Boris Johnson hailed G7 commitments to tackle climate change, but admitted “I’m not going to pretend that our work is done”.
The leaders gathered at the summit in Cornwall committed to support a “green revolution” that creates jobs, cuts emissions and seeks to limit the rise in global temperatures to 1.5 degrees centigrade.
They also promised to increase the amount of climate finance on offer to developing countries.
Rich countries pledged more than a decade ago to provide 100 billion US dollars (£70 billion) a year by 2020 in additional finance to poorer nations to develop cleanly and cope with the impacts of climate change, but are around 20 billion US dollars (£14 billion) short of the goal.
The Prime Minister told reporters at the close-of-summit press conference: “I’m not saying it’s going to be easy. It’s a lot of money still to raise but don’t forget the UK has put in £11.6 billion, we’ve had a big pledge from Canada, we’ve had big pledges around the table.
“I do think we can get there and I think it’s vital that we do.”
The UK hosts the United Nations Cop26 climate summit in November and Mr Johnson said the promises made at the G7 were “very good start”.
Mr Johnson said: “Later this year the UK will host the Cop26 Summit, which will galvanise global action on fighting climate change and create a healthy planet for our children and grandchildren.
“G7 countries account for 20% of global carbon emissions, and we were clear this weekend that action has to start with us.”
The leaders were addressed by television naturalist Sir David Attenborough, who stressed the importance of the issue.
He said the scientific response to the Covid-19 pandemic had demonstrated what was possible when there was a “clear and urgent” goal.
But the fight against climate change was as much a “political and communications” challenge as a scientific one, he said in a video address.
Sir David told the leaders gathered in Carbis Bay: “The scientific collaboration on Covid treatment and vaccines showed just how much we can achieve together when the goal is clear and urgent.
“We know in detail what is happening to our planet. And we know all of the things we need to do during this decade.
“Tackling climate change is now as much a political and communications challenge as it is a scientific or technological one.
“We have the skills to address it in time. All we need is the global will to do so.”
Mr Johnson also launched a £500 million “blue planet fund” to protect the world’s oceans and marine life.
Mixed in with the environmental intentions of the G7 is an attempt to reassert the values of the world’s leading democracies.
The “build back better for the world” plan will bring together G7 countries to develop an offer for high-quality financing for vital infrastructure, from railways in Africa to wind farms in Asia.
The move is part of an attempt to counter Beijing’s “belt and road” initiative which has spread Chinese influence around the globe.
The new approach is intended to give developing countries access to more, better and faster finance, while accelerating the global shift to renewable energy and sustainable technology.