The seas of southern Europe are a mass grave. This is no secret, nor is it the first time these ebullient waters have harboured the dead en masse. From ancient Persian warships to hulking WWII destroyers, the Mediterranean and Aegean are littered with the carcasses of millennia of military conflict.

The difference is, of course, that today’s victims wear puffer jackets and denim jeans and are running low on phone battery. They are not just men, but women and children of all ages. And almost all are fleeing conflict, not feeding it.

When in September 2015 the body of three-year-old Alan Kurdi washed up on the very Turkish beach his family had paid almost $6000 to escape hours earlier, the western world fell into a collective spasm of sympathy. Reams of written accounts and hours of footage recorded the fraught landings of dinghies filled twice to capacity at Lesbos and Malta, Sicily and any other ounce of European frontier they could reach. The UN estimated that, of the million who sought to enter Europe that year by sea, almost four thousand drowned instead. Tears were shed and bold promises made, but that was 2015 and they have  since been obscured by turbulent Brexit negotiations and a President who orders Diet Coke to his desk via a special button. The refugee crisis has been reduced to a simmering backlog of perfunctory, muted outrage.

So it is with admirable and perhaps accidental precision that world renowned Chinese artist and activist Ai Weiwei premiered his feature-length documentary, ‘Human Flow’, at the Barbican last week – an attempt to chronicle the global refugee crisis on an unprecedented scale. Weiwei is no stranger to displacement himself; formerly detained by the Chinese authorities and subjected to psychological torture, he was subsequently  released and set up residence thousands of miles away in Berlin.

65 million people have, as of 2015, been displaced by conflict or persecution – a population greater than that of the United Kingdom and equivalent to one in every 113 people on earth.  Weiwei is far from the first to capture this humanitarian tragedy, but he is the first to do justice to its scale. Filmed across 23 countries, Weiwei cartographically fires us across a staggering canvas of marginalisation, from Greece to Kenya, Lebanon to Myanmar.

His lens naturally lingers on Europe, and what a sight it is. Like the perverted inversion of a Bond film, each nation is grandly introduced via place-cards (NORTHERN GREECE, ITALY) but darkly subverts expectations.  Northern Greece hangs heavy with smudged skies and curtains of rain as a column of colourful rucksacks and waterproofs trudges towards Montenegro. Italy is a dark, windswept landing site full of barking officials and belching buses. There are no Louvres or Duomos here, only flapping tents in oily railyards and endless stretches of impenetrable border fence. Familiar place names but not familiar places. It struck me as eerily similar to director Alfonso Cuaron’s depiction of a dystopian Britain in Children of Men, a place where migrants are treated like cattle in divided pens. As if to illustrate this, Weiwei highlights that in 1989, after the fall of the Berlin Wall, there were only 15 border walls around the world. Now there are 70.

Yet on the whole, Weiwei is not telling us anything particularly new. That is not the point. What he does is use staggering cinematography to capture the scale of the crisis in a way that  statistics cannot. To do this, he appears to have amassed a small army of drones that glide silently across Jordanian camps and hover trepidatiously in the bombed-out living rooms of Kurdistan. It is undeniably stunning. One notable shot draws silently away from a fluorescent mountain of discarded life jackets. The detritus of desperation is laid bare. Another sits atop a captive tiger’s pit in Gaza – his dusty incarceration mimics that of the two million Palestinians imprisoned around him.

But arguably this moribund splendour is at its most potent near the end of the film, when Weiwei takes us to one of the many starting points of people’s journeys, and we see what they are running from. Mosul is shown here unlike I have ever seen it – a vast concrete graveyard, the iconography of urban life shattered and dropped into darkness by plumes of thundering black smoke, behind which a stifled sun drips a blood-orange hue into the gloom. Cows flee and a dead child lies with his stomach blown out as oil fields burn apocalyptically on the horizon – the last great shadow cast by Islamic State’s retreating black flag. It is surreal and horrific. It is immensely powerful. And it throws 2016’s embarrassing EU-Turkey deal (in which irregular arrivals in Greece would be returned to Turkey in exchange for €6 billion and Visa-free travel to Europe) into sharp relief.

But herein lies the problem. ‘Human Flow’ is too beautiful. Weiwei, ever the artist, has infused a sense of poised elegance and cinematic sheen into what is, in reality, a maelstrom of human suffering.  This weaves an eerie, manicured order into events that are, by definition, amorphous and utterly chaotic.  It is an impossible compromise between artist and subject when the two, in this case, are almost necessarily antithetical to one another. The burning of the Calais ‘Jungle’ becomes a spectacle as much as a travesty. And even the title, ‘Human Flow’, imbues the process with a naturalistic rhythm and order that is heretical to the very essence of forced migration.

But this is a small price to pay for the world Weiwei reveals to us; one he can scarcely interrogate but can at least witness, impotently as we all do but with an eye wider than most, until the clamour of human suffering becomes too great to bear and there is nothing left to say, except to remain absolute, as Weiwei does, that this is not simply ‘a refugee crisis’ but a ‘human crisis’.

‘Human Flow’ is directed by Ai Weiwei