Whatever else happens on President Donald Trump’s state visit to the U.K., one of the more fraught meetings might end up being his Monday afternoon tea with heir to the British throne, Prince Charles.

While smiles and pleasantries were in abundance, the two men have vastly different stances on the environment.

For over 40 years, the Prince of Wales has been outspoken about a number of environmental issues facing the planet.

Meanwhile, President Trump has previously publicly accused climate experts of having a “political agenda.” And, before taking office, he called the concept of human-caused warming “a con job” and a “hoax.”

Whether the two actually engaged in any kind of environmental talk during their meeting is unclear. But many media outlets in the U.K. speculated about just how uncomfortable the encounter might get, considering Trump would not be likely to stay quiet if the issue were brought up.

President Trump’s administration has been accused of downplaying the threat of climate change and questioning the science behind it.

The president famously pulled the United States out of the 2015 Paris Climate accord meant to curb emissions that cause climate change, saying it was too costly for the American people and brought few tangible gains.

Last year, the Trump administration was also accused of scrubbing information on climate change from U.S. government websites.

He has bragged about the U.S.’s status as the No. 1 producer of oil and natural gas in the world, even tweeting the day before his arrival in the U.K. that “we’re shipping freedom and opportunity abroad” after the first shipment of liquefied natural gas left a Louisiana terminal. He has also vowed to bring more coal mining jobs back.

Trump has also cast doubt on last year’s report by his own government on the projected devastating economic impact of climate change in the United States.

Asked about the findings, he said, "I don't believe it."

In stark contrast, Prince Charles, 70, has championed sustainability for decades in speeches, articles, books and films.

He has consistently used his clout to raise awareness around issues like climate change, deforestation and ocean pollution.

His Rainforest Project, launched in 2007, has been trying to tackle tropical deforestation that scientists say contributes to climate change.

In 2017, he delivered a landmark speech in Malta about conserving the ocean and the circular economy.

More recently on a tour of the Caribbean this year, he has talked about “potentially catastrophic global warming,” praising the younger generation for raising their voices against climate change threatening their future.

“When he talks about environment he talks about wanting world to be a better place for his grandchildren and wanting world to be preserved for them,” Caroline Harris, a royal author, told NBC News.

His official website says the prince has received numerous awards for his environmental work while trying to live a more sustainable lifestyle himself.

Prince Charles, Prince of Wales plants a tree during his visit to the Botanical Gardens during a visit to St. Vincent and the Grenadines on March 20, 2019 in Kingstown. Phil Noble / Getty Images file

Traditionally senior royal family figures stay out of politics, but Charles has been known to walk a fine line. In 2015, letters he wrote to government ministers, which included missives on the environment, became public.

A source close to Charles said it was "very likely” climate change would be discussed, a British tabloid reported last month.

Whether the prince stayed diplomatic and avoided mentioning environmental issues during the Monday afternoon meeting in Clarence House, it looks like President Trump will not be able to avoid the topic of environment during his time in the U.K.

Outgoing Prime Minister Theresa May is expected to raise the issue of climate change with the American president, Downing Street told BBC News Monday.

May has been asked by 250 U.K. climate researchers to "robustly challenge" the president about his “reckless approach to climate change” during his visit.

The experts also said that honoring Trump with a state visit was “incompatible” with the U.K.’s global leadership on climate change.

Prince Charles chats with Donald Trump and his wife Melania Trump during the Museum of Modern Art reception on the first day of the royal eight-day visit to the U.S., on Nov. 1, 2005 in New York City. Chris Jackson / Getty Images file

In contrast to recent U.S. actions surrounding climate change, the British Parliament declared a climate change emergency last month. The country also plans to reduce its greenhouse gas emissions by at least 80 percent by 2050.

But despite the two countries’ differences, the state visit will still fete Trump and the U.S. by extension. As the U.K. negotiates its divorce from the Europe Union, British officials are eager to show that their "special relationship" with the United States is as strong as ever.

A few high-profile U.K. figures, however, have turned down an opportunity to meet with the American president, including opposition leader Jeremy Corbyn who said Prime Minister May should not be rolling out the red carpet for a state visit to honor a president who, among other things, “backs climate change denial”.

London Mayor Sadiq Khan, with whom Trump has traded barbs for years, also criticized the state visit in an article over the weekend, arguing that Trump is seen as a figurehead of the global far-right movement.

Protesters are also expected to take to the streets of London during the president’s visit, although Trump tweeted Monday that he had not seen any.

London part of trip is going really well. The Queen and the entire Royal family have been fantastic. The relationship with the United Kingdom is very strong. Tremendous crowds of well wishers and people that love our Country. Haven’t seen any protests yet, but I’m sure the.... — Donald J. Trump (@realDonaldTrump) June 3, 2019