Pope Francis has made climate change a central pillar of his papacy, writing a nearly 200 page encyclical (a letter from a pope to all Catholic bishops) about the importance of taking action to protect the planet — and using Twitter to express his outrage over what is being done to the environment.

President Donald Trump, on the other hand, has consistently denied the impact of humans on the earth's climate, calling the theory of climate change "bullshit," "an expensive hoax," and something "created by and for the Chinese."

When Pope Francis and President Trump met in Rome on Wednesday, some expected it could get awkward.

Instead, the get-together was a mostly cordial, if slightly strained, affair. The two met behind closed doors for 30 minutes, posed for photos (one of which, featuring a grinning Trump flanked by a dour Francis, became instant meme fodder), and made small talk. They also exchanged gifts, an occasion that brought the pope's concern over climate change to the forefront.

Francis gave Trump a set of three encyclicals: one on practicing inclusion and forgiveness in families; another on the joy of reading the Gospel; and his climate chance encyclical, “Laudato Si."

While presenting foreign leaders with writings is a papal tradition, most observers believed Francis giving a climate change skeptic a 200 page letter about the importance of fighting climate change was no accident. Francis introduced it to Trump using its English name, referring to the subject as the "care of our common home, the environment.” 

A senior Vatican leader told The Washington Post that the gift was a "message," while a newspaper columnist in Rome called it a "politically loaded" gesture that affirmed the Vatican's stance on the U.S. not leaving the Paris Climate Accord, which Trump has threatened to do. 

If Francis was indeed sending a message, it looks like it was received — if not by Trump, then by other politicians. Secretary of State Rex Tillerson claimed the discussion between Francis and Trump on climate was "a good exchange," and Senate Minority Leader Chuck Schumer said Trump needed to read the letter to understand how important it was for the U.S. to stay in the Paris agreement.

Whether or not Trump will actually read "Laudato Si" remains to be seen, though he said that he would and ended the meeting by telling the Pope: "I won't forget what you said."