Interviewees:
Chris Kyba, physicist and light pollution detective, Ruhr University Bochum
Jana Eccard, animal ecologist, University of Potsdam
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Transcript:
SFX Chris/Kathleen
Chris: No, this is, the this is the problem light.
Kathleen: Oh…
Chris: There is also that other little light there.
Kathleen: So, tell me, what is so bad about this light?
Chris: So, we've just come to an apartment building. There's an entrance to the apartment building. And above it, there's an LED that's not shielded at all. It's very glaring, straight, shining straight into our eyes.
And that doesn't actually allow you to find your way so well because it's so bright.
Kathleen: That’s Dr. Chris Kyba.
Chris: So, we're going to go up and see whether they have a motion sensor.
Kathleen: He’s really into outdoor lighting.
Chris: Ah, ok it came on.
Chris: So, you can actually see where your keyhole is, because there's another light that's activated by motion sensor, but there are many examples where you have a bright light like that, that you're coming up to your house and then you can't actually see where you want to stick your key into the door.
Kathleen: He’s a physicist by day. And a light pollution detective by night.
Chris: So, this light over top of the doorway shining straight downwards is doing a lot more for us than that light that was shining sideways.
Kathleen: That light only seems to be illuminating the trash cans.
Chris: (laughs)
Kathleen: I’ve asked Chris to show me around Cologne, one of Germany’s brightest cities.
Chris: That's the thing. It's just shining sideways, right. So, you can actually, if you. If you can manage to look towards it. You see that those lights aren't directed at all and almost half of the light is actually going up into the atmosphere where it's not needed.
Kathleen: A few years ago, the city of Cologne wanted to find out where light pollution was worst. Chris was part of the team enlisted to help figure this out.
After talking to Chris for a few minutes, it becomes clear: no light escapes his notice.
Chris: It's really funny actually. My wife is always laughing because when we're going for walks on the daytime, I'm pointing out the lights that I can see that I know will turn on at night. Which ones are good, which ones are bad.
… when it comes to artificial lights, as far as Chris is concerned, less is more. Much, much less. Because too much light is changing “night life” on earth – quite literally the life of animals and insects that thrive in the dark.
So, I’ve asked Chris to go on a night walk – to see this issue through his eyes.
I’m Kathleen Schuster.
Kathleen: OK, let's move on to other bad lights.
Chris: Alright.
Kathleen: Chris works at a university about an hour north of here in a city called Bochum. Neither of knows our way around Cologne. But luckily streetlights tend to be pretty easy to find.
Chris: So the light we're looking at here it kind of has a bit of a dip down in the glass underneath the light and that's there in order to spread the light out more. But it's problematic because it means that some of the light will end up going up into the sky.
Kathleen: Chris didn’t really start paying close attention to lighting until the early 2010s. He’d been researching elementary particles in Canada. And then when he moved to Berlin and applied for a job researching carbon fluxes, he accidentally got invited to the wrong interview – for a job researching light pollution. Which he ended up getting.
Chris: “The problem is if you have a pole like this…”
Recently he won a citizen science research award in Germany for a worldwide study showing how, from 2011 to 2022, it became harder for people across the globe to see the stars … because artificial lighting has brightened the night sky by up to 10 percent.
Kathleen: It seems like there are, you know, different kind of…
Chris: … different colors, yeah
Kathleen: …street lights. So, there's one where we're walking that are more like orange, and then the ones for the different colors cars are brighter yellow.
Chris: So, the orange lights that you see around cities are usually high pressure sodium, sometimes low pressure sodium, but that's much less common. Those are all being phased out around the whole world in favor of LED's.
These lights we're going to see, we're going to test in a second to see whether or not they're LED or whether they are fluorescent. Fluorescent lights were not used very much in the United States, but in Germany they're used quite a bit. So, it’s a white light from office buildings, for example.
So, let's do this test.
Kathleen: So, what is it you’re holding up there?
Chris: This this is called a diffraction grading. It's basically a series of really really tiny threads and it splits light into its spectrum so that we can see not just the color that it seems orange to us, but rather the different parts of the spectrum. And when we hold it up to our eye and don't look directly at the light, but off to the side, what we see is a series of lines
Kathleen: Chris is holding up something that looks like a small slide, like for a film projector. Except instead of dark film, it’s see-through.
Chris: This will be a good one…
and what appears is similar to the spectrum of light created by a prism.
Chris: … should get quite close. And you see all those lines, floating above?
Kathleen: Ok, so it's kind of like these, like almost like a vertical rainbow.
Chris: Exactly.
Kathleen: OK. So, it's like at the top, like a streak of red and then orange yellow…
Chris: But there's a bunch of like dots, right? It's like little pearls, kind of?
Kathleen: Yeah, exactly, there's more color, just like a dot of color, uh huh?
Chris: Now we're going to look over here at these white lights, we'll look underneath, ah ha, you want to describe what you see?
Kathleen: Ah, so they're the dots are gone. So, it's just a straight line, just like a straight vertical line that looks like a rainbow.
Chris: But one part of the rainbow is a little bit missing, right? It's darker than the other part?
Kathleen: It all kind of slides together much more. It's like red, almost red to yellow, very little orange and then green and there's less gradient between the green and the like violet.
Chris: There's kind of there's kind of a dark spot between the green and the blue right?
Kathleen. Yeah, yeah.
Chris: So, this is an LED. It's a white LED. The way white LEDs work as they start on the inside with a blue LED and then they use a coating to make that light have longer wavelengths and it all adds up together to be white.
And the amount that you convert that blue into the longer wavelengths changes what we call the color temperature of the light. So how cold or how warm …
Chris: … it feels.
The more you take the blue out, the warmer the light feels. And in general the better it is for the environment.
Kathleen: Light is made up of different colors: red, orange, yellow, green, blue, indigo, and violet.
The sky appears blue because blue light waves are short – and can be scattered more easily by tiny air molecules.
Blue light helps regulate circadian rhythms in us humans. And also in animals, insects and even plants.
This is where LEDs come in. About 20% of global energy consumption goes to illuminating our streets, our homes, and everything else that we want to see clearly at nighttime. That translates to roughly 5% of global greenhouse emissions.
And this has made LEDs an attractive way to reduce emissions because they’re more efficient, and tend to be cheaper. But it also means more blue light – and the question of how much more is really hard to answer.
By some estimations, light pollution has gone up by at least 49% since the early 90s. And one study argues that this number might even be as high as 400% in some parts of the world…but it’s hard to say because not all satellites can detect the blue wavelengths emitted by LED lights. And the ones that can don’t take images often enough for scientists to put together a good timeline.
Chris: Before you install a light the question should be who is it for? And if it's for somebody who comes very infrequently, then having a timer or using motion sensors might be a really good approach. If it's in a very high traffic area, then maybe it makes sense to leave on all night. There's no One answer for exactly what you should do. It's very context dependent, but it always should start with this question. Who is the light for and what do they need?
Kathleen: Ok, Let’s keep walking.
Kathleen: We stumble upon one of the Cologne’s darkest corners … a park
… right in the middle of it all.
Kathleen: There's a cyclist coming across the lawn and I feel like that light is just going straight into my eyes. (both laugh)
But you know, looking up, I was trying to see if we could actually see any stars from here.
Chris: It's cloudy. We would be able to see stars, so.
Kathleen: There is a lot of sky glow.
Chris: Yeah, well, that this is how we we're actually seeing. It's not the light coming from the sides of the park that's allowing us to see things. It's the glow of the sky itself because of all the artificial light going up and coming down. So, on a clear night, we would actually probably be able to see a little bit less well than today.
But even still, sky glow is very, very bright compared to starlight and human beings in open areas can get around by starlight, right?
Kathleen: Europe has some of the worst light pollution in the world.
Cologne lies in heavily populated urban corridor in Germany. From here the Milky Way is no longer visible – and this problem is similarly bad among its European neighbors. It would take traveling hundreds of kilometers northwest to Scotland or south to the island of Corsica to escape it.
Skyglow is part of this problem –and when it’s cloudy, the skies can brighten up to 10 times more.
Chris: Can you tell that? OK, we can't. Can you tell what color that bag?
Kathleen: I would have said pink, but I don't know how we can confirm it's too dark.
Chris: OK. Yeah, it's too dark. OK, so I want to tell you something about moonlight.
Kathleen: Yeah, tell me about moonlight…on this on this night where we can't see the moon at all.
Chris: (laughs) [....] So, if you go out on a night with full moonlight and take a book with you and see if you can read it. You might just be barely able to. If the moon is not quite full, you won't be able to read it. You'll feel like you should be able to because you go outside and you'll say everything seems so bright.
But you're seeing then with the rods in your eyes and not the cones and the cones in the in the central fovea are what we use to read. We use really the very center of our eyes to read, and not the outer parts. And so we have this impression that we should be able to read because we can see everything, everything so well.
But reading requires that color vision, and it's not bright enough for the color vision to function at night, and so it's really kind of surprising. But if you have a night where the moon is all the way full, you'll notice that actually you are start (sic) to be able to see a few colors, especially red, becomes quite obvious.
And you are if you have an impaired vision able to actually read text, that's sort of a normal font size.
Kathleen: You were part of a research project to do with light pollution in Cologne. Could you show me on your phone those pictures that you brought with you?
Chris: One which one should we look at?
Kathleen: Oh, hold on. My eyes have to adjust for a second, hold on. OK, so tell me. Tell me again what was the research that you guys were helping conduct?
Chris: So, the environmental agency in Cologne was interested in understanding what the status quo was with lighting in Cologne. So they got us to fly over the city and take thousands of pictures and stitch them together into a giant map that shows how much light is going upwards in all the different parts of the city, and we did this with a regular camera with red, green and blue, but we also used an infrared camera and an ultraviolet camera to get a sense over the broader spectrum because for a lot of organisms, they're able to see into the near infrared or in the ultraviolet.
Kathleen: OK. And so, you have kind of like a GIF on your phone where we can see different streets lighting up. So, what exactly are we seeing here?
Chris: So, what we're seeing here is I made an animation to switch between the visible picture and the infrared picture and then back to the visible and then to the ultraviolet. Because the ultraviolet is so infrequent, if you just have the map by itself, it's just a bunch of dots and you can't really place it in context. So that's why I like to have the visible picture there as well.
One moment while we bring the picture back. So when we see this switch from the visible to the infrared
Kathleen: What they found was that over a third of the city’s light came from streets, parking and residential areas. Buildings were generally about 70% brighter than the city average.
The worst type of light for insects– UV light – tended to come from hotels, restaurants and churches.
Kathleen: Ok, just kind of in broad strokes, what exactly is the problem with light pollution when it comes to our environment?
Chris: So when life evolved, it had a regular switch from daytime to nighttime, and that was really important for early life to adapt to that. And for hundreds of millions of years, we had sort of the same conditions all the time throughout the months and throughout the seasons, and now all of a sudden, the light environment at night is completely different from the way it was during this entire evolutionary period. And so that really throws a lot of organisms for a loop because it's just not what they expect.
And their body is expecting something different and could be fooled by this light that's there at the wrong time or in the wrong place. And so the really classic example of this, of course, is moths attracted to a flame. That flame isn't supposed to be there in the natural environment. […]
And that means that they are not looking for food. They are not looking for mates, they're sort of stuck and in the worst case, they become exhausted and die and sort of remove that biomass from the ecosystem.
Kathleen: Chris has been working together with an animal ecologist named Dr. Jana Eccard on these questions of light pollution and biodiversity.
Jana works at the University of Potsdam outside of Berlin and says if you want to know how we’re impacting insects, just look at your regular black beetle.
Jana Eccard: My interest in beetles was triggered with these little LED garden lights. They are put to places where you, you know you need a bit light to see the step in your garden or you want to illuminate the path. And these are usually these little garden lights that that, that, that illuminate the ground. And I was wondering what all these animals that walk on the ground on the surface of the ground whether or not they are affected by this small garden lights.
And until recently the gardens and the parks in our cities were the dark refuges for all this little night creatures. And now suddenly you could buy this LED lights everywhere and people just put them out everywhere. If you now walk through Berlin and look at the gardens, they look completely different. They have all these little light sources everywhere. They're rare and this is a new threat to all the animals on the ground.
These predatory ground beetles are a group that is very well researched because for decades they have been indicated species for habitat quality, for habitat moisture, for pollution.
Kathleen: Jana and her team placed solar-powered LED garden lamps in a Dark Sky Reserve outside Berlin to see how beetles would respond. They found two main results: One, there were some beetles that gathered around the light and got stuck.
This a common problem with insects and means that they’re more likely to be eaten by spiders, toads and bats.
The other outcome was that some of the beetles avoided the light altogether and reduced their nighttime activity. And in both cases, this echoes a general concern that distracted insects stop doing what they do best: foraging, and mating. And this can ultimately reduce their population size – and have widespread knock-on effects.
Jana: Because they eat pests, they eat caterpillars, they eat all kinds of other herbivores, beetles or other beetles that eat plants. So they are active at night and eat lots of things that you don't want to have in your garden. (laughs) So that will could be a straight impact because the food chain has changed
and in this case the predator, the group of predators, the group of animals that control other animals is affected.
Kathleen: Another knock-on effect that researchers want to prevent is the impact on nocturnal pollinators, like moths. Authors of a recent study from the UK in 2020 have pointed out, moths that pollinate at night could help stabilize agricultural ecosystems at a time when daytime pollinators, like bees, are dying out.
Jana says animals farther up the food chain, like voles, are being affected, too. If you need something to brighten your day, do yourself and google this animal. It’s like a mouse but cuter. That’s vole. V-O-L-E.
One impact she and her team found was that artificial light – and skyglow -- made the voles shift their foraging activities from the night to the daytime.
Jana: We don't see that much biodiversity partly because a huge proportion of biodiversity is active at night and we don't see it. So some people say more than 60% of the insects are nocturnal.
So you find different figures 50,60,70, but it's a quite a proportion and that proportion we don't see.
So, we underestimate activity of nocturnal animal animals. We underestimate how important they are. We underestimate their biodiversity and we massively disturb it with artificial light at night.
Kathleen: The park Chris and I are walking through is almost entirely absent of any lights.
Kathleen: Would you say this is a very good example of what things should be like?
Chris: So, when we think about urban planning, we really need to think holistically about everyone. The people who live there and the environment. In Germany, it's very typical that most of the parks are not illuminated and these are very important refuges for urban animals.
In certain cases, it may make sense if you have a very high use of people and you want to encourage more people to use a park, that you illuminate that park, but in the sort of holistic city planning, you don't illuminate every park. And in that way you do have areas where people who are more concerned about lighting have a way to go to the park at night, but you also preserve. This area for nature, but also for the enjoyment of people who enjoy being out in the dark.
Chris: There's this enjoyment of the night that is missing in a lot of places that I feel in Germany is a lot easier to find actually than in a lot of other wealthy countries.
Kathleen: You know, I'm really tempted to go up to one of these people who are who are walking through the park like, no, I think I would scare them half to death if I came out of nowhere with the microphone. No.
Chris: (laughs) Yeah, you should go for it. You should go for it.
Kathleen: (laughs) No, I think it'll be fine.
Chris: No, we're just standing there talking. I can do the excuse me.
Kathleen: No, you know, no problem. No, no, that's.
Chris: If we just go on the path as people walk by.
Kathleen: No, that's OK, I think. Yeah. Yeah. No, I really don't want to scare them.
Chris: What I would love though, is just to check out if we can just for fun what the gender breakdown of people is, because what I will bet you is that there are a bunch of women also using the park, even though it's not illuminated.
Kathleen: OK, I'll, I'll take that bet. I'll take that bet OK let’s see.
Chris: Hard to tell. […]
Chris: Would you walk through a park like this in Germany For no?
Kathleen: By myself? No way. No, no, no. I would. I
Kathleen: Well, let's say we've seen a few women walk by. We've seen, we saw mother and daughter but the joggers I think, have all been men and on bikes I I would be willing to say on bikes it would be not that big of a difference because you're on a bike. You can get away.
Kathleen: Two women running together, though yes, strength in numbers.
Chris: But also with no headlight, so they.
Kathleen: Yeah, but I think because they're together, that would.
Chris: Be my best. No, of course. No. Yeah. Yeah, but the point is just this one that there's this common understanding that if an area is unlit, people will fall down and die. And I've even seen this written in in German news media before that, that a that a landowner was concerned that someone might fall and trip and die.
The truth is, if you're in an area that's not lit, and especially if you've given yourself a moment to adapt, there's so much light simply from the sky itself that you can get around relatively safely as long as you have, as long as you don't have a vision impairment.
Kathleen: So can do you know where we are? And we are like down here somewhere in this in the.
Kathleen: But yeah, but I'm also wondering in this environment, so you know it's nice and dark here, but as you can hear in the background, there's a ton of traffic. We're in one of the biggest traffic rings in the city and so there's lots of light from that. And then in the distance we see we see more light.
Does it make that big of a difference if there are small pockets of space that are kind of more protective for biodiversity?
Or is it kind of like, well, there's such a large-scale problem this is you know just a drop in the bucket?
Chris: No, I think it really does matter actually for the parks to be not illuminated. But the distance that some insects and other organisms travel is not really large.
And if you're thinking, for example, also of a bird that nests in a in a nest, they built in the tree, it's going to be a really big difference whether that light is like here. In our case, it's maybe 50 or 100 meters away, to if the light is right in the park, in terms of you know how they sleep in their nest.
So having these pockets of darkness, I think really is actually important for biodiversity. And in Europe, there's a little bit of a movement to try to link these dark things in the same way that we try to create green corridors for animals to navigate through the environment, also to create dark corridors so that animals that are active at night time have a way to move around through the environment.
For bats for example, it's really important to have these linkages between where they sleep and where they eat. And so these kinds of parks and things can become part of a dark corridor for that perspective.
Kathleen: Eventually the bright lights of the city draw us back in.
SFX Kathleen “We have to cross this street while we can”
Chris wants to check out an LED hotspot he saw in his aerial photos. It’s a soccer field. But whether the lighting is good or bad remains to be seen.
Chris: One of the things that we see here is that we're standing almost directly beneath one of the lights.
And it is not glaring and we're standing in a really moderate amount of light because this is a as a highly asymmetric light. It's shining its light on the field and it is trying to avoid shining it onto the surrounding areas.
Kathleen: Yeah, it's interesting looking up at it because it looks like it has…
Chris: Shields.
Kathleen: Are those? Yeah, like four metal shields on each side. And so you can look at it, of course should look straight at it, but it's not. It's not completely blinding. That's true. I wouldn't. I don't think I would have noticed that if you hadn't said anything.
But sports lighting can be really, really problematic, especially for neighbors, even up to a kilometer away. It can be really, really problematic if you're not maintaining the light in the sports area. So, this is really an example of like, this is the kind of world we're imagining. You still have the illumination. You're still able to use the sports field. But you're really reducing the amount of light that's going into the environment.
Kathleen: We head back to the quieter street where we began this episode to track down one last light, when a different light altogether catches our attention.
Kathleen: He’s got somewhere he wants to be.
Chris: Yeah
Kathleen: OK, so you want you wanted to check out.
Chris: Whether we find some ultraviolet light here because.
Kathleen: Oh, hey, I see the moon, do you?
Chris: Oh yeah, nice.
Kathleen: It's pretty… actually it looks so strange because it looks. It's mostly behind the clouds. Yeah, but the clouds around it aren't really illuminated. It's just this fuzzy bright spot in the bright sky. Watch out for the glass.
Chris: So, the funny thing is, if we were in a natural area, with that moon there like that. Even though it's cloudy, we would be able to see quite well once we let our eyes adapt.
And so, there's this great quote from an article about industrialization. They talked about the mayor of Bochum Max Greve. He was the mayor of both him for 30 years during industrialization and when the city got its first street lighting. And then what this historian said is he fought the rest of his life against the absurd modernism that would leave the lights on even when the moon was shining.
And that's so impossible for us to imagine now as city dwellers in the 21st century. That you would you know, turn lights on and off based on the moon, but that was actually really common practice back when people were really concerned about their energy use because the energy was so expensive.
Kathleen: Well, it's very interesting. Makes complete sense, but I don't think anybody would think to do something like that also because our, yeah, our lives just are designed completely differently.
Chris: This is the thing that that can be, for example, not in the city center necessarily, but if you're talking about a German village or something way on the suburb edges of the city.
I think it's something that that could potentially, conceivably come back because if you do experience moonlight, you realize that it's actually a wonderful light source because it's so uniform in comparison to our current St. lighting where we have bright patches and dark patches and glaring things.
Chris: Sorry, you’re going to get run over here..
Kathleen: But I think I mean thinking about, you know, what could a city look like with less lighting or a different kind of lighting? It's kind of in contrast to what we think of as a modern city, which is, you know, city lights. Right? And the cities that never sleep and that whole thing it's kind of an odd. It's kind of odd to think about reducing the amount of light.
Chris: So, no one actually knows how bright anything is. You actually need the luminance meter if you want to measure how much light there is. And so in a place like Times Square, there are actually clear rules about how bright the signs are allowed to be. It's not just anything goes.
Yeah. So ideally when we're looking at a city from far away, this image of the twinkling lights of the city is not going to be there anymore because the lights going to stay inside the city, it's not going to reach the hills far away anymore.
But for the people who are in the city, it shouldn't seem dark. The whole idea is that we're trying to create spaces that work well for people, while not illuminating the places where the nature is.
And so, in your city center, you should still be able to have advertisements. You should still have sidewalks that you can walk on safely, but the idea is to keep that light there and not let it get into the surrounding areas.
So, it is true cities sometimes that there is that attraction of seeing the twinkling lights from far away.
But I'm not sure we want to buy that at the cost that it has to the environment when it is possible to still have what we really need, which is that we can get around in the city safely at the cost of losing this, like twinkly lights far away.
Kathleen: We’ll be right back with a few tips for outdoor lighting.
PROMO
Kathleen: Light pollution impacts at least 80% of the world’s population. In Europe, it’s nearly 100%.
And while, as Chris pointed out in this episode, most of our lighting problems are at a large scale beyond our individual choices, there are still a few things we can do to help the ecosystem in our own backyards.
The first question you should ask yourself when using an outdoor light at night is: “What is this light actually for?” Is it for safety? Is it for decoration? What’s its purpose?
Two, if it’s a light you absolutely need, can it be put on a timer? Or installed with a motion sensor? Could it be dimmed? Cheap LEDs tend to be problematic because of the intense blue light they give off, but there are some higher quality options on the market, too.
Three, is the light illuminating a larger area than is necessary? For example, is it going up straight into the atmosphere, or going sideways for no particular reason? The more you can direct your light, the better.
And finally can you create safe havens in your backyard or garden to shield animals and insects from the light? Some researchers have suggested that trees, for example, can provide an island of shade for creatures that live in the dark. The same goes for ponds or any other body of water you might have in your backyard. Keep the light off of that too if you can.
Today’s episode of Living Planet was written and produced by me, Kathleen Schuster and edited by Neil King. We’re going to be coming out with a follow up to this episode in a few weeks, so make sure to hit subscribe on Apple, Spotify or wherever you get your podcasts.
You can listen to Living Planet wherever you get podcasts. Did you have any questions or comments about this episode? Let us know! Our email address is [email protected].
Living Planet is produced by DW in Bonn, Germany.