All the Dark We Cannot See
Illustration by Kazimierz Wiśniak

All the Dark We Cannot See

The Disruptive Effects of Light Pollution
Agnieszka Fiedorowicz
time 15 minutes

“The night sky is the heritage of all humanity, which should therefore be preserved and untouched,” proclaims the resolution of the International Astronomical Union. Excess light affects not only the lives of humans, but also interferes with the functioning of animals and plants. We need darkness to survive, just as we need light.

“When I think of dark nights, I think of this lake in northern Minnesota. On the longest day of the year, my father and I watch as the sun sets across the water and night begins filling a clear sky. Soon the Summer Triangle stands directly over us, Scorpio rises from the bay to the left. […] As a child I was afraid of night at the lake because the dark was so thick it seemed tangible […] like drapery. And the woods are still that way, but the sky is beginning to wear at the edges where gas stations hope to attract customers by immolating themselves in white light, and roadside restaurants blow their electricity bills straight into the sky. Each summer when I return to the lake I am no longer so much afraid of the dark as I am afraid for the dark,” wrote Paul Bogard in his essay published in the collection Let There Be Night: Testimony on Behalf of the Dark. Bogard, who is a professor of creative writing at James Madison University in Harrisonburg, was one of 28 authors explaining how important darkness is for humans. This isn’t Bogard’s first book on the topic. Five years ago, he wrote The End of Night: Searching for Natural Darkness in an Age of Artificial Light, where he explained how an excess of light can affect and disrupt the functioning of humans, animals and plants. “Just as we need light, we also need darkness to live,” he argues.

Shedding light

To, as it were, shed some light on the problem, let’s take a look at satellite photos of the Earth. A mere glimpse is enough to realize the scope of light pollution – that is, the presence of light at wrong times or in larger quantities than what the organisms inhabiting our planet are used to. Yes, it does look lovely. Trillions of light clusters illuminating human settlements weave intricate webs and geometric patterns. Dark spots are much harder to come across.

“The Earth’s night is getting brighter. I actually didn’t expect it to be so uniformly true that so many countries would be getting brighter,” says physician Christopher Kyba from the GFZ German Research Centre for Geosciences, who led research published in the journal Science Advances in 2017. His analysis of data collected by NASA satellites between the years 2012 and 2016 suggested that the scope of artificial night-time light on Earth grows by 2% per year. This problem is no longer an issue only for the densely-populated United States of Europe, but also South America, Africa and Asia (the only areas where this percentage dropped instead of growing were the war zones of Syria and Yemen). The scale of the Earth’s level of light pollution is just a rough estimate – weather satellites are unable to detect some light produced by LED lamps, which are becoming increasingly popular. Scientists estimate that a staggering two-thirds of the human population live in light-polluted areas. In the US and Europe, this problem affects 96% of all people. The areas of the most light-polluted cities in the world, such as Hong Kong, Las Vegas or Tokyo, are up to a thousand times brighter than they would be without artificial illumination.


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“It is hard to accept that artificial light, such an important human invention, could be harmful to us,” says Magdalena Markowska, a physiologist in the Department of Animal Physiology at the Faculty of Biology of the University of Warsaw. As Markowska notes, the problem has been growing ever since we began using fire as an additional source of light in caves and other dark areas, but the real shift happened after mass electrification in the 20th century. The universal availability of light today makes us use it more and more. We cannot imagine our cities, highways and petrol stations unlit at night. Unfortunately, a large part of this light goes straight up into the sky. Spherical street lamps send only 40% of light towards the ground, and arc lamps send just 50%. When the lamp is dirty, energy loss can amount to a staggering 80%. Estimates made by the International Dark-Sky Association (IDA) conclude that one-third of all light in the US is wasted this way. In Europe, almost €2 million are being beamed straight into the sky by street lights every year. Experts had hoped for the more effective LED lights to be a game-changer. Kyba admits that some energy savings were noted locally after replacing sodium street lamps with LEDs, but further analysis proved that these profits go to waste, because more spots are illuminated with thicker and brighter networks of light sources.

The first to take note of this problem were astronomers – excess light in the atmosphere causes the skyglow effect, making it impossible to observe astronomical objects, such as galaxies or nebulas. Already in 1947, an increase in light pollution was the reason behind moving the famous Royal Greenwich Observatory to Herstmonceux Castle, 70 kilometres south-east of London. Today, astronomical observatories are located far away from cities. They are built instead in deserts or on mountains.

Days getting longer

“Do we need darkness?” I ask Markowska. “Absolutely,” she says. “Our biological clocks are synchronized with times of the day, and once this rhythm is thrown off its axis, problems begin. Overexposure to light stops the release of melatonin. This hormone, produced in the pineal gland, regulates our circadian rhythm, telling our cells it’s time to rest,” explains Markowska. Melatonin deficiency leads to many health issues, the most common being insomnia and the other sleep problems that plague most of our society. Data collected by the National Sleep Foundation in America show that over the course of the past century, our sleep time has decreased by an average of three hours – from nine or ten hours to less than seven. In Poland alone, 25-40% of the population experience sleep disorders.

A lack of sleep affects our ability to concentrate and memorize information, and it increases the risk of diabetes and obesity. “Artificial light prolongs our perceived daytime, which makes us work and eat late into the night, which can result in weight gain,” Markowska says. A survey conducted among over 100,000 British women showed that overexposure to artificial light in the bedroom was linked to higher BMI rates. “This deregulation makes us live in constant micro jet lag, often paired with so-called social jet lag for those who work late or at night. Those people, wanting to adjust to their families and friends, often give up on sleep to function during the day,” continues Markowska. “Melatonin is also responsible for regulating our immune system and cleansing our bodies from free radicals. That is why insufficient levels of melatonin are connected to cancer.”

The first study confirming this hypothesis was carried out on nurses who worked night shifts. Richard Stevens, an epidemiologist from the University of Connecticut, proved that night-shift-working nurses were twice as likely to experience breast cancer than those working during the day.

The worst damage to our bodies is done by blue LED light, attacking us from our now-omnipresent smartphone and tablet screens, which we often take to bed with us. “Melanopsin is a photopigment found in retina cells. It regulates our circadian rhythm and is most sensitive to blue light,” Markowska tells me. A 2016 American Medical Association report warned that 24-hour lights can lead to an intensification of many health issues, including diabetes, depression and fertility disorders. The organization calls for limiting exposure to damaging LED lights, especially street lights.

Don’t follow the light, turtle!

In 2010, when the Tribute in Light was first illuminated – two columns of light commemorating the victims of 9/11 – those watching noticed a mass of moving sparks around the lights. It was migrating birds that had lost their orientation. Two years earlier, ecologists had already introduced a project intended to protect these birds from harmful light effects. Whenever the lights attracted too many birds, the monument was to be switched off for a while. Despite these measures, researchers discovered that over the course of eight years, Tribute in Light attracted and disoriented over a million birds.

Almost 200 years prior, the Swedish-American ornithologist Ludwig Kumlien had already noticed that an illuminated observation tower in Milwaukee was attracting birds that often hit it and crashed. During the night, birds use the Moon and stars for navigation. Artificial light disorients and confuses them. They hit brightly-illuminated chimneys, lighthouses and oil rigs, or they start circling around these objects until they drop from exhaustion. Sometimes, entire flocks fall victim to the treacherous lights. In 1981, over 10,000 birds crashed into the brightly-lit chimney stacks of the Hydrox Generating Plant near Kingston, Ontario.

An ecologist from the Leibniz Institute in Germany, Franz Hölker, notes that light pollution is especially harmful to vertebrates (30% of which are nocturnal) and invertebrates (60% nocturnal). “Light pollution threatens biodiversity through changing the night habits (such as reproduction and migration) of insects, amphibians, fish, birds, bats, and other animals. It can also disrupt plants by distorting their natural day–night cycle,” explains Hölker.

“Many animals use daytime lengths to follow seasons. Deer mate in the autumn so they can have their young in the spring. Rodents’ reproductive systems shut down in the winter and restart in the spring,” says Markowska. Artificial light can disrupt these cycles and make animals reproduce too soon or too late. Davide Dominoni from the Netherlands Institute of Ecology in Wageningen has researched and described this phenomenon occurring in common blackbirds. As a result of artificial light exposure, blackbirds’ egg-laying time ended up occurring a whole month too late. “The latest publication from December 2018 shows that LED light reaching deep into the water disrupts the breeding cycle of corals,” adds Markowska.

A 2012 study on leatherback sea turtles on Tobago island – a species that has been living on Earth for 150 million years – showed that artificial light poses a threat to the hatching baby turtles. Instead of crawling towards the water, the young go deeper into the land, mistaking hotel lights for the moonlight reflected on the sea surface. As a result, many die from dehydration, are crushed under car wheels, or fall prey to various predators. Night lights can also stop reptiles from their migrations to and from breeding areas. In an experiment by Bryant Buchanan, frogs stopped mating during night-time football matches, when the nearby stadium lights brightened the sky. Scientists have also recorded lowered melatonin levels at night in storks nesting in the Zielona Góra region of Poland. Among storks, the hormone is responsible for navigating to and from their winter locations. When its synthesis is disrupted, the birds can struggle to find their nests.

These phenomena might seem singular, but they end up disrupting the functioning of entire ecosystems. Eva Knop, who is an ecologist at the University of Bern, has researched the nocturnal activity of pollinators. In cabbage thistle cluster areas where scientists installed artificial light sources, the number of pollinators dropped by 62%, which led the plants to produce much less fruit than usual. Further research proved that artificial lighting significantly affects bat foraging – by eating various pests and insects, these mammals contribute significantly to increases in harvest volume.

There are many places where ecologists, along with local governments, are working on solutions that could better protect animals. The Florida Fish and Wildlife Conservation Commission recommends using red LED lights, which do not attract turtles. Similar measures are used in the Netherlands to avoid affecting bats.

Danger in broad street-light

Many cities, from Calgary to Oslo, are modernizing their light systems (for example, by installing lampshades that prevent the light from going into the sky), and equipping roads with street lamps that can change light intensity depending on the weather conditions, traffic intensity, and time of day or night. For the past few years in Paris, the lights in stores, offices and building facades have been switched off between 1am and 7am. Apart from light pollution reduction, these regulations are also expected to limit the emission of greenhouse gasses. Such simple changes are expected to save the French up to €200 million each year.

It’s also worth noting that these new regulations have not caused an increase in crime. “We are taught that darkness is bad and light is good, because light means safety. But does more light really guarantee a safer environment?” asks Paul Bogard in his TEDx talk Why We Need Darkness. Bogard presents two photographs. The first one shows a yard illuminated with a bright reflector. “The light gives us an illusion of safety, and worse, it blinds us with its glare so we cannot see anything at all,” he says. In the second picture, the glare has been covered. Only then can we see a man standing at the gate. He was not visible before, because the light was too blinding. “Crime is not reduced by sending light upward into the sky, or by sending glare into your eyes,” insists Maggie Tracey, an IDA activist in Nevada. There is a lot of research proving that most acts of crime are committed in daylight or inside well-lit buildings. External lights attract attention and even help criminals control their actions, claimed a report published by the US National Institute of Justice, titled Preventing Crime: What Works, What Doesn’t, What’s Promising. This conclusion was confirmed in practice by cities that limit their night-time lights. Over the first months since such a change was introduced in Des Moines in the US, the level of vandalism, theft and break-ins dropped by 3.5%.

Another danger is too many street lights. Drivers react to bright lights by squinting, and often even turn their eyes away instinctively when seeing glaring street lamps or ads. This significantly decreases their chances of noticing any dangers on the road.

Face-to-face with the infinite

Dark skies are becoming a rarity that needs to be protected. In 1988, David Crawford founded the IDA to fight light pollution and protect the so-called ‘dark sky’. IDA sections are now active in several dozen countries all over the world. In 1997, during the 23rd General Meeting of the International Astronomical Union (IAU) in Kyoto, a night sky protection resolution was announced. It claimed that: “[…] the night sky is the heritage of all humanity, which should therefore be preserved and untouched.”

The governments of many countries – including the Czech Republic, Spain and Italy in Europe – are starting to introduce regulations to better protect the night sky from light pollution. There is even a special IDA certificate, awarded to those places in the world where the sky is still genuinely dark. Some of the dark sky preserves include Canyonlands National Park in Utah, and Death Valley National Park in California.

I live in a village almost 40 kilometres outside Warsaw, but in searching for a truly dark sky I go elsewhere, far away to the Bieszczady Mountains in south-east Poland. Six years ago, Bieszczady Starry Sky Park was established (one of two such parks in Poland). “It’s our treasure that others can envy,” says Robert Bury, an astrotourism projects specialist from the Lutowiska municipality. “The first to create a dark sky park were the Slovakians, who inspired us to follow in their footsteps. The Ukrainians were next. These three parks make for a unique dark-sky area, the largest in Europe. Each year, over a million tourists visit the Bieszczady Mountains. There are a lot of people to whom we can show our sky and stars.” More and more of those visitors are astrotourists, coming here to watch nebulas or galaxies that cannot be seen from cities – not even through a telescope. Paweł Duris, an amateur astronomer, has been organizing special night shows for tourists in Przełęcz Wyżna and in Dwernik village. He also provides telescopes to astrotourist companies and guest houses.

After the night sky presentation, I go to a terrace of Pałac Biesa in Olszanica, where I’m staying, and gaze at the Milky Way. I know my children have never seen this many stars. I have to bring them here and show them the stars, because it’s possible that soon such views will be lost to us forever. And it’s not just about stars. “We also need darkness to create. Just think of all the writers, musicians and painters inspired by the starry skies,” says Bogard in his TEDx Talk. He shows the audience Van Gogh’s painting Starry Night. “Van Gogh knew the night we don’t know,” he says.

“At present I absolutely want to paint a starry sky. It often seems to me that night is still more richly coloured than the day; having hues of the most intense violets, blues and greens. If only you pay attention to it you will see that certain stars are lemon-yellow, others pink or a green, blue and forget-me-not brilliance,” wrote Van Gogh in a letter to his sister Wilhelmina. Bogard shows us how the artist’s work would look today: a light-polluted sky illuminated by a rusty glow, a landscape dotted with brown and amber lights. This painting shows us what already has been lost – and there’s still more at stake.

“For centuries, humans have looked up into the sky and wondered what our place is in the Universe. This experience has inspired our spirituality, religion and mythologies. Just our Galaxy alone – the Milky Way – is home to billions of stars, and the Universe is made of billions of galaxies just like this one. The sight of the starry sky lets us face this infinity, feel humbled by it, but it also helps us realize the miracle our existence on Earth is,” says Bogard. “What happens to us when we can no longer experience it?”


Translated from the Polish by Aga Zano

Also read:

Written in Sunlight
Collection C.H. Florence – Leila et Silvia Florence/Jorge Bastos/motivo, São Paulo

Written in Sunlight

The Curious Life of Hércules Florence
Katarzyna Sroczyńska

He invented photography before Daguerre. He travelled across the Amazon jungle, found a way to document the songs of birds without audio recording, and reproduced political pamphlets without the aid of a printing press. And yet, he was forgotten by the world for over a century.

“I am certain that printing using sunlight will be possible in the future,” Florence noted on 15th January 1833. The French inventor was in his late twenties. He was sitting at his desk in a picturesque Brazilian fazenda in São Carlos, a small town with a population of several thousand, 96 kilometres north of São Paulo. The summer was in full bloom. It was a time when many Europeans were trying to capture the light of the sun on paper, among them the painter Louis Jacques Daguerre. How come everyone knows Daguerre’s name and almost nobody has heard of Hércules Florence, even though he was the first to harness the sunlight? It was the surrealist artist André Breton who wrote that: “The greatest weakness of contemporary thought seems to lie in the extravagant overstatement of the known versus what is left to know.” Hércules Florence would probably agree.

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