Two years of school strikes had spurred political commitments and “big speeches” but “the climate and ecological crisis has never once been treated as a crisis,” Thunberg and three other youth climate activists wrote in The Guardian.

“The gap between what we need to do and what’s actually being done is widening by the minute,” they wrote. “Effectively, we have lost another two crucial years to political inaction.”

Thunberg said the group planned to tell Merkel “she must face up to the climate emergency – especially as Germany now holds the presidency of the European Council.”

“Europe has a responsibility to act,” they wrote, noting that EU nations and Britain were responsible for an estimated 22 per cent of “historic accumulative global emissions.”

“It is immoral that the countries that have done the least to cause the problem are suffering first and worst,” the activists said.

They said they would hand Merkel an open letter signed by 125,000 people demanding that EU leaders “stop pretending that we can solve the climate and ecological crisis without treating it as a crisis.”

The letter urges governments to halt all investments in fossil fuel exploration and extraction, end subsidies and “immediately and completely divest from fossil fuels.”