Less Skyglow, More Starshine
Reducing Light Pollution
I much prefer the endless days of early summer to the dark depths of winter. The Danish concept of hygge is all well and good, but it goes only so far, come January, in alleviating my sunshine deprivation. Pretty sure I’m not alone in this bias.
So it gives me no joy to confirm we’re at that time when the nights are falling earlier and lasting longer. If you're like me, there's a huge temptation to ward off the gloom by turning on the lights. All of them. I just wanna flip the switches and grit my teeth ‘til the next equinox rolls around.
Not gonna do it, though, and I hope you’ll join me in resisting the pull.
What Is Light Pollution?
Light pollution – the inappropriate or excessive use of artificial light – is a major factor in biodiversity declines around the world. For billions of years, living things have relied on predictable patterns of light and dark for their survival. For one thing, nighttime darkness is a habitat for nocturnal species. When we light up our houses and yards like Christmas trees, we’re making those spaces unlivable for many creatures. We’re also messing with complex ecosystems based on carefully timed circadian rhythms that govern sleep, reproduction, migration, hunting, hibernation, protection from predators, plant budding and flowering, and leaf drop. Our insistence on lighting up the night is having a lethal impact on amphibians, birds, mammals, insects and plants.
To give you some sense of the scale, a 2016 study found that 80 percent of the world’s (human) population lives under light polluted skies. In the U.S. and Europe, 99 percent of us experience “skyglow,” which is the brightening of the night sky over inhabited areas. The term may sound romantic, but it’s deadly. You know you’ve got skyglow if you can’t see the Milky Way on a clear night. Apparently, when an earthquake knocked out power to LA in 1994, people called 911 to report a “giant, silvery cloud” in the dark night sky. They’d never seen the Milky Way before, so its sudden appearance seemed alarming.
Why Should We Care?
Sea turtles hatch at night on beaches. They find their way to the sea by detecting the bright horizon over the ocean. Artificial lights draw them away from the sea and usually to their demise. Millions of hatchlings die this way every year in Florida alone.
Migratory birds depend on seasonal cues to time their flights. Artificial lights can cause them to begin their voyages too early or too late and miss critical climate windows for nesting, foraging and other life-sustaining behaviors. Also, birds that migrate or hunt at night navigate by the light of the moon and stars. Urban lighting can cause them to wander off course. Once inside the cities, some will circle buildings endlessly until they die of exhaustion. Every year an estimated one billion birds die from colliding with buildings and towers that are lit up, for no good reason, like opera house chandeliers.
Fireflies flash to signal for mates, warn predators, claim territory, and send other messages to their kinfolk. The survival of many firefly species depends on them detecting one another’s flashes in the dark and driving away predators. Artificial lights make their signals invisible to friends and foes alike.
Mayflies, which live and breed for only a day, can be confused by light bouncing off asphalt and lay their eggs in the street instead of a lake or stream. A mistake like that can wipe out an entire population overnight.
Moths are famously drawn to outdoor lights. It’s estimated that a third of the flying insects swirling around those lamps die by morning, either from getting eaten by predators or from exhaustion. Moths are of course critical pollinators. They also produce the caterpillars that are essential foods for chicks.
Amphibian, bird and insect populations are declining precipitously; these are just a few examples. Light pollution is one of the causes.
Even if you don’t care much about sea turtles or fireflies, remember that they’re part of a web that performs ecosystem functions that keep us humans comfortable, healthy and…well, alive. It’s thus very much in our interest to keep them alive.
How Can We Make a Difference?
Turn off any unnecessary outdoor lights, particularly between 11pm and 6am. (We’ve turned off the ones around our yard that were mostly decorative. We can always turn them on again when we need them.)
If you have outdoor lights that are absolutely necessary:
switch from bluish- to yellowish-colored bulbs (we’ve put yellow bulbs in the sconces by our front door);
install motion-sensors (we’ve put motion-activated bulbs at our back patio); and/or
keep lights low to the ground, directed downward and shielded.
Draw curtains and shades to keep inside light from flooding out.
If you have influence over the management of any office buildings, urge them to turn off their lights at night.
These are simple things we can all do – no digging or pruning is even required! Let’s not think of it as losing wattage. Let’s think of it as adding starshine to our lives.
Have you seen La La Land? I love that movie for its score, choreography and star-crossed plot. Also, as Walter, the wise elder statesman of our neighborhood, so accurately observed, the leads aren't hard to look at.
Resources
Jason Daley, “The Devastating Role of Light Pollution in the ‘Insect Apocalypse,’” Smithsonian Magazine, November 25, 2019.
Fabio Falchi, et al, “The New World Atlas of Artificial Night Sky Brightness,” Science, June 10, 2016.
Elizabeth Pennisi, “Fatal Attraction to Light at Night Pummels Insects,” Science, May 7, 2021.
“80% of World Population Lives Under Skyglow, New Study Finds,” International Dark-Sky Association, June 10, 2016.
“About Light Pollution,” Firefly.org.
“Lights Out,” Portland Audubon.
“Lights Out Salt Lake,” Tracy Aviary Conservation Science Program.
“Lights Out Texas,” Birdcast.
“Light Pollution,” International Dark-Sky Association.
Mention sensors here!
Oh and what a difference to be in a part of the world w little light pollution - the stars and the wildlife make us want to be outdoors.
Good job relating a very important topic. Thanks!