They seem like an unlikely pair, but Pope Francis and Leonardo DiCaprio have joined forces, brought together by their shared passion for the environment.

According to a report from Fox News Latino, the actor visited Pope Francis at the Vatican to discuss concerns over environmental issues. DiCaprio made it a point to greet the pope in Italian when he dropped by the Apostolic Palace.

"Your Holiness, thank you for granting me this private audience with you," he said in Italian before kissing the pope's ring, a gesture of respect to the head of the Catholic Church.

In his meeting, DiCaprio gifted him with a book of works by the 15th-century Dutch painter Hieronymus Bosch. In particular, the actor pointed out the reproduction of Bosch's "Garden of Earthly Delights" that his family had when he was younger.

"As a child I didn't quite understand what it all meant, but through my child's eyes it represented a planet, the utopia we had been given, the overpopulation, excesses, and the third panel we see a blackened sky that represents so much to me of what's going in in the environment," DiCaprio said, adding that the painting also illustrated Francis' environmental concerns.

The actor also donated a check for charity works of the pope's choosing, while Francis gave the actor a leather-bound copy of his encyclical "Laudato Si: On Care for Our Common Home" and the earlier "The Joy of the Gospel".

Pope Francis is known for being an advocate of protecting the environment, most apparent when he released his second encyclical last May 2015. According to a report from the United Nations Framework Convention on Climate Change, "Laudato Si" discussed climate change and how it's a moral issue that's part of the Church's responsibility to protect the world and its citizens.

"Our relationship with the environment can never be isolated from our relationship with others and with God," Pope Francis explained in "Laudato Si", according to Catholic Relief Services.

His words -- and the consequent environmental movement it inspired among the faithful -- have placed him on the same side on the battle against climate change as DiCaprio.

The Academy Award-nominated actor has been a long-time environmental advocate, even opening the Leonardo DiCaprio Foundation in 1998 for sustainability initiatives, according to the report from Fox News Latino.

Recently, he took to the stage at the World Economic Forum in Switzerland, where he announced the foundation's donation of $15 million for environmental projects. A report from National Post revealed that he also appealed to the business-centric audience, telling them to help fight against global warming and not "allow the corporate greed of the coal, oil and gas industries to determine the future of humanity."