Boris Johnson has said he hopes the Cop26 climate summit will hammer out the final details of “an era-defining outcome” for the planet and future generations.

The Prime Minister told the 12th Petersberg Climate Dialogue that the stakes are too high for the talks in Glasgow in November to be a last minute dash for the line, and countries should spend the next six months working on the issues.

He said climate action will be at the heart of the G7 leaders’ summit in Cornwall next month, calling on the world’s most developed economies to provide finance for poor countries to cope with global warming.

He told the online event convened by German Chancellor Angela Merkel: “This will be the decade in which we either rise up and tackle climate change together or else we sink together into the mire.

“And this year at Cop26 will be the moment the world chooses which of these two fates awaits us.”

Mr Johnson urged countries to spend the six months up to the talks “untangling the knots and unblocking some of the stickiest issues” on climate change.

“If we do the hard miles now, I hope that in November we can meet in person in Glasgow to hammer out the final details of what must be an era-defining outcome for our planet and for future generations,” he said.

He said the G7 summit will be the first where every member has committed to cutting emissions to net-zero by 2050, before congratulating Ms Merkel on announcing Germany’s new goal to reach net-zero by 2045.

Ms Merkel has set out plans for a stronger target to cut emissions by 65% on 1990 levels, up from 55%, and bring its net-zero target forward from 2050 to 2045, following a court ruling that Germany’s 2019 climate law is insufficient.

The move makes Germany the latest country to raise its ambition for cutting emissions in the run-up to the Cop26 summit.

Reaching net-zero emissions – which is needed to stop temperatures rising to dangerous levels – requires cutting pollution to as close to zero as possible and then taking steps such as planting trees to absorb the remainder.

Mr Johnson said that at the G7 meeting, he will be seeking commitments from leaders to support the transition to net-zero, kickstart a green industrial revolution and build climate-resilient economies.

He also said: “I hope to secure a substantial pile of cash to help all countries to do that.

“We simply must meet our existing commitments on climate finance – that long-overdue 100 billion (US) dollars a year target, and then we must go further still.

“Developed nations can’t stop climate change on their own but if we want others to leapfrog the dirty technology that did so much for us, we have a moral and practical obligation to help them to do so.”

He added “that means putting our money where our mouth is”, pointing to the UK’s recent doubling of its climate finance contribution, and saying he would bend the ear of fellow leaders to do the same.

Greenpeace UK’s head of politics Rebecca Newsom said: “The Prime Minister is absolutely right to prioritise pushing G7 members to ramp up their international climate finance commitments to meet promises made on this issue over a decade ago.

“But despite his call for leaders to put their money where their mouth is, Boris Johnson has undermined his own message through the decision to cut international aid. These cuts should be reversed immediately, with confirmation that the UK’s contribution to climate finance is additional to the aid budget.

“It’s not just our diplomatic credibility at stake, but the lives of millions of people on the front line of a crisis they did little to create.”

United Nations Secretary-General Antonio Guterres warned that the success of Cop26 rests on achieving a breakthrough on finance and helping countries adapt to the impacts of climate change.

“Developed countries must honour their long-standing promise to provide 100 billion US dollars annually for climate action in developing countries,” he said, adding the G7 summit is a pivotal moment.

“I call on the leaders of the G7 to take the lead, with other developed countries following, to make substantial climate finance pledges for the coming five years.

“For some, this means at least doubling their latest climate commitments.”

He said countries must make the six months until Cop26 count, urging ministers to start working on an ambitious and balanced political deal and for all countries to make sure their climate plans are ambitious, credible and verifiable.