Although many may know Nikolaj Coster-Waldau as the cunning, king-slayer Jaime Lannister on “Game of Thrones,” in real life, the actor is gaining attention for fighting a different kind of battle: global climate change. In this op-ed for CNN, Nikolaj shares why he personally believes the world must take immediate climate action.

As someone who has spent considerable time in Greenland, he has seen the alarming effects of rising temperatures on delicate ecosystems firsthand. Nikolaj warns that what is happening on the ice-covered island has global ramifications. If the Greenland ice sheet melts, scientists predict that sea levels would rise 20 feet, affecting vulnerable coastal cities around the world. To galvanize climate action, Nikolaj acts as a goodwill ambassador for the UNDP and an executive partner of the UNLEASH lab, which aims to elevate youth engagement with innovative solutions for the Sustainable Development Goals.