"Protecting the climate matters to all of us," said Merkel, whose country will host a G20 summit and UN climate talks this year.
"We all feel the impacts of climate change... We are responsible for each other, we are liable for each other, we share a common destiny."
Urging the international community to maintain "the spirit of Paris" - the 196-nation climate pact reached in late 2015 - she said: "I am still trying to convince the doubters."
She was speaking at the annual informal "Petersberg Climate Dialogue" talks hosted by Germany, with some 30 nations taking part.
At the talks in Berlin, Germany's Environment Minister Barbara Hendricks and Chinese Special Climate Envoy Xie Zhenhua jointly urged the United States to stay in the Paris Climate Agreement.
Trump on the campaign trail dismissed climate change a "hoax" perpetrated by China and vowed to "cancel" the international pact to curb emissions from burning oil, coal and gas.
He has not yet executed his threat, but has appointed an anti-climate litigator to lead the Environmental Protection Agency, and chosen the former CEO of oil giant ExxonMobil, Rex Tillerson, as his secretary of state.
'Elephant in room'
Merkel said the "energy transition" in Germany - away from nuclear power and fossil fuels and toward solar, wind and other renewables - proved that "prosperity and sustainability can go hand-in-hand".
"About one third of the electricity we consume in Germany comes from renewable energy, and despite the rapid growth we have maintained a stable supply," said the former environment minister.
She said efficiency gains now meant giant projects such as off-shore wind farms could be built without state subsidies, but she admitted there were new "bottlenecks", mainly in transporting and storing green energy.
Worldwide, Merkel said, China was now the leader in renewables, India was planning 50 new solar parks, while nations from the United Arab Emirates to Morocco and Kenya were building green power megaprojects.
Trump will meet other leaders of the G7 wealthy nations in Sicily, Italy on May 26th-27th before Merkel hosts a G20 meeting in the northern port city of Hamburg on July 7th-8th.
The next global meeting on the UN Convention on Climate Change will be organized by the Pacific island state of Fiji, but hosted by the German city of Bonn on November 6th-17th.
"We must all do more to build green economies" Fiji's Prime Minister Voreqe Bainimarama said in Berlin, and urged that the "transformation we need to make must be accelerated".
He pointed to "the challenge that the new administration in the US presents to the multilateral consensus on the need for climate action," calling the issue "the elephant in the room" for climate negotiators.
By Frank Zeller, AFP