In a recent TED Talk (video below), climate warrior and former Vice President Al Gore spoke about the destruction climate change has caused in recent years, from typhoons in the Philippines to historic downpours in Houston to floods in Spain to unprecedented wildfires in North America. “Every night on the TV news now is like a nature hike through the Book of Revelations,” Gore says.

And yet, despite all of this, Gore is optimistic. And the main source of his optimism is renewable energy. The cost of renewable energy is dropping, Gore points out, while availability is increasing exponentially and far more rapidly than projected.

Take Germany, which has greatly increased its use of solar and wind power in the past several years. On Dec. 26, 2015, over 80 percent of all power generated in that country came from renewables, according to Gore. That’s a huge accomplishment, and one Gore sees continuing. And it’s not just the industrialized world: Parts of the planet that until now have never been electrified are seeing successful pay-as-you-go solar systems in places like Bangladesh and South Sudan.

These developments show that we can change, Gore says. From China’s cap-and-trade system to coal plants going offline in the U.S. to climate marches around the world to the Paris climate talks last December, we are solving this crisis, according to Gore. And the only question, he says, is how long will it take?