The effects of ‘weird weather’ were already being felt in the 1960s, but scientists linking fossil fuels with climate change were dismissed as prophets of doom

In August 1974, the CIA produced a study on “climatological research as it pertains to intelligence problems”. The diagnosis was dramatic. It warned of the emergence of a new era of weird weather, leading to political unrest and mass migration (which, in turn, would cause more unrest). The new era the agency imagined wasn’t necessarily one of hotter temperatures; the CIA had heard from scientists warning of global cooling as well as warming. But the direction in which the thermometer was travelling wasn’t their immediate concern; it was the political impact. They knew that the so-called “little ice age”, a series of cold snaps between, roughly, 1350 and 1850, had brought not only drought and famine, but also war – and so could these new climatic changes.

“The climate change began in 1960,” the report’s first page informs us, “but no one, including the climatologists, recognised it.” Crop failures in the Soviet Union and India in the early 1960s had been attributed to standard unlucky weather. The US shipped grain to India and the Soviets killed off livestock to eat, “and premier Nikita Khrushchev was quietly deposed”.