Leonardo DiCaprio and Secretary of State John Kerry spent time together discussing solutions for global warming at a climate summit in Paris.

DiCaprio, who has been appointed U.N. Messenger of Peace for the Climate, and Kerry, who fought for environmental reform during his time in the Senate, joined hundreds of world leaders in the public and private sector gathered for the the Paris Climate Conference, or COP21 (Conference of Parties), held from Nov. 30 to Dec. 11.

Get push notifications with news, features and more.

The Revenant star plans to hold private meetings with top climate change officials throughout the conference, and was photographed having a sitdown with Kerry on Monday.

The Secretary of State tweeted a picture of the meeting, captioning, “Great to see my friend @LeoDiCaprio at #COP21 — one of the most committed advocates for our ocean and our planet.” Dicaprio wrote back Tuesday morning, saying, “Great seeing you, too. Thank you @JohnKerry for all you’re doing at #COP21.”

The actor and activist sits on the boards of the World Wildlife Fund and the Natural Resources Defense Council, two groups expected to have strong influences on the talks. In addition, his foundation recently granted $15 million to global conservation efforts.

DiCaprio spoke in front of mayors from major cities around the world on Friday at City Hall in Paris to discuss how they can help avert environmental disaster. “Climate change is the most fundamental and existential threat to our species. The consequences are unthinkable and worse, it has the potential to make our planet unlivable,” he said, according to The New York Times.