Responses to light pollution: The infernal glow of an eco-friendly society

If you’ve ever moved far outside of the latitude to which you’re accustomed, you know how disorienting it can be to have day length change. My move to the British Isles had me confronting both the extremely long nights of a northern winter, and the surreal experience of realizing at 9pm that it was still about an hour before “night” started. I can only imagine how disorienting artificial light can be to creatures without the capacity to understand what’s going on.

The image shows a Manx Shearwater crouching on the ground. It's a bird with a long beak, hooked at the end, and tubular nostrils characteristic of its order. The back head, and beak are a dark slate gray, with a white throat and belly.

Photo by Martin Reith

When Tegan and I were working on our doomed application to live on the Isle of Rum, we were looking at even longer nights over the winter, and a community that had zero light pollution. As one of the world’s major breeding sites for the Manx Shearwater, every home has blackout curtains, so that the juveniles won’t get confused by artificial light, and head towards the village rather than down to the sea. There are also no street lights, or any other lights at night. One of the things I was looking forward to, had we been allowed to live there, was the night sky, when the weather allowed it to be visible. If you’ve never been far enough away from artificial light sources to see what the sky looks like without all that interference, I very much hope you’re able to experience that some day.

There are a lot of reasons why it would be good for our ecosystems to cut down on light pollution, but I think it’s also important to acknowledge that the bright lights of cities aren’t there just because of convenience, neglect, or aesthetic reasons. Places with high concentrations of people tend to have more crime, and crime is more likely to happen under cover of darkness. When I was in college, I attended a seminar on sexual assault in which we were asked to say whether we felt safe walking across campus at night, and how that feeling changed if one of the street lamps was out. The results were pretty consistent – most female-presenting people were not remotely comfortable crossing campus in the dark. That’s not an irrational fear, and it’s not something that we should discount in thinking about how to re-imagine our use of light.

It’s also important to note that not all places are going to have the same requirements, and those requirements are likely to change depending on the season. It may be that the ban on artificial light isn’t necessary outside of the month or two during which juvenile Shearwaters are heading to sea, for example. There may also be places where the potential for ecological disturbance is low enough that there’s no need for change beyond energy conservation.

Image shows a suburban street, wet from recent rain, and illuminated by red street lamps. There's some white and yellow light coming from the houses, but the dominant color, aside from the dark blue of the night sky, is the red from the street lamps

And in some cases, it may be that the only change needed is in the color of outdoor lighting. Enter the town of Zuidhoek-Nieuwkoop, Netherlands, that has installed red street lights, to be more hospitable to bats.

It turns out that while most insectivorous bat species don’t care a whole lot about artificial lights, there are some that care a great deal, and that face serious problems from the fact that not only do they need to go out of their way to avoid most lights, their prey tends to have the opposite reaction. That means that for these species, there’s actually less food they can access, even with stable insect populations, as the insects congregate around the lights the bats have to avoid. Red lights solve both of these problems:

Artificial light at night can have a disruptive effect on bats, but not if the light is red. Switching to red light may therefore limit or prevent habitat loss for rare, light-shy bat species. The latest issue of Proceedings of the Royal Society B publishes results from five years of pioneering research led by the Netherlands Institute of Ecology (NIOO-KNAW).
It’s the first time researchers have succeeded in measuring the effects of light with different spectra on the activity of slow-flying, light-shy bats in their foraging habitat. “We’ve found these bats to be equally active in red light and darkness,” says principal researcher Kamiel Spoelstra. “White and green light, on the other hand, substantially reduce the bats’ level of activity.”

The effect of red light on more common bat species such as the pipistrelle is reduced as well. Unlike a strong increase in activity of this species in white and green light, the activity in red light is comparable to darkness. This is caused by the strong attraction of insects to white and green (and not red) light. Pipistrelles opportunistically feed on these accumulated insects.

Real-life conditions

“The lack of effect of red light on both the rarer, light-shy species and the more common non-light-shy bats,” concludes Spoelstra, “opens up possibilities for limiting the disruption caused by external, artificial lighting in natural areas, in situations where having light is considered desirable.”

I don’t know if there’s any research into how the color of street lights affects safety for humans, but this is a great example of how we can put our understanding of animal behavior and physiology to use, and provide a service for humans – illuminated streets at night – that won’t interfere with the local wildlife, because the animals that might care about artificial light can’t detect those wavelengths. As always, it’s unlikely there’s ever going to be a “perfect” solution – perfection is more of an aspirational concept than an achievable goal – but there are many changes available that will help a lot, without causing us any real harm. It might be strange live somewhere that glows red at night, or to see the white wind turbines we’re used to replaced by purple ones, but we live in a world that’s increasingly alien to the on e on which we involved. I, for one, rejoice at the notion of building a new society that embraces that strangeness.

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  1. Pierce R. Butler says

    Damn moonbat ecomaniacs want to turn the whole world into a red-light district!


  2. Art says

    Back in the 70s the navy kept warehouses in some fairly remote places in Virginia. It wasn’t like it was really valuable stuff. During one of the many budget cuts the active policing protecting the area was discontinued. So the locals, knowing that while it was well lit, but unpatrolled, and that your chances of getting busted were essentially nil took to getting drunk and breaking in. Anything for a thrill. As I said, the stuff was mostly big, bulky, and rather low value if measured in dollars per pound. Still regulation say it has to be kept locked up so the major cost of any break-in was repairing doors and replacing locks.

    This went on for a while. The navy kept trying to get money for security guards or to get local police to patrol. It was pretty much out of their main area so the local PD would roll through for a while but after a week or so other issues would take president. So, the break-ins kept happening.

    At least they did until somebody working security for the navy got smart. Instead of having the place well lit and hoping this would scare off intruders, who well knew there was no law around, they simply turned off all the lights. Large Federal facilities without lights are a bit scary, like something out of a monster movie. Of course this helped but the real benefit was that it made the place dead simple to look after. The local police simply had to drive up one of the local hills and look. If they saw any lights they knew there was a problem.

    The locals didn’t think stumbling around in the dark, or facing federal charges, was fun and found other ways to get their thrills.

    As for light pollution: IMHO there is no reason for there to be such waste. As an electrician I’ve installed a lot of lights. Typically less is more. A 40w equivalent LED, around 7w, will light up the side of a house. No you won’t be reading the Financial page at 2 AM out on your lawn but it is more than enough to see if an intruder is on your lawn or messing with your car.

    Second: fixtures are not all the same. Spend some extra time and ones that send the light downward are out there. Any light sent upward is wasted.

    Third: Electricity is not free. Lower wattage fixtures use less power. I recently replaced eight 150w floodlights ( about $52/mo) with eight 13w LED floods (about $4.50/mo). The lady of the house likes the mellower tone. She said it look more like a home and less like a prison. Most people could have done the job themselves but they weren’t enthusiastic about the ladder. It took me an hour. Simple: unscrew halogen flood – screw in LED flood.

  3. publicola says

    Maybe, someday, city kids will be able to see the Milky Way from their front porch.

  4. StevoR says

    @ ^ publicola :Hope so though I’d settle for most stars over 3rd magnitude being visible given how utterly horribly washed out and light polluted most modern global cities are.

    Incidentally, love this red light solution and wish mor epalces would adopt it including here. Thanks for this news item and idea, Abe Drayton – shared.

  5. says

    crime is more likely to happen under cover of darkness.

    Is there scientific research to back up this claim? Studies about cities that either reduced or increased illumination in some area with crime rate either increasing or decreasing afterwards? I would be less convinced if there’s research showing correlation that parts of cities that have more light also have less crime, because places inhabited by rich people are simply better lit in general, and socioeconomic factors affect both crime rate as well as policing (cops are more likely to patrol certain places and record whatever happens there, while in other places crimes remain unrecorded).

    Anyway, my instinct tells me that a claim “more light equals less crime” sounds too simple and might be on par with the idea that “broken windows equal more crime.”

    Maybe light affects different crimes differently? Does more light have the same effect or car thefts, mugging cases, and burglaries?

    Maybe more light has different effects in densely populated cities versus small towns?

    Maybe more light affects crime only until a certain threshold is reached, after which installing even more lights has zero effect?

    Maybe lights triggered by motion sensors work just as well/even better as installing bright lights everywhere?

    Maybe light has no effect on some crimes and it is a lack of witnesses that matters for criminals?

    Right now I’m coming up with random ideas. It seems unlikely for me that the relationship between light and crime can be so simple as “more light equals less crime,” which just sounds like an attempt to simplify a complex problem. I probably should go and do some research right now, but (1) I’m somewhat busy right now; (2) since you wrote about light pollution, maybe you already know about relevant studies and it doesn’t hurt asking.

    When I was in college, I attended a seminar on sexual assault in which we were asked to say whether we felt safe walking across campus at night, and how that feeling changed if one of the street lamps was out. The results were pretty consistent – most female-presenting people were not remotely comfortable crossing campus in the dark. That’s not an irrational fear, and it’s not something that we should discount in thinking about how to re-imagine our use of light.

    Yes. Definitely. If people feel unsafe leaving their homes after dark, that’s a huge problem.

    There’s also a practical problem. A decade ago I was walking in a dimly lit place after rain. I accidentally stepped into a somewhat deep water-filled hole in the pavement. It was so unpleasant that I still remember that incident.

    Thus we need street lights. But we should determine the minimum amount of light necessary for people to feel safe and comfortable and stop installing more light than necessary.

    In addition, we should stop pointlessly directing light towards the sky.

    Flashes used by photographers are pricey. Doubling the light output of your photo lights is expensive. For location shooting you also need to carry around the extra weight and bulk of more/larger lights. Thus for decades photographers have worked on inventing solutions how to get the greatest amount of usable light with the smallest amount of actual light output. Behold: reflectors.

    Those things actually work. If you need to illuminate only your model, you cover up your light with something reflective and silvery on one side. This way the amount of light that hits your model is much greater compared to what you would get without reflecting, shaping, and directing light.

    I absolutely loathe how most streetlights emit light in all directions and also towards the sky. We do not need to illuminate the sky. We need to only illuminate the street. And we should also stop aiming light directly into people’s windows. Sleeping at night with a streetlight shining into your face sucks. And telling people to just install curtains in their homes is not a solution. To begin with, curtains that completely block all light are niche products that cannot be found in any local store and must be ordered online from abroad (ask me how I know!), moreover, light will still shine around your curtains.

    Besides, our society’s utter refusal to stop illuminating places that don’t need to be illuminated during night (like the sky or my bedroom window) is a huge waste of electricity.

  6. says

    @Marja – thank you for that! I hadn’t considered that, and I should have.

    @Andreas – I couldn’t give you reliable data on that. I’m also not sure how crimes of opportunity using darkness, to whatever degree they exist, would more or less go away with a society that guarantees basic needs.

    The points about directional light and pointless light are well taken.

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