Former Vice President Al Gore, a climate change activist, made claims on Monday that global warming will result in the "potential for tens of millions of refugees" entering the United States.

Speaking with ThinkProgress, Gore claimed that the number — should climate change play out the way he thinks it will — could be even higher.

Gore said:

"The Max Planck Institute and others are now saying that some significant regions of the Middle East and North Africa may become uninhabitable because of the rise in both the temperature and humidity. And that will increase the flows of refugees. Africa by mid-century will have more people than either China or India, and by the end of the century more people than India and China combined."

He said that as a result of climate change, "20 million people" are on the "verge of famine."

About climate change impacting refugees, Gore said, "This is a major, major challenge. Just as the next six or eight months are going to be particularly challenging for American democracy, the next several decades are going to be a test of the character and courage for humanity."

Gore is currently on tour to promote his latest film, "An Inconvenient Sequel," which is a follow-up to his 2006 film, "An Inconvenient Truth," based on his book from the same year.

In June, Gore compared the importance of combating climate change to championing human rights.

During a speech at the EcoCity World Summit in Melbourne, Australia, Gore said, "The climate movement is right now in the tradition of all the great moral causes that have improved the circumstances of humanity throughout our history. The abolition of slavery. Women’s suffrage and women’s rights."

He added, "All of these movements have one thing in common: they all have met with ferocious resistance and have generated occasional feelings of despair from those who knew the right direction and wondered whether we could ever get there.”