Deep Dive
Blinded by the light pollution: the artificial answer to nature’s sudden confusion
You’re about to go on holiday. Somewhere hot, somewhere unfamiliar. In preparation, you plan your journey. But hang on, someone is repeatedly shining a light in your eyes. Over and over, you forget where you’re going every time you look at a map.
In many ways, this is a reality for some species as nighttime light pollution (NLP) spreads and intensifies. It’s there to help us navigate, grind, and generally exist, but at what cost?
First, light pollution…
Between us, it’s the excessive or inappropriate use of artificial light with harmful effects on humans, wildlife, and even an unsuspecting starry sky.
Seeing stars, at least for now – light pollution in the night sky
What’s that, up there? The universal feeling of darkness sweeping us into a deep sleep after a long day is giving way… to a world of artificial light that exists only at night. No surprise that as society grows, we need more streetlights, lamps, and LED lights – the light pollution brigade.
One study found that between 2011 and 2022, the sky was roughly 9.6% brighter each year, and it’s affecting our relationship with the stars. Apparently, a child born today who could see 250 stars at night will only see 100 by their 18th birthday.
Nature’s nightwalkers are struggling with light pollution
70% of mammals are nocturnal, which makes diurnal humans – active during both day and night – the odd ones out. Nature started the other way for many reasons: swerving predators, finding nocturnal prey, and even a cooling break from boiling hot days. Artificial light might help us, but it’s throwing the nightwalkers off their natural flow; in some cases, this can be fatal.
Species in the spotlight
Snowy Plover
Having the light on when you’re trying to sleep is rarely life or death. Unless you’re a snowy plover. They nest and rest in open areas on sandy beaches, preferring dark spots to hide from predators overnight. As light pollution grows, they’re increasingly lit up, like tiny little Christmas trees or glowing lunches. Unsurprisingly, they’re avoiding these spots, meaning their habitat range is growing smaller and their sleep deprivation deeper.
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Monarch butterflies
NLP is to Monarch butterflies what traffic jams are to humans – certified journey busters. These fluttery navigators love a migration – sometimes stretching from Canada to Mexico – but artificial light is messing things up. It throws their timing, meaning they can take off too early or land too late, but also keeps them from processing proteins at night, which is key to forming their famous internal compass.
Birds
Specifically, insect-eating, woodland-dwelling migration experts like the near-threatened and rapidly declining wood thrush. At night (birdie rush hour), glass buildings reflect artificial light that spins our feathered friends into a frenzy, leading them off their migratory path and even to their deaths. As many as a billion birds die every year in a deadly hall of mirrors, and in October 2023 alone, over 1,000 birds fatally collided with the McCormick Place building in Chicago!
Like you’d flex your moves on a date, fireflies use dazzling light displays to do the same. (170 firefly species = a lot of different sauce.) But as you can imagine, artificial light is killing their vibe. In bright light, females go dark and stop illuminating totally, and with the lack of a response, the male fireflies eventually give up. Plus, if a firefly’s home suddenly becomes well-lit at night, they pack their bags and go. Bye-bye, firefly. Just like that. Tough times, considering their habitat range is severely fragmented.
How does light pollution affect humans and pets?
Much like noise pollution, artificial light doesn’t just affect the species we share this earth with, but also the people. It’s linked to all sorts of nasties, like depression, obesity, diabetes, heart disease, Alzheimer's, and even cancer.
One definite casualty is our circadian rhythm, our internal body clock. Just like when you go on holiday, switching between time zones, artificial light also inhibits melatonin production, the hormone our bodies rely on to signal when it’s dark and, therefore, sleepy time. Without our normal melatonin stocks – decreasing as light pollution spreads – our bodies can struggle to get decent shut-eye.
In less human, do you have a dog? Chances are they’ll be growling about artificial light, too, especially given their sensitive little peepers. Canines are highly adapted to function in low light; their eyes are three times as sensitive to the flicker of LED lights that are mostly invisible to humans, causing mayhem for our beloved companions.
What can we do about light pollution?
As cities and towns grow, the obvious idea of ‘using less artificial light’ is much easier said than done. But that’s not to say we’re powerless against human illuminations. Here are a few tips from us that you may or may not already be doing:
Turn off unnecessary indoor lighting - i.e. office lights after you have left.
Minimise the use of blue light – especially for outside lights. It has a greater dispersion than other lights and contributes more to sky glow.
Keep the blinds closed when using indoor lights at night.
Be aware of artificial light usage, especially if you’re close to sensitive areas, like beaches, where turtles use to lay eggs.
Spread awareness of the harmful effects of light pollution to your friends, family, and colleagues.
Individual change is a start, but we need the policy and legislation bigwigs to get on board, too. Excitingly, The All-party Parliamentary Group for Dark Skies (APPG) has suggested big changes in national legislation – their plan consists of 10 major and exciting ideas, which you can see here.
These steps, plus our individual efforts, could reduce the negative impacts of artificial brightness, especially in cities. There’s light at the end of the tunnel – a natural glow full of promise.
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