International Dark Sky Week: Busting Myths
International Dark Sky Week is Apr 5-12, 2021
Light pollution is not the worst problem humanity faces. It is not the existential threat that the climate crisis presents, and it is not responsible for the increasing inequality that sees many living in crippling poverty and food insecurity. Yet light pollution tells us some important things about humanity and how we collectively view environmental concerns. For instance, if we stopped all plastics production today, we would still have a plastic pollution problem extending decades, even centuries, into the future. Light pollution is not like that: we can literally solve the problem by turning off the lights.
Of all the damages we inflict upon our environment, light pollution is by far the easiest to solve. But we do nothing but make the problem still worse, year on year.
We have known about this consequence of artificial light at night on turtle behaviour for 100 years. When a sea turtle hatches from its egg and burrows out of its sandy nest, it instinctively looks for light, even though it hatches at night. From its perspective millimetres above the sand, when it looks away from the sea, the land behind rises as a black void of danger and death. In contrast, toward the welcoming relative safety of the ocean there is a sky full of bright stars and the glow of the Milky Way. The baby turtles instinctively head to the sea because of that light. Humans come along and put our streetlights and towns along the coast, glowing many times brighter than the stars. Hatching turtles see these light sources and head to certain doom instead of to the relative safety of the sea. Artificial light at night is directly responsible for declines in sea turtle populations.
We know light pollution affects us, too. It disrupts our circadian rhythms, our internal body clocks. As anyone working night shift knows, we can fight our natural inclination to wake up with the light and go to sleep with the dark, but it takes some effort, especially when working rotating shifts. Then there’s sleep debt. We take on more activities that require light, then fill our nights with artificial light to make that possible. We live in urban environments so saturated with light that night turns into fake day. As our period of darkness shrinks, so our sleep period also shrinks. It turns out there are consequences to messing with our natural body cycles: scientists have correlated this to increased risks of various health problems, including cancer. Not that we can say these disruptions cause cancer, but it may make a person more susceptible, or it may affect the body’s defence systems, or some other mechanism may explain the increased risk.
Scientists studying circadian rhythms have discovered an interesting association between blue light and the disruption of these biorhythms. The warm golden glow of sunset, the orange of a fire and even the dim glow of old-fashioned incandescent light bulbs do not disrupt our circadian rhythms nearly as much as blue light does. Unfortunately, the super-efficient and more climate-friendly LEDs happen to be rich in blue light. LEDs intrinsically generate a blue-ish light that excites phosphors to create a broader range of emitted frequencies to emulate “white” light. As is often the case when we tackle one problem, we create a new one. We now know that photoreceptors in the eyes, even when we have closed our eyes, and even in the eyes of blind people, respond to light rich in blue light in a way that suppresses the production of melatonin, a hormone key to regulating our circadian rhythms. It seems the blue of a clear blue sky is the thing that hits the daily reset button on our bodies and sets the pulse for our biorhythms. When we use artificial light that is high with a blue light component at night, we are manually hitting the reset button on our biorhythms and knocking them all out of whack. This is not about whether we can easily fall asleep after using our phone in bed, it is about our bodies’ hormonal production being disrupted because of the effects of unnatural levels of blue light. This is now being linked to increased risks of obesity, diabetes, heart disease and cancer.
We can defend ourselves from blue light at home with light-blocking curtains and choosing how and when we illuminate the indoors. Wildlife is affected more than we are by light pollution because they cannot escape it. It has negative and even deadly effects on birds, amphibians, mammals, insects and fish. Some are as affected by blue light as we are, for similar reasons. Some are affected by colours of light other than blue, but all are affected by the intensity of light, and creatures in our urban environments and on the fringes of our cities and towns are being subjected to increasingly bright lights, because LEDs have given us the ability to quadruple the brightness of our lights for half the running cost. We are seeing a catastrophic collapse in insect populations threatening entire ecosystems and what is called ‘urbanisation’ is one of the identified factors. Light pollution is one of the things that makes our urban environments hazardous to insects.
You should not be made to feel that you are personally responsible for solving the problem of light pollution. The reality is the problem is bigger than all of us; individually, we cannot solve the problem. However, certain individuals can have disproportionately more effect on light pollution, both for the better and the worse. The choices those individuals are making are often weighted by factors that we need to address at a fundamental level. If there really is ‘one simple trick’ to solving our light addiction, it is to help spread the message that these lighting myths are busted:
Myth 1: Light Reduces Crime. There is a belief that has persisted since the electric light was commercialised that lights prevent nocturnal crime. Perhaps people confuse burglars with vampires. In fact, most crime occurs in full daylight. In fact, ‘security’ lights make it easier for crims to see what they are doing.
Myth 2: We Need Lights for Personal Safety. Streets are lit, not because it increases personal safety, but because it reduces fear. When there is less ambient light, our eyes adjust to the dark and we can make out detail, even in shadowed places. Perversely, bright urban lighting makes it easy for people to hide in the shadows because these lights deprive us of our night vision.
Myth 3: We Need Lights for Vehicular Safety. On the sporadic occasions a town is subjected to a blackout, there is no horrendous spate of vehicular accidents; every vehicle on the road is expected to have operational lights serving both as a source of illumination for the driver to see and as warning lights alerting other drivers to the presence of the vehicle. When pedestrian crossing points are lit on an otherwise dark street, the presence of an illuminated pedestrian is especially notable to a driver. Without the glare of unnecessary streetlights, actual traffic control and warning lights are more visible.
Apart from helping to dispel these myths, there are things each of us can do to minimise our personal light impact on the environment. If it is feasible for you to make these changes around your home, please consider these basic principles for outdoor lighting:
Only light areas when needed; use movement sensors and timers to limit the time lights are on.
Only light the area that needs to be lit.
Shield the light so all the light is directed down and does not spill to the sides, or worse, upwards.
Only use a light as bright as is necessary and not brighter.
Minimise blue light emissions; choose 2700K, 2400K or even 2200K lights.
I had the privilege of spending some time over the long weekend with friends and family at Totaranui in the Abel Tasman National Park, a true dark sky site. There are no streetlights. There are no illuminated billboards. The warm incandescent glow of campfires is not saturated with blue light. The toilet block lights are on sensor-timers, and about the only thing you might call light pollution came from headlamps stabbing into the dark as people made their way to them. The Milky Way glowed overhead, with the bright stars of numerous constellations burning through the darkness. Our ancestors used those constellations to navigate and to determine when they should plant their crops. Those night skies are an important part of our heritage, no matter what part of the world we live in or where our ancestors come from. They are a taonga that should be treasured and protected.