In 2003, someone leaked a “secret” Pentagon report warning of the dire consequences of climate change.

“Disruption and conflict will be endemic features of life,” it reads. “Once again, warfare would define human life.”

The report’s authors offer dramatic examples, including the claim that “catastrophic” shortages of potable water and energy would lead to widespread war by 2020. Britain would have winters similar to those in Siberia as European temperatures drop off radically by 2020.