Greta Thunberg needs to get a grip.

The celebrity teen climate activist addressed the UN and accused the assembled worthies of coming “to us young people for hope. How dare you! You have stolen my dreams and my childhood with your empty words.”

Someone may have stolen her childhood, but the guilty parties can’t be found at Turtle Bay. A 16-year-old from Sweden, Thunberg thundered, “I should be back at school on the other side of the ocean,” which would have been easy enough to achieve, beginning with not taking two weeks to sail across the Atlantic last month in a jet travel-eschewing publicity stunt.

Thunberg is the leading edge of a youth movement against climate change — including a global climate strike last week — that is being promoted and celebrated by adults who find it useful for their own purposes.

Kids are powerful pawns. The catchphrase “for the children” has a seductive political appeal, while kids offer their adult supporters a handy two-step. The same people who say, “The world must heed this 16-year-old girl” will turn around and say to anyone who pushes back, “How dare you criticize a 16-year-old girl?” (I can feel the tweets filling up my mentions right now).

There’s a reason that we don’t look for teenagers for guidance on fraught issues of policy. With very rare exceptions — think, say, the philosopher John Stuart Mill, who was a child prodigy — kids have nothing interesting to say to us. They just repeat back what they’ve been told by adults, almost always with less nuance and maturity.

Much of the climate advocacy of young people boils down to the plaint that all parents everywhere are all too familiar with: “I want it, and I want it now.” As one headline on a National Geographic story put it, “Kids’ world climate strikes demand that warming stop, fast.”

Behind the foot-stomping is the idea that a long-running global phenomenon can be quickly stopped, if only adults cared as much as the kids demanding action. This fails to account for such recalcitrant factors as costs and complexity, but when do children ever think of those? (And who can blame them? They’re children.)

Instead, the youthful climate activists claim they’ve been sold out by their elders. Thunberg put it with her usual accusatory starkness at the United Nations: “You are failing us, but young people are starting to understand your betrayal.”

This is laughable. By no broad, global measure of social and economic well-being have we failed kids. The global poverty rate fell from 28% in 1999 to 11% in 2013, according to Human­Prog­ress.org. Life expectancy around the world increased from 63.2 years to 71.9 years from 1981 to 2015. The infant mortality rate dropped from 64.8 per 1,000 live births in 1990 to 30.5 in 2016. The completion rate for primary school increased from 80% in 1981 to 90% in 2015. The same benign trends hold for hunger, child labor, literacy and so on.

Today’s youth are entering adulthood in a world that is wealthier, healthier and better-educated and -fed than ever before. If climate change proves a significant challenge, they will have more ­resources and technology to grapple with it than any other generation in the history of mankind.

Of course, they aren’t aware of any of this because the adults they listen to don’t tell them. Instead, they feed the kids a diet of apocalyptic warnings that children repeat back as if they are urgent insights. One speaker at the youth climate rally in DC last week said we have just 18 months — yes, only until the beginning of 2021 — to forestall irreparable environmental harms.

According to National Geographic, “more than a few teens who began as fervent activists have dropped out, citing depression, anxiety and other fears that the world’s leaders will not act in time to prevent their lives — and the lives of their children — from being irretrievably altered by climate change.”

This is nuts, and it’s the adult enablers who are ultimately responsible. As for the kids, they’ll be alright. One day, they will grow up, even in a warming world.

Twitter: @RichLowry