Arnold Schwarzenegger is urging world leaders to join hands to save the planet from the devastating effects of climate change. The former California governor says climate change is not science fiction and must be dealt seriously.

The 67-year-old actor and politician made his speech at the first “summit of conscience for the climate,” held in Paris on Tuesday. Schwarzenegger has been selected by French President Francois Hollande as an advocate for environment, ahead of the United Nations summit on climate change in December. Schwarzenegger will join Pope Francis, U.N. Secretary-General Ban Ki-moon and several Nobel Peace Prize winners in the summit.

“I’ve starred in a lot of science fiction movies and, let me tell you something, climate change is not science fiction. This is a battle in the real world; it is impacting us right now,” said Schwarzenegger.

Schwarzenegger further said that to tackle the problem of climate change is the “challenge of our time” and it is our responsibility to leave this planet better than we received it. People are failing future generations, he said.

Kofi Annan, the former U.N. secretary-general, warned: “If action is not taken immediately, my grandson will live in a world suffering heat waves, severe droughts and floods. Cities like New York and Venice will drown,” he said. “We are on the brink of catastrophe, but the solution to the climate crisis cannot be left to governments alone. People are taking the lead and demanding change. We must not fail them.”