US climate envoy John Kerry and German Foreign Minister Heiko Maas raised the threat of climate change to international security at talks in Berlin on Tuesday.
Mr Kerry is in Germany on the final leg of a week-long Europe trip as preparations for November's Cop26 climate summit in Glasgow gather pace.
With Berlin and Washington seeking to persuade countries to adopt ambitious climate targets before Cop26, Mr Maas and Mr Kerry discussed financing to help developing nations meet those goals and addressed the possible effects of climate change on security.
Mr Kerry said last month that climate change could cause security problems by driving people from their homes and starting refugee crises.
Such conditions could “become a cauldron for extremist organising and proselytising,” he said.
Germany's Foreign Ministry said after Tuesday's talks that the climate crisis "gives a crucial role to foreign policy".
“To achieve our goals, we have to pool our strengths across the Atlantic,” it said.
“We need to convince other global partners to do more to protect the climate, including the major emitters in the G20, but also countries whose economies depend on fossil fuel exports and who are worried about a carbon-neutral future.”
After meeting Mr Kerry on Monday, Armin Laschet, a contender to become Germany's next chancellor, said Europe should create a post that integrates climate and foreign policy.
Mr Laschet will lead Germany's conservatives into September's election, with his party neck-and-neck in the polls with a resurgent Green party.
He said the EU needed a dedicated climate foreign policy.
“We want to revamp Germany into a climate-neutral industrialised country,” Mr Laschet said. “A decade of modernisation is needed to secure jobs and social cohesion.”
EU climate targets unveiled last month envisage a 55 per cent cut in greenhouse gas emissions by 2030, compared to 1990 levels.
Brussels said the target was in line with the 2015 Paris Agreement aimed at keeping the global temperature rise below 2°C.
US President Joe Biden’s climate goals set a 50 to 52 per cent reduction from 2005 levels of greenhouse gas pollution by 2030.
“Europe and the US are leading the way together on climate protection,” German Environment Minister Svenja Schulze said, after meeting Mr Kerry on Monday.
“The new, ambitious climate target in the US and EU will lead to a stronger global dynamic on climate protection.”
Kerry on final leg of Europe trip
Before meeting Mr Maas, Mr Kerry held talks with Kerstin Andreae, the head of an industry body for German water and energy suppliers.
“It is time for a new era in climate diplomacy and international co-operation,” she said, after meeting Mr Kerry at the US Embassy in Berlin.
While in Italy on the first leg of his Europe trip, Mr Kerry sought to offer reassurance that meeting climate targets would not require eating less meat or lowering living standards.
His suggestion that half of the required emissions cuts would be achieved by technology that does not exist caused surprise.
"Look at what we did to push the creation of vaccines, look at what we did to go to the Moon, look at what we did to invent the internet," Mr Kerry told BBC's The Andrew Marr Show.
“We know how to invent and innovate, and we’re going to put every effort we have into making this transition happen as fast as possible.
“I am told by scientists – not by anybody in politics but by scientists – that 50 per cent of the reductions we have to make to get to net zero by 2050 or 2045 … 50 per cent of those reductions are going to come from technologies that we don’t yet have.”
In Britain, which is seeking to position itself as a leader on climate change, Mr Kerry met Cop26 president Alok Sharma for talks on Sunday.
Mr Sharma is lobbying countries to commit to 2030 emissions targets with the aim of reaching net zero by 2050.
The UK’s targets call for a 68 per cent cut by 2030 compared to 1990 levels.
Mr Kerry’s diplomacy in London also looked ahead to June’s G7 summit, to be held in Cornwall, south-west England.
G7 environment ministers are scheduled to meet in an online summit on Thursday and Friday, when Mr Kerry’s diplomacy will continue after he returns to Washington.
The US envoy will take part in that meeting along with Germany’s Ms Schulze and UK Environment Secretary George Eustice.
Mr Kerry met Pope Francis in Italy on Saturday and said the pontiff was a moral leader on climate change.
"The Pope is one of the great voices of reason and a convincing moral authority on the issue of the climate crisis," Mr Kerry told the Vatican’s information portal.
"We need everybody in this fight. All the leaders of the world need to come together and every country needs to do its part.
“I think that his voice will be a very important voice leading up to and through the Glasgow conference, which I believe he intends to attend.”