John Marsden has spent decades writing about, teaching and founding schools for young people – and lately, he has been getting worried. Really worried.

In his new book about how we treat and understand children, Marsden – the author best known for his Tomorrow, When The War Began series – is in no mood for niceties about contemporary parenting. “We are seeing an epidemic of damaging parenting at the moment,” he writes.

In The Art of Growing Up, billed as a manifesto, Marsden writes of the problematic state of parents being in love with their children, rather than loving them. He warns of parents playing eternal advocate for children who may not be as gifted or guileless as adults may like to imagine. He despairs at “curling parents” – the Scandinavian term for those who furiously clear all paths for their children. “Toxic parenting,” he writes, is having serious impacts.

But are we engaged in “toxic parenting” en masse? Or is it just a case of extremes worsening?

“No, I think this is a widespread problem,” Marsden says. “Damaging parenting,” he says, is not equivalent to emotional abuse, but rather represents an “ill-conceived and misguided” approach that is doing significant emotional damage.

“It’s mostly the middle class that I’m referring to. It’s not that people are setting out to act destructively, but their common sense and instincts seem to have been overridden by other considerations. The emotional damage is coming from an anxiety which often approaches panic.”

In the last five years, he says, it has become more difficult to run a school (he is principal and founder of two). And The Art of Growing Up does, at times, read much like the work of a principal who is fed up.

Marsden says that this contemporary crop of teenagers is outperforming generations past in terms of academic achievement, political engagement and so on – but he is fearful about their emotional health, borne out by statistics on the prevalence of mental health issues among the young.

“The scale of the problem is massive. The issue of emotional damage is pandemic,” he tells the Guardian. “The level of anxiety is something I’ve never seen before, and I don’t know how it can be improved.”

Marsden says that much of the anxiety among parents and children springs from concern that the world is a dangerous place, with traditional “safe” authority figures no longer to be trusted. That, coupled with an infantilisation of children as pure, helpless creatures, leads parents to cosset and fret over their offspring, and demand much of the same from educational institutions.

“Part of that is a fear, in particular, of physical injury,” he says. “Of course, all reasonable parents are concerned about physical injury to a child, but if that overrides everything else then what you have instead is a kind of slow death by emotional damage which is so awful to witness.”

Marsden runs two private schools in Victoria, both housed on extensive bushland campuses. Children climb trees, ride bikes, camp and don’t wear uniforms. They are expensive schools to attend but Marsden believes all schools can address the “boring”, “antiseptic” lives of contemporary children and young people, lives which are lived primarily through second-hand experiences, he says, and devoid of grazed knees.

“It’s ironic that in Australia, which has more free space than about anywhere in the world, children are put into school campuses which have recreation areas the size of a few basketball courts. And the rules are: you’re not allowed to run, you’re not allowed to touch other people, you’re not allowed to share food … you certainly can’t pick up a stick, you certainly can’t climb a tree.” He is incredulous.

By limiting children’s exposure to danger, to fear, we are limiting their ability to mature, develop resilience and independence, he says. Marsden despairs at parents who don’t allow four-year-olds to peel their own mandarins. “They’re capable of helping themselves and we have to be forceful in making sure we step back.”

And from the grace of childhood, so venerated by society, children inevitably fall when they become adolescents, demonised by finger-wagging elders. The feelings and experiences of these young people are too often trivialised, he says, while we constantly worry over exposure to sugar, screens and cyberbullies.

Marsden doesn’t like to think in terms of optimism or pessimism. It’s a bit of a cop-out, relinquishing the optimist of the obligation to make the world better. And while he has no hesitation in labelling various parts of today’s parenting and childhood culture at crisis levels – attitudes and behaviours which can be linked to tragedies ranging from addiction to domestic violence – he won’t be drawn on whether what is happening today is more toxic than what has happened in the past.

“We’re failing them in different ways,” he says. And, for Marsden, that’s not just good enough.

• The Art of Growing Up by John Marsden is out 23 July

• This article was amended on 17 September 2019 because an earlier version misnamed John Marsden’s series Tomorrow, When The War Began, as Tomorrow, When The World Began. This has been corrected.