As King Charles III begins his reign as Britain's new monarch, focus turns to how he may use his position as head of state to promote causes that he's been passionate about for decades — the environment and climate change, in particular, as well as other philanthropic efforts.

Throughout her 70 years on the throne and up until her death on Thursday, as monarch, Queen Elizabeth II sought to maintain strict political neutrality, going so far as not to vote.

And while Charles has been careful not to tread too publicly, he does have a history of wading into politics, something over which some British officials have voiced concern that he may be more willing to do as king.

Climate change has long been a focus for Charles

Nowhere has Charles been more outspoken than the threat posed by climate change. Last year, speaking at the opening ceremony of the COP26 climate summit in Glasgow, Scotland, he warned that the time for addressing climate change had "quite literally run out."

In order to tackle the problem, he said, "We have to put ourselves on what might be called a war-like footing."

For Charles, a passion for the environment dates back decades. In an interview posted to the Royal Family's website in 2020, he recalled how as a teenager he began to feel increasingly alarmed by "the destruction of everything ... all this sort of white heat of progress and technology to the exclusion of nature and our surroundings, and also this complete determination to defeat nature and to suppress everything to do with it."

"I seem to remember minding an awful lot about it," he said.

Charles has reportedly not been shy about promoting his views on the environment, among other topics, in private letters to government ministers dubbed "black spider memos," an apparent reference to his scrawled handwriting. The letters addressed everything from the U.K.'s involvement in the war in Iraq to the availability of herbal alternative medicines.

In the 1980s, Charles, then the Prince of Wales, also famously clashed with the "Iron Lady" herself — former Prime Minister Margaret Thatcher — who reportedly pushed back on his efforts to influence her government's policies around urban renewal.

Thatcher rebuffed his efforts to get her to meet with leaders from a community program that Charles helped found. Author Howard Hodgson, writing in his biography Charles – The Man Who Will Be King, said Thatcher "believed that this would obviously provide her opponents with the valuable point that the Prince of Wales, although supposed to be politically neutral, was in fact opposed to Thatcher and her uncaring policies," according to Express.

He has also been vocal about immigration policy

Earlier this year, Charles was seen as making a thinly veiled criticism of a controversial new immigration policy from the government of former Prime Minister Boris Johnson that sends all asylum seekers to Rwanda for processing. In his Easter message in April, Charles referred to the "unutterable tragedy" of those who've been "forced to flee their country and seek shelter far from home," saying they are "in need of a welcome, of rest, and of kindness." In private, he reportedly described the policy as "appalling."

One unnamed senior Cabinet official quoted by The Sunday Times said: "Prince Charles is an adornment to our public life, but that will cease to be charming if he attempts to behave the same way when he is king. That will present serious constitutional issues."

In response to the controversy, representatives for the prince issued a statement reiterating that as monarch, Charles would remain "politically neutral."

One cause that Charles may be able to promote without straying too far from neutrality is the Prince's Trust, which he founded in 1976. According to Vanity Fair, the trust reportedly pioneered the concept of micro-credit — small loans that have been used to help more than 50,000 disadvantaged youths to start their own business.

His actions will be closely watched

Whichever direction he goes, the king's actions will be closely followed, and are all but assured to invite comparisons to the record established by Queen Elizabeth. Following the asylum policy kerfuffle earlier this year, Michael Cole, a former royal correspondent for the BBC, said in an interview that as king, Charles will need to be "careful" with voicing political opinions.

"[The] Queen has never put a foot wrong in this way," he said.

"He must take great care and perhaps he ought to have around him," Cole said, "people who actually see these tiger traps and makes sure he walks around them and not straight into them."

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