We always see the moon, of course. The closest planets too, Mars and Venus. And then some other celestial bodies, the most luminous. But that’s about all there is to see in our urban and suburban landscapes at night. The rest – the luminous ribbon of the Milky Way as well as the 6,000 stars and other celestial objects that should be seen the blind eye in the best night skies– was absorbed by artificial light. “The stars are still there, but no longer for us”, says nicely Johan Eklöf.
Finding this spectacle is one of the reasons why the Swedish zoologist, a great specialist in bats, has just published his appeal Let’s dare the night (Tana Editions), a manifesto against light pollution. A second reason is the quest for sobriety when lighting represents a tenth of all our energy consumption and only a fraction is really useful to us.
Again Johan Eklöf mentions it in his book. But the researcher above all deciphers the harmful impact of this light pollution on living things, to the point of hastening the disappearance of certain species a little more. While the fourteenth edition is being held this Saturday from day to nighta major event to raise awareness of light pollution, Johan Eklöf responds to 20 minutes.
What fraction of the globe still escapes light pollution?
There are no exact statistics. Of course, there are still preserved spots. In the open sea, in high mountains, in the middle of deserts, in certain nature reserves. The International Sky Association (IDA) lists several of these places, with its International Dark Sky Reserves (Rice) which must meet the criterion of being relatively accessible. There are about forty in the world, including four in France. In other words, little. It is not a surprise. Images of the Earth, taken from space, allow us to see the expansion of the urbanized world and the resulting artificial light. This is one of the most powerful symbols of the Anthropocene. It is now estimated that 99% of people in Europe and North America now live under influenced skies. Certainly to varying degrees. We are less exposed to this pollution when we live in a small village or in a remote place than in town.
When did light pollution start to become a real environmental problem?
We can go up to Thomas Edison. By patenting a bulb for commercial use in 1879, he ushered us into a new era. There are many good things to say about technical progress, the benefits of modernity and its enlightenment. But there are also counterparts, including light pollution, which was for a long time an underestimated example. This light pollution became a major problem from the moment we began to use massively light-emitting diodes (LEDs) in the second half of the twentieth century, with a strong acceleration from the 1990s. It was these LEDs, cheaper and less energy-consuming, which made possible the explosion of light that we see today in the gardens of villas, car parks, industrial zones, deserted offices… This eagerness to light up everything no longer only responds to our fear of the dark, this terror inscribed in our genetic and cultural heritage. It has become a way of exposing his wealth, his power. the Luxor Sky Beamthis luminous object which tops the Luxor hotel-casino in Las-Vegas, and which projects a ray of light straight towards the cosmos and visible at a distance of 70 km, is an illustration of this.
The fight against light pollution is often approached from the angle of energy sobriety, at least in France. Why is fighting against it also an issue to better preserve the living?
No less than a third of all vertebrates and almost two thirds of all invertebrates are nocturnal animals. We forget it, but it is therefore after we fall asleep, in the evening, that most of nature’s activity takes place. From hunting to mating, to pollination. By prolonging the day with artificial light, we are disrupting this nightlife in so many ways that we are only just beginning to grasp. It’s not just about animals no longer finding that protective darkness that shields them from their predators. Many also rely on the stars, moon or polarized light for orientation at night. Insects, migratory birds, marine animals…. Artificial light blurs their bearings, but sometimes it also acts as a decoy. This is the case for baby turtles that hatch on the beach and often head for cities, attracted by their lights, instead of the ocean. We have all also seen insects as if hypnotized by a beam of light. They circle around all night, unable to escape, becoming easy prey, dying of exhaustion or finding themselves in the early morning, without having achieved the objectives of the night: eat, transport pollen, lay their eggs… C This is another impact of light pollution: it sometimes even affects the ability of certain animals to reproduce.
All living beings, in the end, are affected in one way or another by light pollution?
Since the birth of the Earth, night has succeeded day. Every cell in every living organism is programmed to function in harmony with this rhythm. Light calibrates our internal clock, it controls hormones and other biological processes. We are a good example. Between sunset and midnight there is a steady increase in the rate of melatonin [une molécule souvent dénommée hormone du sommeil] which in turn triggers a large number of reactions in the body. We are tired, our body temperature drops, as well as our metabolism or our appetite. This is because melatonin activates a another hormone, leptin, which tells us the state of our energy reserves and the best way to manage it. Here again, light pollution contributes to disrupting the melatonin cycle with the consequence of maintaining a constant low level of leptin in our body, which also contributes to the current increase in obesity.
Is light pollution the easiest environmental problem to solve?
Technically yes, at least compared to global warming, plastic pollution, the scourge of invasive species… In a way, it is enough to turn off superfluous light, equip the lamps with lampshades, adopt low light sources and oriented downwards… And then the LEDs, which have so far contributed to gleaning a little more at night, can have the exact opposite effect. The light palette of the LED bulb is more extensive than in the past, you can vary the intensity as you want. It is also possible to control the duration of the lighting, to program it, to imitate the natural variations… It is time to use this technical palette. Unfortunately, light pollution continues to increase. I note all the same that this is a booming field of research and that initiatives to reduce this pollution are multiplying around the world. From the neighborhood of Roppongi Hillsin Tokyo at the island of Mon in Denmark [où la partie Est a été transformée en réserve naturelle consacrée à la nuit en 2017]passing by France which, even if the decrees are not always well applied, remains one of the rare countries to have legislated on light pollution.
You begin your manifesto with a call to become aware of darkness… What do you mean by that?
That we must question our need for darkness as much as our need for light. Both are vital for much of life, including us. We cannot always combine these two needs. It will sometimes be necessary to make choices, leaving places under the light and others in the dark. This can be done even on a city scale, leaving parks in darkness with corridors connecting them. It is certain, in any case: it is necessary to protect the darkness, to (re) discover it. Only then will we become aware of the real threat posed by light pollution.