Former Vice President Al Gore appeared on The Circus Sunday night and reiterated his belief that climate change is responsible for the migrant caravans from Central America heading to the U.S. To prove his point Gore showed an area, spanning several countries, that is known as the Dry Corridor, part of which is so dry it’s gone an entire year without a harvest. This, according to Gore, is where the journey begins for many migrants.

“The drought becomes unbearable, so they pick up stakes and they say, ‘We can’t live here,’” Gore said. “First of all, they leave their farms and go to these cities, and they run into these criminal gangs, and they say, ‘We can’t handle this.’ And they head on north.”

If what Gore says is true, the caravans won’t be stopping anytime soon — not just from Central America to the U.S., but all over the world.

“The estimates are that in this century there could be as many as 1 billion climate refugees migrating across borders to other countries,” Gore said. “That’s a threat to political stability and peace.”

Donald Trump, and many other Republicans, deny that climate change is real, or at the very least deny that humans are responsible for the speed at which it’s happening. But according to Gore, there are those who say one thing in public and something entirely different in private.

“There are a lot of Republicans who I know who understand the climate crisis,” he said. “But if they say they’re on my side of this, then they get a primary opponent, and so they keep quiet about it.”

The Circus airs Sundays at 8 p.m. on Showtime.

Check out what Alexandria Ocasio-Cortez said is the silver lining of Trump’s presidency:

Read more from Yahoo Entertainment:

Tell us what you think! Hit us up on Twitter, Facebook or Instagram, or leave your comments below. And check out our host, Kylie Mar, on Twitter, Facebook or Instagram.