Our ruling: Sanders said, "Climate change is directly related to the growth of terrorism." - We couldn’t find any evidence of a "direct" relationship between climate change and terrorism, though many reports have noted an indirect link. There are, of course, many other factors that contribute to terrorism, including religious and ethnic tensions and political repression. We rate Sanders' claim Mostly False.
A Central Intelligence Agency report from 1974 warned Earth’s “climate is returning to that of the neo-boreal era… an era of drought, famine, and political unrest in the western world.” The report cited famines in the Soviet Union, drought in Latin America and flooding in the U.S. as examples of how global cooling was wreaking havoc on countries.
This sounds eerily similar to arguments Sanders made during the Democratic presidential debate.
Interestingly enough, the Pentagon has the same concerns about global warming as the C.I.A. did about global cooling in the 1970s. “The impacts of climate change may cause instability in other countries by impairing access to food and water, damaging infrastructure, spreading disease, uprooting and displacing large numbers of people, compelling mass migration, interrupting commercial activity, or restricting electricity availability,” the Pentagon reported in 2014.
WWF International: "Transformative change is urgently needed in our productive sectors, including our food systems, forestry, fisheries, infrastructure and extractives, and in the finance sector. These transformations need to happen fast if we are to limit risks of higher restoration costs and irreversible damage, including new pandemics and species extinction. We must transform our food systems so that enough healthy and nutritious food is produced for all, within planetary boundaries."