Former U.S. Vice President Al Gore suggested on Tuesday that the presidency of Donald Trump could end prematurely for "ethical reasons," drawing laughter from a packed movie theater at the European premiere of his latest film on climate change.

"We're only six months into the experiment with Trump. Some experiments are ended early for ethical reasons," Gore said, acknowledging the "provocative" nature of his comment.

Gore said he was convinced that U.S. cities, states and business executives would meet U.S. obligations under the 2015 Paris agreement to fight climate change, despite Trump's decision in June to withdraw from the global pact.

"We have a global agreement and the American people are part of this agreement in spite of Donald Trump," he told hundreds of moviegoers at Berlin's Zoo Palast cinema after a showing of his new film, "An Inconvenient Sequel: Truth to Power."

"We can win this ... All we need is the political will," he said, adding his hope that the United States would "soon once again" have a leader who was committed to halting global warming.

The film argues that fighting climate change is a just, moral battle, on a par with social movements such as the civil rights movement in the United States or the fight for gay rights.

Gore's first documentary, "An Inconvenient Truth," is credited with bringing climate change into mainstream political discourse in the United States a decade ago.

Gore said he was confident the American and German people would remain united in their commitment to reversing the devastating effects of climate change already visible around the world on a daily basis.

He said he was "heartsick" about Trump's decision to pull out of the Paris deal, but said it could trigger an even stronger commitment by other nations to reduce greenhouse gases as an act of defiance.

He lauded Germany's leadership in moving toward alternative energy sources, and said global moves to shift to solar and wind power would drive economic growth and create many new jobs.

The U.S. State Department last week officially informed the United Nations that it would withdraw from the Paris deal, but left the door open to re-engaging if the terms improved for the United States.

But, in a diplomatic cable, U.S. Secretary of State Rex Tillerson told U.S. diplomats to sidestep questions from foreign governments on what it would take for the U.S. government to re-engage in the Paris climate deal, Reuters reported earlier on Tuesday.