Al Gore said on Thursday that Americans must abandon electricity generated by fossil fuels within a decade and rely on the sun, the winds and other environmentally friendly sources of power, or risk losing their national security as well as their creature comforts.

He cited military-intelligence studies warning of “dangerous national security implications” tied to climate change, including the possibility of “hundreds of millions of climate refugees” causing instability around the world, and said the United States is dangerously vulnerable because of its reliance on foreign oil.