A longstanding advocate for environmental and climate issues — King Charles III — now heads the 56-member Commonwealth of Nations, an international organization of mostly former British colonies that spans a third of humanity.
Charles, officially proclaimed the new monarch of the United Kingdom on Saturday, has long been outspoken on climate change, deforestation and pollution — and he has used his position to push for fulfilling the 2015 Paris Agreement, which obliges virtually all of the world's nations to prevent average global temperatures from rising more than 2 degrees Celsius above pre-industrial levels, or 1.5 degrees C. if possible.
The Commonwealth's secretary-general, Baroness Patricia Scotland, said "the growth and vibrancy of our modern Commonwealth" is a credit to Charles' mother, the late Queen Elizabeth II. The Commonwealth says it works to help member countries "protect their environments and use their natural resources sustainably."
On the environment and climate, his views line up with those of United Nations Secretary-General Guterres, who recently said the Paris treaty's 1.5 degree goal is on "life support" now that the planet has warmed by more than 1 degree.
It is less clear how much of a difference Charles' advocacy might make on the world stage, however, since his powers are largely ceremonial and the London-based Commonwealth is seen by some as a largely post-colonial association with little real influence.
He also foresaw having to cut back on his work for "charities and issues," and, as a frequent globetrotter and member of a royal family with vast wealth, he has not always matched his worldly views with his personal actions.
Time for 'a war-like footing' on climate
Charles has been speaking out on environmental issues since at least 1970, and in more recent years he used his position to call for a range of improvements such as greener business models, cleaner energy sources and more organic farming.
Last year he told the BBC he has adapted his diet and home energy sources, and his retrofitted Aston Martin, which he's had for 51 years, "runs on, can you believe this, surplus English white wine and whey from the cheese process.”
He bought a home in Scotland and, in 1985, converted the Duchy Home Farm into an organic system that he also uses to teach children about soil health. Charles turned the Duchy of Cornwall estate into an inheritance for Prince William valued at £1 billion (US$1.2 billion) at the end of March. It has provided Charles with a yearly income of more than £20 million (US$23 million) from the estate.
He put solar panels on his London mansion and country home, but he has fought against installing wind turbines on his properties. His constellation of residences and staff consume far more energy and resources than the average household, and he has long used a private jet to fly around the world.
As monarch, Charles can claim to speak for some 2.5 billion people who live in the Commonwealth, mostly in Africa, Asia, the Americas, and the Pacific. In his first speech to the nation on Friday evening since the death of his mother, Charles acknowledged he would have less time for activism.
"It will no longer be possible for me to give so much of my time and energies to the charities and issues for which I care so deeply," he said in a televised address. "But I know this important work will go on in the trusted hands of others.”
He formally took the throne when the U.K.'s Accession Council of senior government and church officials confirmed his succession from his late mother after she died at the age of 96 on Thursday. She reigned for more than 70 years, the longest of any British monarch.
Last year, then-Prince Charles cited the overwhelming scientific evidence behind human-caused global warming as he told the U.N. climate summit in Glasgow, Scotland, that "time has run out" for urgent, concrete actions to address the dire threat to our planet's health.
"The Covid-19 pandemic has shown us just how devastating a global, cross-border threat can be," he said. "Climate change and biodiversity loss are no different — in fact, they pose an even greater existential threat, to the extent that we have to put ourselves on what might be called a war-like footing."