The stars are co-founders of the 100% movement and they launched their new project in New York City on Thursday night (18Jun15), urging fellow eco-warriors to support their cause by putting pressure on lawmakers to do more to save the planet and boost the economy at the same time.

Speaking at the event, which was held at a community garden, DiCaprio said, "This is a grassroots people's movement but the ambition of this movement is absolutely revolutionary. Clean energy grows local economies."

Ruffalo added, "This is really mankind's greatest threat, and it should take some serious problem-solving on all of our parts. And we don't really have to give up anything to do it..."

Touting clean energy sources like solar and wind power, he continued, "We will be collecting the sun and the wind that falls (sic) on us every single day."

The 100% launch took place hours after Pope Francis made his own plea to global citizens, calling for swift action to combat climate change.

The actors previously joined forces last year (14) to take part in the Big Apple's People's Climate Change march ahead of the United Nation's environment summit, where DiCaprio, the new U.N. Messenger of Peace on Climate Change, addressed attendees and hammered home his message for urgent action.