So far, we have put the spotlight on 4 victims of the night – sea turtles, dung beetles, birds, and bats. Despite being nocturnal or exhibiting some nocturnal behaviour, their populations’ survival is at risk at night, where artificial lighting reigns. While this blog covers only a few victims of artificial light pollution at night, there probably exist various undocumented species affected by light pollution, and their long-term ecological impacts are still not yet fully understood. It is in the hope that by engaging more with the lives of animals, the more deeply we witness how interconnected we are with nature – and how to best coexist with it. If light pollution is a product of ignorance, then we need to educate ourselves about it and learn what we must do to alleviate it.

In a research article by Owens et al. (2020), light pollution is argued to be a major factor causing the widespread declines of insect populations. Light pollution was shown to affect the movement, foraging, reproduction, predation of insects, as well as the development of their juveniles (Owens et al., 2020).

Source: Shutterstock

Does this scene above look familiar to you? These are moths that were attracted to an artificial light source. According to Owens, insects attracted to artificial light sources have a high death rate. Some insects, like the dung beetle Scarabaeus satyrus, wasps and dragonflies, require visual cue from celestial light sources for orientation. Insects are found to suffer from a more limited foraging area due to the effects of artificial light at night, with a higher risk of predation. Moreover, while it is more commonly known that light pollution leads to the suppression of melatonin production and disrupts our circadian rhythms, a similar thing happens to insects too. The resultant desynchronization of insects from their environment can cause imbalances in its population and the food chain (Owens et al., 2020).

Half of all insects are nocturnal – could the scale of destruction be larger than we thought? When reminded of insects, most of us cringe and think of the sight of cockroaches scurrying about in the kitchen. However, insects encompass a wide range of orders, families, and species, many of which are important pollinators and play a significant role in the food chain. Did you know that the global insect population has been declining? Some studies predict that up to 40% of insects could go extinct in the next few decades (Owens et al., 2020)! We need insects to survive, and light pollution is inadvertently compromising our own survival. In the next section of this blog, we are going to focus on solutions –  what creative solutions have been employed so far to counter light pollution, and is there a future for a light-pollution free world?

Source:

Owens, A.C., Cochard, P., Durrant, J., Farnworth, B., Perkin, E.K. and Seymoure, B., 2020. Light pollution is a driver of insect declines. Biological Conservation, 241, p.108259.

Hi everyone! Welcome back to the blog! Another one of our nocturnal friends, urban bats, are found to be negatively affected by light pollution.

Rhinolophus hipposideros. Photo from Bats Life

In a journal article by Stone, Jones, and Harris (2015), “Impacts of artificial lighting on bats: A review of challenges and solutions”, it was found that artificial light at night leads to negative implications on bats’ foraging and commuting behaviour.

The disruption of commuting routes can force bats to fly further to reach their foraging grounds, or in some cases, even abandon their roosts. (Stone at al., 2015)  Artificial light at night disturbs the circadian clocks of bats, leading to delayed emergence, causing them to miss the peak in abundance of insects, that occurs at dusk (Stone at al., 2015). Moreover, juvenile bats may be more at risk of predation and collision with vehicles, and have slower growth rates as a result of light pollution (Stone at al., 2015). While some species of fast-flying bats are attracted to street lights due to the abundance of insects around these lights, slow-flying bats avoid street lights due to the higher risk of predation (Stone at al., 2015). Thus, bats populations are at risk of decline with light pollution.

While studies like these do not yet exist in Singapore, it makes me curious as to how bats in Singapore are affected by light pollution. We occasionally see bats scooting around at dusk, as dark silhouettes that quickly dart around the edges of our vision, yet how much do we know about our elusive (animal) urban neighbours? Like what Prof Taylor had said in the lecture on Light Pollution, studies on the ecological impacts on light pollution are still in their early stages, and have great room for discovery.

Source: Stone, E.L., Harris, S. and Jones, G., 2015. Impacts of artificial lighting on bats: a review of challenges and solutions. Mammalian Biology, 80(3), pp.213-219.

Hi everyone!

On the night of 11th of September every year (from dusk to dawn), two strong beams of light are shone onto the sky in New York, near the 9/11 memorial (9/11 Memorial & Museum). This art installation, Tribute in Light, honors those who died from the 9/11 terrorist attack on the World Trade Centre in 2001. However, Tribute in Light also resulted in an unintended consequence – the deaths of thousands of birds every 11th of September.

Perhaps the producers of Tribute in Light were not initially aware that the 11th of September coincides with the migration of birds across New York City. Moreover, most migratory movements are nocturnal (Van Doren et al., 2017)! Just like the dung beetles we discussed in the previous blog post, birds also require visual cues from celestial sources for navigation. Artificial light at night interferes with their ability to navigate well! Furthermore, the disruption to their internal navigational systems could lead to fateful collisions with buildings (Van Doren et al., 2017). In a research study conducted by Van Doren et al., “when the installation was illuminated, birds aggregated in high densities, decreased flight speeds, followed circular flight paths, and vocalized frequently.”

Photo: Van Doren et al., (2017)

What has been done to mitigate the problem? According to the New York Times, “when the number of trapped birds reaches around 1,000, the lights are switched off for 20 minutes to let the birds disperse” (Barnard, 2019). However, while this measure has prevented the deaths of many birds, is it enough? The study by Van Doren et al. also shows that turning off the lights led to a halt in behaviour disruptions. Yet what effects do those “trapped birds” suffer when the light beams are still on? And are there long-term consequences that could bear upon these birds? Could these circular paths taken by the birds also exhaust them of the energy they need to embark on their long-distance migration journeys?

Awareness of light pollution and its effects not just on humans, but on various life forms, goes a long way in ensuring that we make wise choices that will protect our ecosystems and health!

Sources:

Barnard, A. (2019). The 9/11 Tribute Lights are Endangering 160,000 Birds a Year. The New York Times, [online]. Available at https://www.nytimes.com/2019/09/09/nyregion/911-tribute-birds.html

Van Doren, B. et al. (2017). High-intensity urban light installation dramatically alters nocturnal bird migration. PNAS, 114(42), pp. 11175-11180.

Hi everyone! Welcome back to the blog. Apart from the nesting behaviour of sea turtles and the survival of their hatchlings, artificial light pollution also affects the populations of other organisms. Today, we are going to focus on the effects of light pollution on dung beetles.

Photo: Science News

Firstly, what are dung beetles, and why are they so important, if they, well… eat dung? Dung beetles are a family of beetles from the insect order Coleoptera, and consist of thousands of species that are widespread throughout the globe. Dung beetles play an important ecological role as they literally consume and process mammalian faeces. Without the work of dung beetles, our world would be covered in dung! In order to survive and reproduce, dung beetles face the task of rolling the dung balls away from fellow competitors at the dung pile back into their nests, where dung is stored as food. Dung beetles also lay eggs in the dung balls, after which their larvae feed on the contents of the dung ball. However, light pollution interferes with the navigational abilities of dung beetles, which are vital for their survival (Foster, et al., 2019).

Photo: The Blue Beetle

Among nocturnal dung beetle species, the light intensity gradient of the Milky Way, and the patterns of light polarization by the moon are important visual cues for the dung beetles’ navigation. Specifically, the Scarabaeus satyrus (a species of dung beetle native to South Africa) relies on these cues, in order for it to successfully roll its dung ball back to its nest (Dacke, et al., 2013)

Photo: National Geographic

In a study that showed how polarized lunar light at night were important visual cues for dung beetle navigation, the degree of polarization was found to be an important factor in the strength of the visual cue (Foster, J., 2019). However, the degree of polarization can be reduced by light pollution in urban areas, even if the moon was visible from Earth. Moreover, when the bright lights of the city obscure the light from the Milky Way, dung beetles are prevented from navigating effectively with the visual cues.

To many of us city-dwellers, the lives of insects are not so well-known. Yet, a night without light pollution makes a world of a difference to these nocturnal dung beetles. The benefits do not stop here. Think about how the survival of dung beetle populations is also connected to our collective survival – dung beetles play an important role in naturally decomposing waste, and the control of fly populations (Schowalter, 2016). While our dung beetle friends are asking, “where did the stars go?”, maybe we should too.

Sources:

Foster, J., Kirwan, J., El Jundi, B., Smolka, J., Khaldy, L., Baird, E., Byrne, M., Nilsson, D.E., Johnsen, S. and Dacke, M. (2019). Orienting to polarized light at night–matching lunar skylight to performance in a nocturnal beetle. Journal of Experimental Biology, 222(2).

Dacke, M., Baird, E., Byrne, M., Scholtz, C., Warrant, E. (2013). Dung Beetles Use the Milky Way for Orientation. Current Biology, 23.

Schowalter, T. (2016). Chapter 16: Application to Sustainability of Ecosystem Services. In: Schowalter, T., ed., Insect Ecology, 4th ed. London: Academic Press, 541-563.

Sea turtle hatchling, Source: Miami Herald

Hey everyone! Did you know that sea turtles are a victim of light pollution? Sea turtles lay their eggs on beaches, after which baby sea turtles hatch and find their way to the sea. Baby sea turtles rely on the stars’ illumination for navigation, which is reflected by the sea. However, light pollution from the beach disorientates baby sea turtles, leading them to make their way inland instead, where they die getting lost among beachfront properties or getting eaten by land predators! Female sea turtles also often return to the sea without laying their eggs, when light pollution is present at beaches (Sea Turtle Conservancy, 2020).

The presence of unshielded, white artificial lights can take a blow on the already fragile sea turtle population, in which baby sea turtles already have a high mortality rate. Of the hundreds of eggs laid by a female turtle, only less than 0.1% of that number will survive to adulthood, due to predation by animals on the beach (National Geographic, 2019). Moreover, all seven sea turtle species are threatened with extinction (National Geographic, 2019). Apart from light pollution, sea turtles also face a host of other threats such as marine pollution, commercial fishing, illegal harvesting of turtle eggs, and poaching.

While the sheer number of eggs laid by female turtles ensures that a few of the hatchlings survive into adulthood, anthropogenic light pollution threatens to destroy that ecosystem balance. Nevertheless, this predicament is entirely preventable, and success stories have emerged through sea turtle conservation work in Florida. The Sea Turtle Conservancy has helped to retrofit turtle-friendly lighting for over 200 beachfront properties in Florida, where some areas have a 100% drop in disorientation rates (Sea Turtle Conservancy, 2020)!

So, what can we learn from the work of the Sea Turtle Conservancy? This is what they have to say:

1. Keep it low
   

   A light source that is low relative to the ground, Source: Sea Turtle Conservancy

2. Keep it shielded
   

   A shielded light source, Source: Sea Turtle Conservancy

3. Keep it long 
   

   Source: Sea Turtle Conservancy

As we have discussed earlier in the previous blog post, short, blue wavelengths of lights contribute to light pollution and lead to harmful effects on human health. According to the Sea Turtle Conservancy, longer wavelengths of light, starting from 560nm, helps to reduce light pollution!

On many beaches around the world, light pollution has only gotten worse with the rise in tourism and coastal development. Yet, even with tourism, Florida has shown that it is in our ability to save sea turtles by keeping our lights low, shielded and long! We can do better to educate stakeholders and the public on protecting sea turtles from light pollution! May there be many beaches in the future that decide to clean up their act like Florida.

Sources:

National Geographic (2019). Sea Turtles 101. . Available at https://www.youtube.com/watch?v=5Rmv3nliwCs&t=77s&ab_channel=NationalGeographic [Accessed 14 September 2020].

Sea Turtle Conservancy (2020). Guardians of the Night: Reducing Light Pollution on Sea Turtle Nesting Beaches. . Available at https://www.youtube.com/watch?v=R5ID9MU1bCQ&ab_channel=SeaTurtleConservancy [Accessed 14 September 2020].

Hi everyone!

In this post, I am going to continue our debate on the benefits and costs of LEDs. In the previous post, we found that LEDs are celebrated as the most energy-efficient bulbs of all time, and are increasingly used as street lighting by cities. However, what are the hidden costs, behind those bright, white lights?

First, we need to talk about the blue wavelengths of light that LEDs emit. You might probably be familiar with the electromagnetic spectrum as shown in the photo below. See how we can only perceive a small part of that spectrum, called visible light? Different bulbs emit different wavelengths of light. Some wavelengths of light, such as blue/purple light, are short, while redder wavelengths of light are long. While LED lights can be configured to emit warmer or cooler light, most LEDs today emit blue wavelengths of light, which measure around 440-500nm. This has negative consequences on our health, and the environment too!

Photo: Science Struck

Coinciding with the blue wavelength of light emitted by LEDs, is also the suppression of melatonin production in our bodies. The suppression of melatonin production disrupts our natural circadian rhythms, leading to higher risks of insomnia, stress, illness and even cancer, as reported by a study in the Journal of Environmental Management. (Did you know that your phones, tablets, and computers also emit blue light? Could that also be linked to how we city folks are sleeping later at night, given how long we spend looking at our screens?) Now that’s worrying.

Photo: Getty Images

Photo: Blue Light Exposed

The diagram below compares the Kelvin colour temperature of different forms of lighting. Compared to other forms of lighting such as metal halide, high-pressure sodium and incandescent bulbs, LEDs emit the bluest light. As much of our street lighting is being converted to LEDs, light pollution is set to increase. The study also reported that blue light is more readily scattered in the atmosphere than red or green light, and that LEDs could produce a growth of artificial night sky brightness by 2.5-5 times, as perceived by the dark adapted human eye.

Photo: LED Spot

So what can we do to prevent the harmful effects of LED lighting on light pollution, while still enjoying the energy-efficient benefits LEDs bring? Recommendations from the study suggest that we use less polluting, warmer LEDs with no blue emissions. Legislation to ban outdoor emissions of light at wavelengths shorter than 540nm will also go a long way in reducing the level of light pollution by street lighting, in addition to other practices such as shielding and eliminating over-lighting. So, know your LEDs folks!

Source: Fabio Falchi et al. (2011) ‘Limiting the impact of light pollution on human health, environment and stellar visibility’, Journal of Environmental Management 92, p.2714-2722

Photo: The Economic Times

Hello dear friends! Earlier in my previous post, I mentioned how measurements of light pollution using satellites do not account for the impact of LED lighting. LEDs are everywhere now, in our homes, offices, and streets. On the one hand, LEDs are known to last significantly longer than other types of light bulbs and cost the least. On the other hand, research has also shown that the blue wavelengths emitted by LEDs are major contributors to light pollution. Will the use of LEDs be a bane or boon for us? This post will explore the benefits of using LEDs, while the next post will talk about the harmful impacts of LED lighting.

Figure 1: Comparisons between LED and other light bulbs, Source: National Geographic

LEDs – A Boon

LEDs are highly energy efficient. From Figure 1, LEDs last for 25,000 hours, while traditional incandescent lights producing a similar power only last for 1000 hours. This means that LEDs do not need to be replaced as frequently, leading to cost savings in the long run. While traditional incandescent lights cost USD$4.80 per year, LEDs cost significantly lesser, at USD$1.00 per year! LEDs also emit a significantly cooler colour temperature, mimicking the brightness of daylight. As a result, governments have been pushing their cities to switch from traditional incandescent or fluorescent lighting to LED lighting. According to an article by LEDinside, Singapore’s Land Transport Authority (LTA) aims to convert all roads to LED street lighting by 2022, which is expected to cut the energy consumption of street lighting by 25%.

In cities all over the world, the uptake of LED lighting has also seen an upward trend, as reported by Smart City Lab. In the past 8 years, from 2012-2020, the cities of Barcelona, London, Chicago, and Copenhagen have adopted urban plans that converted a huge amount of traditional street lights to LEDs. Like Singapore, the energy and cost savings are also expected to be significant, with London estimating that it would save around $10 million each year!

It is no wonder that LEDs are getting increasingly popular with urban designers and households alike. Yet, LEDs also have their hidden costs, especially related to light pollution. What negative impacts of LEDs can you think of? Let me know in the comments below and I’ll share with you my views in the next post!

Sources:

Esther Fuldauer (2019), “Lighting the road to smart cities and sustainability”, Tomorrow.Mag, Smart City Lab, Retrieved from https://www.smartcitylab.com/blog/urban-environment/lighting-the-road-to-smart-cities-and-sustainability/

LEDInside (2017), “Singapore Aims to Convert All Roads to Smart LED Streetlighting Systems by 2022”, Retrieved from https://www.ledinside.com/news/2017/1/singapore_aims_to_convert_all_roads_to_smart_led_streetlighting_systems_by_2022

Nadia Drake (2019), “Our night are getting brighter, and earth is paying the price”, National Geographic, Retrieved from https://www.nationalgeographic.com/science/2019/04/nights-are-getting-brighter-earth-paying-the-price-light-pollution-dark-skies/

Light pollution  in the Marina Bay area, Singapore, Photo: The Independent

Hello again! In the previous post, we talked about the general trends of light pollution, and it being a global phenomenon, with 83% of the world’s population living under light-polluted skies. You might be wondering, which areas in the world are light-polluted, and to what extent are they so?

In 2016, a study by Science Advances measured light pollution on a global scale, using data from the Visible Infrared Imaging Radiometer Suite (VIIRS), an instrument from the Suomi National Polar-orbiting Partnership (NPP) satellite. It has shown that while parts of the least developed world enjoy unpolluted skies, a significant majority of the developing and developed world live under starless skies.

Figure 1: World map of artificial sky brightness, Photo: Falchi et al.

The zenith sky brightness (in μcd/m²) was computed to indicate light pollution. With the natural sky brightness (light from the milky way, stars, and airglow) at 174 μcd/m², Figure 1 illustrates the levels of light pollution measured, as a fraction above the natural sky brightness. The areas in blue represent the approximate minimum level where light pollution is considered present. As your eyes can tell,  large swathes of the developing and developed world have already reached that level – most of the United States, Mexico, parts of South America (Brazil, Chile, Venezuela, Argentina), parts of Africa (South Africa, Libya), the Middle East (Saudi Arabia, Iraq), Europe (Germany, France, Spain, Italy), parts of Russia, most of India, most of China, South Korea, Japan, and Southeast Asia. Wow, that was a really long list! But we’re not done yet.

Figure 2: Map of North America’s artificial sky brightness, Photo: Falchi et al.

Figure 3: Map of Europe’s artificial sky brightness, Photo: Falchi et al.

In the areas coded yellow and orange, the milky way cannot be seen due to light pollution. Finally, people living in the red areas will “never experience conditions resembling a true night because it is masked by an artificial twilight”. From this global map of light pollution, we can already witness the extent to which light pollution is experienced by the world at large. In Figures 2 and 3, highly developed countries, such as the United States and Europe, have already reached those levels.

The 20 least polluted countries identified in the study are poor, underdeveloped African countries (coded in grey). However, as the world continues to urbanize and develop, it may not be a surprise that these countries would also light up in the future, just as the industrialized and developing countries of China and India have.

One limitation of the study is that the VIIRS instrument does not measure the blue-wavelength of light emitted by LED lights, which significantly brightens the sky and causes harmful effects to human health and ecology (which we will explore on a separate post). Thus, what we are seeing in the skies right now may actually be brighter than what the global map of light pollution depicts. With the rising adoption of LED street lighting, our nights might just get brighter and brighter.

Coming from a little red dot in the world, never did I realize the prevalence of how others, in their own corners of the globe, are also looking up at starless skies, or skies with slowly disappearing stars. How did this study make you feel and what are your thoughts on it? Let me know in the comments below!

Source: Falchi, et al. (2016). The new world atlas of artificial night sky brightness. Science Advances 2(6).

In light-polluted city areas, significantly fewer stars can be seen in the night sky. Photo: Our Planet

Which one of these skies matches the one you see every day? For most of us city folks, we are most likely familiar with the sky on the far left of the image above, where skyglow is prevalent and only a few stars can be seen at night. If you live in Singapore, you probably might have heard of the term light pollution, and been told how you live in the most light-polluted city in the world. Most of our skies are starless at night, polluted with the bright lights of the city.

Compared with other types of pollution like water, air, or land pollution, light pollution seems to be the least talked-about topic. You are not alone if you think, “Haven’t we all grown up with those bright city lights and starless skies, and been doing just fine?” Well, those bright city lights may, at the surface, illuminate our world at night, but they ironically blind us to their harmful effects. Light pollution not only obscures the stars at night, but they also lead to a host of ecological issues and threats to human health which cannot be ignored.

The thing is, light pollution is a global issue that is set to increase in the near future with the rising trend of urbanization. Findings from The New World Atlas of Artificial Night Sky Brightness show that 80% of the world’s population live in light-polluted skies, and a third of the world population will not be able to see the Milky Way from where they live.

World map of artificial sky brightness. Photo: Falchi et al. 

It is in the hope that this blog brings to light (pun unintended) the sources and implications of light pollution, as well as what we can do about it, and more of us would ask the question, “Where did the stars go?” Follow this blog to find out more about light pollution, as I roll out more content in the weeks to come. See you soon!