Police cars can’t fly, artificial snakes are not commercially available, and the exodus to off-world colonies has not yet begun, but we’re already living in the world of Blade Runner – chronologically, at least. The original movie is set in 2019. Rutger Hauer’s replicant-in-chief has been activated since January 2016. He might be watching attack ships off the shoulder of Orion as we speak.

Looking ahead, we’re entering the uncomfortable era when many “futuristic” movies are set – usually of the dystopian, apocalyptic, “you really don’t want it to turn out like this” variety. If they’re anything to go by, we’ll be lucky if we make it to 2049, when the forthcoming Blade Runner sequel is set.

According to The Running Man, for example, the economy collapses this year. Art and communications are outlawed, and the United States is a repressive police state in thrall to sadistic reality TV – pure fantasy of course. Rollerball, set in 2018, predicts a similarly grim outcome. Meanwhile, horror series The Purge also begins this year: a night of violence and anarchy sanctioned by a totalitarian, civil rights-quashing US government – a climate eerily reminiscent of the Charlottesville protests.

Back to the future again ... watch the trailer for Blade Runner 2049.

More remote, but equally worrying, is anime par excellence Akira, set in 2019, when Tokyo has been destroyed. By ominous coincidence, its replacement, Neo-Tokyo, is due to host the 2020 Olympics – just like the real city will, assuming it’s still there.

But don’t worry: according to the sci-fi calendar, we’ve only got five years until global warming and overpopulation have us all eating Soylent Green anyway. And if we stick that out, we might get to 2026, the age of Metropolis. Even in the 1920s, the proto-sci-fi epic was laying out a pretty similar dystopia to that of Blade Runner, though its happy ending would be more heartening if we weren’t straight into Children of Men in 2027, by which time humanity is infertile and Britain is rounding up refugees in camps. It’s almost as if they foresaw Brexit.

Are the dates arbitrary? Fritz Lang merely set Metropolis 100 years on. Philip K Dick’s source novel for Blade Runner, written in 1968, was originally set in 1992. Or could it be that these sci-fi visionaries subconsciously intuited that this was about as long as modern society had? The way-off future is often brighter (Star Trek is in the 23rd century), but the most effective dystopias are ones we can imagine living long enough to experience, and therefore do something to avoid.

Blade Runner 2049 is in cinemas on 6 October