Prince Charles, a lifelong environmentalist who has championed organic gardening and runs one of his cars on white wine and cheese, has urged world leaders to turn talk into action at the upcoming UN climate summit.
Queen Elizabeth II's eldest son and heir, 72, is due to attend events at the two-week COP26 summit in Glasgow starting on October 31, along with his 95-year-old mother.
But in an interview with the BBC broadcast on Monday, he said he worried that world leaders would "just talk", adding: "The problem is to get action on the ground."
The UN summit will try to persuade major developing economies to do more to cut their carbon emissions, and get the rich world to cough up billions more dollars to help poorer countries adapt to climate change.
When asked if Prime Minister Boris Johnson's UK government was doing enough itself against climate change, Charles replied: "I couldn't possibly comment."
The Prince of Wales expressed sympathy with climate protesters, who have been blocking roads in Britain for several weeks as part of a campaign to make homes more environmentally efficient.
"I totally understand the frustration," he said, as the government tries to get tough with the demonstrators, who have caused gridlock to rush-hour traffic with sit-down protests and by glueing themselves to tarmac.
"All these young people feel nothing is ever happening so of course, they're going to get frustrated," he added, stressing: "But it isn't helpful, I don't think, to do it in a way that alienates people.
"So I totally understand the frustration, the difficulty is how do you direct that frustration in a way that is more constructive rather than destructive."
Charles, whose Highgrove estate in western England has an entirely organic garden and farm, also outlined some of his own actions to reduce his carbon footprint, including cutting down on meat and fish.
In 2008, his office revealed he had converted an Aston Martin car he owns to run on biofuel made from surplus English white wine and whey from cheese manufacturing.
Other cars in his fleet had been adapted to run on biodiesel made from used cooking oil, as a way to reduce his carbon footprint.