Darkened Cities

"A hundred times I have thought New York is a catastrophe...it is a beautiful catastrophe." Le Corbusier, quoted in the New York Herald Tribune, 6 August 1961

"The City is of Night; perchance of Death, but certainly of Night." The City of Dreadful Night, Poem by James Thompson, 1874

You might be forgiven for thinking that – of all things – the stars were equal above us. Too far, too big, too old, to be affected by anything that puny man could do. The stars look down upon us with benevolence or with despite, according to the mood of the poet, and our language is rich in reminders of how mankind has thought its destiny written in the stars. Star-crossed lovers look for lode-stars, and it sometimes seems that every writer stuck for a word has merely to look up to find his all-purpose answer in the stars. Shakespeare once called them the bad revolting stars. Traditionally, the stars affect us and we can do nothing in return. Yet now it seems that mankind's infinite capacity for messing things up has reached even to the stars.

In Thierry Cohen's series, Darkened Cities, we think we see bright night skies over cities. Very traditional, very poetical. Actually, what we're seeing is the opposite. These skies are an indictment and a lament. These are the skies that we don't see. They are also extremely clever photography, in which highly skilled execution provides rich layers of meaning.

The principal operation that has to take place before these pictures can exist is that the sky from one place has to be superimposed upon cityscape from another. The reason is simplicity itself. As every amateur astronomer knows, it is impossible to see this detail in the night sky above a city. Modern lighting provides a level of light pollution so high that looking into the urban sky is like looking past bright headlights while driving. Add to that the atmospheric pollution above any city, and you have a screen only barely penetrable by light. Stand in New York or Rio and look up, even on the most cloudless night, and you won't see Cohen's explosions of light. Yet it is there, blotted out only by man's interference.

The first photographer to split his photographs horizontally in two, specifically to even out the luminous balance, was the nineteenth century French master Gustave Le Gray. Le Gray, a fine technician at the very point of technology, found that the emulsions available in his day could not record equally well the bright sky and the twinkling water in the great series of poetic seascapes that he made in the 1850s, so he made them from separate negatives for sea and sky. The convenient straight line of the horizon helped him both to join them and to conceal the join from his viewers.

Cohen is also a fine technician, who has practised digital photography for longer than almost anyone else. But he is not practising for virtuosity alone. Cohen does not merely replace one sky with another for convenient photographic legibility. By travelling to places free from light pollution but situated on precisely the same latitude as his cities (and by pointing his camera at the same angle in each case), he obtains skies which, as the world rotates about its axis, are the very ones visible above the cities a few hours earlier or later. He shows, in other words, not a fantasy sky as it might be dreamt, but a real one as it should be seen.

This is a very powerful treatment. It is laborious in the extreme. To find places with the right degree of atmospheric clarity, Cohen has to go – always on the latitudes of our cities – into the wild places of the earth, the Atacama, the Mojave, the northern wastes of Mongolia. Who among us beyond a handful of professional astronomers would know if Cohen cut the odd corner by finding a good sky not quite so remote? But photography has always had a very tight relationship to reality. A good sky is not the right sky. And the right sky in each case has a huge emotional effect.

As more and more of the world's population becomes urban, and as we lose our connection with the natural world, so it becomes plain what damage is caused. Are there injurious effects of light pollution? Quite possibly. To people there may be physical connections to certain cancers, and there are surely psychological burdens of permanent day. To other natural life, flora and fauna, the damages are wide-reaching. The 'city that never sleeps' is made up of millions of individuals breaking natural cycles of work and repose. Lose sight of the sky, and you become a rat in a lab. We're all heading that way. It may come to it that we can never properly see the sky again. Already there are produced maps of the intensity of pollution by light which are so bright they're scary. There are still gaps where you might see the sky, but they're not where we all live.

Cohen hasn't simply shown us the skies that we're missing, by the way. His process is many degrees more complex than that. Notice how dead his cities look, under the fireworks display above? No lights in the windows, no tracers of traffic? Barely even reflections of the blazing starry glory above. That's because they are in fact photographed in the daylight hours, when lights are switched off or shine out less brightly. How clever this is, each photographic obstacle to Cohen's expression isolated, and solved to perfection.

There is an urban mythology which is already old, in which the city teems with energy and illumines everything around it. All roads lead to Rome, we were told. Cohen is telling us the opposite. It is impossible not to read these pictures the way the artist wants them read: cold, cold cities below, cut off from the seemingly infinite energies above. It's a powerful reversal, and one very much in tune with a wave of environmental thinking of the moment. Look at the work of Sebastiao Salgado, for example, who used to show specific areas of distress (geographical or social) until his subjects grew bigger until now (in the series entitled Genesis) he is working to tell us about the health of the planet itself. Thierry Cohen didn't merely find pictures that pointed so sharply to the blight that our mega cities have become, he couldn't. He made them instead, with patience and skill and the driving desire to be understood.

Night time is as attractive to photographers as it is to poets. One thinks in a moment of the terrestrial nights of such artists as Brassaï, for whom the night was a stage of its own. René Burri, the great Swiss photographer, rushed out into the New York blackout of 5th November, 1965 with only 8 rolls of film and made 40 of the greatest pictures of a city at night that you will ever see. Weegee loved the night, of course, and Nan Goldin, and Bill Brandt and dozens of other photographers of the city. It's particularly a city thing, you see. In the country, when it gets dark, you go to bed. It's in the cities that we go mad a little at night. Cohen's fine series shows that he understands this. Zoom in on one any of these pictures, I feel, and you'll find oily dark scenes from Weegee in every window.

Francis Hodgson, London 2011