Boris Johnson admitted he fears the major international climate change summit he will host from Sunday could fail to make the progress needed.
The Prime Minister will welcome world leaders to Glasgow for the United Nations Cop26 summit but said it was “touch and go” whether key goals would be met.
“We need as many people as possible to go to net zero so that they are not producing too much carbon dioxide by the middle of the century,” he said.
“Now, I think it can be done. It’s going to be very, very tough, this summit.
“And I’m very worried, because it might go wrong and we might not get the agreements that we need.
“It’s touch and go.”
Mr Johnson said “peer pressure” at the UN summit could force some nations into action.
But with some major world leaders including China’s Xi Jinping expected to stay away due to the state of the coronavirus pandemic the chances of that tactic being a success may be limited.
Mr Johnson acknowledged “it’s very, very far from clear that we will get the progress that we need” although he praised Australia for the “heroic” decision to commit to net zero by 2050.
Downing Street said Mr Johnson was setting out the “realistic situation” about the chances of Cop26 being a success.
The Prime Minister’s official spokesman said: “We have made some progress with a number of countries, Saudi Arabia has come forward with some commitments, for example.
“But the Prime Minister was simply setting out the realistic situation that bringing together countries from around the world to sign up to ambitious targets such as these that require tangible commitments is difficult and challenging, and will require some intense negotiation.”
The Prime Minister, who was questioned by schoolchildren in Downing Street, hit out at Coca-Cola as being one of 12 corporations “producing the overwhelming bulk of the world’s plastics”.
He told a children’s press conference on the climate crisis: “There are about 12 companies at the moment, 12 big corporations, that are producing the overwhelming bulk of the world’s plastics.
“Big famous drinks companies that you may know but I won’t name. I don’t know why not, but I won’t name them.”
Having said he would not name any of the firms, he then continued: “Coca-Cola, for instance, and others, which are responsible for producing huge quantities of plastic, and we’ve got to move away from that and we’ve got to find other ways of packaging and selling our stuff.”
Mr Johnson said recycling plastic “doesn’t work” as he stressed the need to reduce the amount of the material that is used.
During a press conference at No 10 he said: “Recycling isn’t the answer. Recycling… it doesn’t begin to address the problem.”
He said “the only answer” was “we’ve all got to cut down on our use of plastic”.
Appearing alongside Mr Johnson, WWF UK’s chief executive Tanya Steele said: “We have to reduce, we have to reuse – I do think we need to do a little bit of recycling, PM, and have some system to do so.”
But Mr Johnson replied: “It doesn’t work.”
In response to the Prime Minister, Recycling Association chief executive Simon Ellin told BBC Radio 4’s World At One programme: “It’s very disappointing. I think he has completely lost the plastic plot here, if I’m honest.”
Coca-Cola said it was making “steady progress” in efforts to cut waste and all its smaller bottles in Great Britain were made from 100% recycled plastic.
A Coca-Cola company spokesman said: “As the world’s biggest beverage company, we have a responsibility to help solve it.
“We believe circular recycling solutions are imperative in creating a path to keep plastic out of our natural environments for good.
“We don’t want to see any of our packaging end up where it shouldn’t which is why we aim to collect and recycle a bottle or can — regardless of where it comes from — for every one we sell by 2030 globally.”
During the questioning in Downing Street, Mr Johnson also said he does not “want to support new coal mines”, as ministers face pressure to prevent a site opening in Cumbria.
The Prime Minister’s spokesman said Mr Johnson was “talking in broader terms about our stated aim to phase out the use of coal in the long term” and there were “specific reviews into individual applications that pre-date that”.