untold numbers of people have committed suicide precisely because they couldn't face the shame" they were feeling.

The corollary is, of course, that shame is a powerful device for controlling behaviour and for centuries, societies placed offenders in the stocks or forced naughty children to stand in corners to warn of the humiliation in store for anyone who stepped out of line.

Thankfully, the dunce's cap is no longer considered a legitimate educational aid, nor is public shaming officially sanctioned by the UK criminal justice system.

“We'll go to crazy lengths to avoid looking bad in somebody else's eyes,” says Prof Pettigrove – a leading authority on the philosophy of emotions – adding that for much of human history, fear of public disgrace proved an effective way of enforcing societal norms. Around the middle of the last century, however, shame began losing its grip on Western psyches as close-knit communities dispersed, individualism gathered momentum and the spectre of Auntie Jean's disapproval lost its potency.

Now, though, thanks to social media, shame is experiencing a renaissance. Every other day, someone is outed over the internet after being caught behaving badly. Who can forget the case of communications executive Justine Sacco, who in 2014 landed in Cape Town to discover she'd become a worldwide pariah after tweeting mid-flight: “Going to Africa. Hope I don't get Aids. Just kidding. I'm white!” More recently, US anti-racism campaigners have been sharing footage of white folks apparently displaying casual bigotry in the streets. There was “BBQ Betty” (who complained about black people barbecuing in a public park) and “Permit Patty” (who threatened to call the police because an African-American child was “illegally selling water without a permit”).

So has social media recreated the halcyon days of communitarian values, when we all behave virtuously in order to avoid ignominy and ostracism? Lest we romanticise that apparent idyll, American law professor, Eric Posner reminds us, in the US journal, Slate, that “small-town societies bred small-mindedness and conformity, and if they were ever tolerable, it was only because one could leave. One can't leave the internet. Once shamed, always shamed”.

Both Justine Sacco and the woman dubbed “Permit Patty” lost their jobs and countless shamees have had their lives ruined. Does that matter, so long as social evils are exposed? In her book, Is Shame Necessary?, environmental studies professor Jennifer Jacquet argues that it is sometimes "the only available option – especially in international politics with issues like climate change commitments or human rights violations".

She credits “shaming campaigns” by organisations such as Occupy Wall Street and BankTrack with highlighting corporate greed and persuading financial institutions to reduce their investment in fossil fuels. And while she warns shame is a "dangerous and fickle instrument" best targeted at large groups, she doesn't exempt individuals, “especially not if they are politically powerful or sizeably impact society".

So could you or I soon find ourselves being publicly outed for environmental sins? Green campaigners have not so far resorted to exposing individuals for slipshod recycling or profligate diesel consumption. But are they missing a trick?

The Swedes already have a word, “flygskam", for the embarrassment we feel (or should feel) about air travel. The Finns, Dutch and Germans all have similar terms and in April, Emma Thompson experienced a “flygskam” moment when she was quizzed about jetting 5000 miles from Los Angeles to London for the Extinction Rebellion protest. "Unfortunately, sometimes I have to fly,” insisted the actor, somewhat peevishly, “but I don't fly nearly as much as I did, because of my carbon footprint and I plant a lot of trees."

"It's always turned back on the individual,” she continued, “but everyone has been asking for clean energy for decades and it has been ignored for decades. So where is the hypocrisy? If I could fly cleanly I would."

Yet until individuals show willingness to change, governments won't act and halting global warming requires each of us to reduce our personal carbon footprint. So is a little public humiliation a price worth paying if it helps save the world for future generations?

Glen Pettigrove warns that trial by mortification is fraught with dangers. "In legal contexts, we put strictures in place to ensure that the innocent aren't wrongly punished, but when we shame one another, that doesn't get carefully processed with all the evidence put before the jury before sentence is passed down. We almost never have full information with respect to what's happening in somebody else's life, [including] factors which have a bearing on the case."

Then there's the question of scale. "Even if it would be perfectly appropriate for a few people to apply pressure to you for flying needlessly, the kind of discomfort you feel as a result of a million people applying that same scrutiny would be dramatically out of proportion to what you deserve."

In his book, So You've Been Publicly Shamed, Jon Ronson compares humiliation by social media to delivering “remotely administered drone strikes” in that “nobody has to think about how ferocious our collective power might be”.

Cautiously administered, however, shame, says Pettigrove, is "sometimes the best tool we have to generate really important changes. We shouldn't stomach racist behaviours. There are things people are comfortable with that they shouldn't be comfortable with, and shame is an effective way of – if not changing their underlying feelings, at least changing their external behaviour.

"More importantly," he adds, "it's a powerful way of communicating to victims that we stand with them and this isn't OK. Sometimes shaming or being shamed is [a way of] giving voice to social protest. And if I'm going to protest – particularly a systemic evil – then the person whose current behaviour is the trigger for that, isn't responsible for all the evils that go with the system, they're just manifesting what's widespread. But if you're going to change that systemic problem then it might be the case that that individual serves as a kind of lightning rod to draw attention to a larger problem."

Like a sacrificial lamb?

"Yeah. Sometimes that's probably the right thing to do."

Will it work, though? In a Foundation For Economic Education paper, James Walpole warns that “public shaming enforces outward compliance, not internal change” – and it's worth bearing in mind that as well as “flygskam”, the Swedes have a word (“smygflyga”) for flying in secret. Tackling global warming requires radical changes of mindset rather than a “greenwashed” world in which we all proudly brandish our recycled jute carrier bags while privately turning up our thermostats and pouring toxins into the ecosystem.

And public health educationalists have long known that humiliating people for smoking or overeating can backfire, by simply making them indulge their habits in secret. In a paper on "shame-based appeals in a tobacco control public health campaign", scientists from California's Stanford Prevention Research Centre observed that stigmatising smokers through insults such as "purposeful coughing in their presence" or "glaring looks" can lead them to hide their cigarette-use from family, friends and health-care providers, making them less likely to seek help with quitting.

Interestingly, however, there is evidence that while shaming people for endangering their own health may not work, focusing on how their behaviour affects others can be more effective, suggesting that shocking adverts demonstrating the impact of passive smoking on children may have greater influence than graphic cigarette-packet images of adult smokers dying from cancer. Would focusing on the harm pollution is already causing to individuals – particularly children – be more effective than trying to scare us with dystopian warnings about our post-apocalyptic globally-warmed future?

The shocking death of nine-year-old Londoner Ella Kissi-Debrah from asthma is currently being investigated, but the possibility that it's linked to illegal levels of air pollution is sufficient for the High Court to order a second inquest. "Hopefully if we are successful, national government, local government and individuals have to do something about cleaning up the air," said Ella's mother.

Will this case – allied with recent World Health Organisation research showing that air pollution is a bigger killer than tobacco – shame us out of our cars? That seems unlikely, so long as disapprobation is reserved for governments' failure to accelerate the switch to electric vehicles rather than motorists who fail to modify their own behaviour. To paraphrase Emma Thompson, “Everyone has been asking for clean energy for decades. If we could drive cleanly, we would” appears to be the standard response to what might be termed “korskam” or car shame.

But for all Greta Thunberg and her fellow youth activists' success in shaming governments into declaring climate emergencies, their ambitious targets won't be met unless individuals get behind them, and accept that our own lives must change.

Shame works by deterring people from risking public ignominy. And although fear has its uses (which is presumably why the Extinction Rebellion campaign has doom written into its title), its efficacy is debatable and early HIV/Aids awareness campaigns which deployed tombstones and even (in Australia) the Grim Reaper proved highly contentious.

Could hope be a more effective trigger for change? Open Streets events – such as Edinburgh's recent “car-free Sunday” – take a carrot rather than stick approach by showing what communities can gain from environments in which people can move, play and breathe freely, thus giving everyone an identifiable motive to change their own transportation habits.

In the midst of what governments are finally admitting is a climate emergency, it may seem counter-intuitive to concentrate on our own back yards while the planet burns. But is it as barmy as it sounds? Research published by the Fabian society in 2014 suggests that people who feel engaged with their own neighbourhoods – and empowered to believe they can effect change "in their own back yard" – are more likely to feel inclined to help change the world. Titled Pride Of Place, that report recommended giving local communities more powers to improve their local environments.

Could pride be a more effective game-changer than its opposite? It was certainly deployed effectively by the gay pride movement, which cleverly subverted the once pervasive notion that homosexuality was shameful and while homophobia is far from dead, within progressive societies, it is now frequently exposed over the internet.

Just deserts? Perhaps. But despite advocating the cautious use of well-aimed shame-bombing, Jennifer Jacquet warns we should be wary of becoming “a society of finger-pointers” and instead focus only on “those genuinely doing the most harm to widely held social values”.

We should also, advises Glen Pettigrove, be wary of revelling in the virtuous schadenfreude that comes from watching others being skewered. “I'm really concerned about the ability of communities to forgive their members, as well as the ability of individuals to forgive themselves,” he says, adding that: “One of the best tutors in forgiveness is finding oneself on the receiving end of similar treatment. Because if I discover what it's like to be shamed, I get a different perspective on what was happening to the other individual. Often, we jump to the conclusion that someone is guiltier than they actually are, that their intentions were worse than they actually were, that there were no mitigating circumstances. And that leads to a faulty assessment. We might be right that they shouldn't have acted like this, but we are wrong in thinking that they were really, really bad in acting like this.

“And as social media becomes more familiar, as the inescapability of the histories we create on the internet sinks in and as more people realise their vulnerability to these mechanisms, we might hope that people would be a bit more circumspect.”

Shame, he concludes, has its uses. “We are a social species who flourishes best when we make use of one another to do the good as well as create the beautiful. So maybe if we could sprinkle a certain amount of love in alongside the shame, we'll get the optimum mix.”