Earth is not “some indestructible toy” Prime Minister Boris Johnson told world leaders, as he spoke of the upcoming Glasgow COP26 summit as “the turning point for humanity”.

Mr Johnson addressed the United Nations General Assembly in the early hours of Thursday in a speech in which he conceded a rise in temperatures was inevitable but said we can hope to “restrain that growth”.

The address was the last stop on Mr Johnson’s visit to the United States which has seen discussions held on trade, the Covid-19 pandemic and climate change.

Mr Johnson told the Assembly it was time for “humanity to grow up” and look to the coronavirus pandemic as an example of “gloomy scientists being proved right”.

He added: “The world – this precious blue sphere with its eggshell crust and wisp of an atmosphere – is not some indestructible toy, some bouncy plastic romper room against which we can hurl ourselves to our heart’s content.

“Daily, weekly, we are doing such irreversible damage that long before a million years are up, we will have made this beautiful planet effectively uninhabitable – not just for us but for many other species.

“And that is why the Glasgow COP26 summit is the turning point for humanity.”

The UN summit is being held in Glasgow from late October to early November to “accelerate action towards the goals of the Paris Agreement”, a treaty aimed at keeping the rise in global temperatures to below 2C adopted in 2015.

The speech started with a look at how humanity has been around for around 200,000 years and that the average mammalian species exists for about a million years before it evolves or dies out – suggesting we were, in relative terms, “now sweet 16”.

He said: “We have come to that fateful age when we know roughly how to drive and we know how to unlock the drinks cabinet and to engage in all sorts of activity that is not only potentially embarrassing but also terminal.

“In the words of the Oxford philosopher Toby Ord, ‘we are just old enough to get ourselves into serious trouble’.”

Mr Johnson’s eco focus is a far cry from his past climate-sceptic views.

He admitted on Monday that “if you were to excavate some of my articles from 20 years ago you might find comments I made, obiter dicta, about climate change that weren’t entirely supportive of the current struggle, but the facts change and people change their minds and change their views and that’s very important too”.

Addressing the assembly, he said he was not “one of those environmentalists who takes a moral pleasure in excoriating humanity for its excess” or viewing the green movement as “a pretext for a wholesale assault on capitalism”.

“My friends, the adolescence of humanity is coming to an end,” he said.

“We are approaching that critical turning point, in less than two months, when we must show that we are capable of learning, and maturing, and finally taking responsibility for the destruction we are inflicting, not just upon our planet but ourselves.”

He called on countries to cut their carbon emissions by 68% by 2030 compared with 1990 levels, praised the end of China’s international financing of coal, and congratulated Pakistan’s pledge to plant 10 billion trees.

The 20-minute speech ended with references to renowned Greek writer Sophocles and a Muppet.

On Jim Henson’s creation, he said Kermit was wrong when he sang It’s Not Easy Bein’ Green, adding it was “easy, lucrative and right” to be green.

He added: “Sophocles is often quoted as saying that there are many terrifying things in the world, but none is more terrifying than mankind, and it is certainly true that … we are uniquely capable of our own destruction, and the destruction of everything around us.

“But if you look at the Greek, Sophocles actually said … was that man is deinos and terrifying isn’t quite right as far as a translation for deinos. What Sophocles really means is humanity is awesome – both terrifying but also awesome.

“We have an awesome power to change things and to change things for the better, and an awesome power to save ourselves.

“In the next 40 days, we have to choose, the world has to choose what kind of awesome we’re going to be.”