When Prince Frederik takes the throne on Sunday, the Danish crown will pass from his mother, Queen Margrethe II, a monarch who has cast doubt on the fact that human pollution is heating the planet, to one who feels bound by duty to call for stronger action on climate breakdown.

“I think it’s important for me to have a message for other people,” he told the Financial Times in 2010 after a trip to the melting Arctic with the heirs to the Norwegian and Swedish thrones, “to convince the broader population there are changes happening and that we are making the change.”

Denmark is not the only country in Europe whose monarchy is using its reach to help people understand the damage done by heating the planet. Norway’s King Harald said in his new year speech that he shared young people’s “concern and impatience” with efforts to protect nature. Sweden’s Crown Princess Victoria attended a climate science conference in 2022 and contributed to a book about exploring Sweden on foot in 2020. Monaco’s Prince Albert, a yacht enthusiast, has for several years pushed efforts to protect oceans through his foundation. In November, Spain’s Queen Letizia talked about “degrowth” as a strategy to meet emissions targets at a seminar on communicating climate.

But among Europe’s monarchs, the most vocal environmentalist is Britain’s King Charles. Since he warned of the dangers of pollution and the cost of cleaning it up more than half a century ago, Charles has gone on to attack corporate lobbyists and climate deniers. “The risk of delay is so enormous that we can’t wait until we are absolutely sure the patient is dying,” he told a meeting of government ministers and businesspeople in 2013.

Some activists have dismissed the rhetoric as hypocritical. Europe’s remaining kings, queens, princes and princesses include some of the richest people on the continent, many of whom lead lavish and polluting lifestyles with the wealth they have inherited. Some own vast tracts of private land – often through the violent conquests of their ancestors – that could be used for the good of society in ways that reduce pressure on nature.

But monarchs also carry widespread support.

“I really think the royals’ commitment to climate and environment, within their limits of course, is seen very positively by most of the population,” said Jean-Pascal van Ypersele, a climate physicist at Université catholique de Louvain in Belgium and the former IPCC vice-chair, who has given private scientific briefings to the royal families of Belgium, Sweden and Monaco.

“The only caveat I would have is around the coherence question,” he added. “Their way of life is very carbon intensive, and more signs of their wish to be coherent would be welcome additions to their speeches.”

Some royals have bucked the trend of flying in private jets and holidaying on superyachts. In doing so, researchers say, they can encourage a much larger group of people to live less polluting lives.

“Elites are role models and have a big influence in setting cultural norms and aspirations,” said Kimberly Nicholas, a sustainability scientist at Lund University in Sweden. “When you see our crown princess in jeans, hiking along a trail you can reach by public transport an hour from your house, it sends the signal that the high life can be low carbon.

“These images plant a seed. Maybe when people are planning their next holiday, they think of a train trip to explore a new part of the country, rather than a flight to an exotic beach.”

Some scientists have suggested royals are also well-placed to reach older and more patriotic audiences. For people who identify with the monarchy but distrust scientists and activists, a king or queen may be a more convincing messenger of the dangers of burning fossil fuels and destroying nature.

Norway’s King Harald, for instance, is a keen fisher, hunter and sailor. He and Queen Sonja have gained a reputation for being outdoorsy hikers who try to care for the environment around them.

Thea Gregersen, a climate psychology researcher at the Norwegian Research Centre, said: “I do think the king might help reach an audience that, for example, Greta Thunberg or the green parties do not reach.”

But monarchs are also bound by informal rules that stop them from taking political stances. While Harald has delivered “safe” messages around protecting the environment, he has shied away from asking tougher questions about the Norwegian oil industry’s role in destroying it.

The king is good at avoiding polarisation, said Gregersen. “The flip side might be that he is not very concrete with regard to the specific actions we need to take to mitigate climate change.”

In Nordic countries that already show widespread political and public support for climate action, the effect of bland messages on the environment may be nearing the limits of what they can achieve.

“The royals seek to avoid divisive issues and not cause political debate,” said Joachim Peter Tilsted, a researcher studying the politics of decarbonisation at Lund University. “Given the consensus-oriented nature of Danish politics and the broad coalition of parties formally backing the Danish climate ambitions and a 2045 net zero target, I doubt that they will push anything that can be regarded as going beyond this sentiment.”