The Ecological & Human Need for Dark Skies
By Jason Kahn
“Saving the Dark” is a documentary about light pollution created in association with the International Dark-Sky Association.
Like many forms of pollution, light pollution is not a matter of what it is, but how much of it pervades the planet. It is a form of pollution that has quietly made its impact known first to entomologists and wildlife ecologists in the 1970’s and more recently to crime statistic specialists at the FBI and sleep specialists at several universities worldwide. The relatively recent rise in concern of this pollution coincides with the rise in the use of light-emitting diode (LED) lights and halogen/vapor lights that too often mimic daylight at night. The spread of light pollution, here in the US, has increased several hundred times since the ’70s. And is estimated to increase several hundred more times in the coming decades.
The spread of light pollution has been spurred on by an overdeveloped sense of increased security in a seemingly dangerous world. Humans feel more secure in well-lit areas at night. Perhaps this is a holdover from our Homo erectus forebears who used fire to keep wild animals out of camp. Now we recreate daylight at night in an attempt to protect ourselves from the fellow humans that we perceive intend to do us harm. New research from decades of FBI crime statistics however shows a far more likely chance of a crime being committed in precisely these well-lit areas. Nowhere in our quest for safety did we intend to harm our wild neighbors, that was purely coincidental. Unlike many forms of pollution, light pollution’s harm is easily undone with very little effort and cost on our part.
The International Dark-Sky Association was formed in 2001 by a collective of scientists, mostly astronomers, as a means of preserving the night sky for land-based astronomy. Places like Mount Wilson in Los Angeles County were finding it difficult to observe dim objects in the sky due to the high degree of light pollution emanating from the city of Los Angeles. The Milky Way itself was becoming a foreign object in the sky for decades by 2001. Since its beginnings in 1904, Mount Wilson Observatory enjoyed relatively great star watching until after WWII when Americans began moving to Southern California to enjoy the plentiful jobs and pleasant climate. With cities comes lighting, as population grew so did the light pollution. Now if there is a power failure in Los Angeles people look up at the night sky and call 911 when they see the Milky Way Galaxy. Surely, they think, this can’t be natural. There must be something happening to the sky.
As talk amongst scientists increased with the advent of the world wide web, the biologists who studied animal migration began to chime in as well. Animals that navigated by the stars were being drawn off course by artificial light. Back in my undergrad days a biologist at SUNY Geneseo, Dr. Roberts Beason, using the university’s planetarium, tested several species of birds’ navigational instincts, changing the orientation of the stars projected on the dome of the planetarium to determine how the birds responded to the change. The findings instructed the researchers that birds do navigate using the night sky just as we humans did initially several hundred thousand years ago.
Insects, like lightning bugs that require darkness to reproduce, were showing precipitous drops to their populations. The reason it seems was light pollution kept them from finding each other in the too-bright night world. The Loggerhead and Leatherback species of sea turtles use not the stars, but use light and dark as a means of returning to the sea upon hatching on beaches. Before beachfront communities were a thing, turtles would hatch on the beach at night, to escape the predators who patrolled the beaches during the day, and they were drawn to the light color of the surf breaking on the shore. The inland was darker then and the faint light off the surf was all the stimulus needed to draw them to the safety of the ocean. Now beachfront homes are plentiful and overly lighted to allow the homeowner to see the ocean at night. As a result, too many of the hatchling turtles are drawn away from the ocean by the artificial light of people’s homes.
Our trees have also suffered from this infusion of artificial light. Like houseplants that are induced into year-round growth and extended blooming periods so to have our neighborhood trees and plants. It has long been known that the yearly cycle of sprouting leaves and shedding leaves is triggered not by changing temperatures but by the seasonal changes in light. Depending on the latitude a threshold of daylight hours informs the tree chemically that it is safe to produce buds, that the chance of a late cold snap is sufficiently low, and the benefits of taking advantage of the lengthening daylight should not be ignored. Research has proven that trees subjected to 24 hours of light in parks, city streets, malls, and campuses have a decreased life expectancy due in part to the trees’ inability to safely estimate when it’s proper time to produce buds and when to drop their leaves.
The number of species affected by the growing light pollution problem is large and expanding. Oddly enough and justly we humans have in recent years been added to that list. As a species that evolved with dark skies, we slept shortly after the sun set and we woke when the sun rose. Our circadian rhythms developed around that cycle and unknowingly the body’s chemistry developed melatonin as a sleep-inducing hormone. Produced by our pineal glands at night it allowed us to sleep when daily survival required us to be alert and rested. With the advent of population centers, nighttime lighting increased exponentially, and today or more accurately tonight, we try to darken our rooms to assure a good night’s sleep. Too many of us, however, can’t achieve that needed sleep due to light intrusion around or through the barriers we construct. The result has been a generation of people who live in communities with street lights, neon lights, porch lights, night lights, and far too much light given off by our media devices we keep close by at night. A sidebar here. A friend of mine has a dog who is terrified of lightning. So much so that at night the dog would whimper at the flashing of his mobile phone as it recharged at night. It took him a few weeks to figure out the problem. The point being it was a minuscule amount of light that disrupted the sleep of both his dog and himself. It was an easy problem to solve. Luckily enough so is the overall light pollution problem.
Misconceptions about exterior nighttime light and safety abound. A 2015 study published in the Journal of Epidemiology and Community Health found that streetlights and outdoor lighting in general don’t deter crime, prevent accidents, or by extension make us any safer. From college campuses to shopping malls, the study shows that improper lighting creates harsh shadows and also produces areas overly lit that we humans perceive as being safer. In these improperly lit areas, the human eye cannot penetrate the harsh shadows adjacent to the overly lit area. So a person intending us harm can quickly emerge from the shadows. It turns out wattage is part of the problem. The other part is the directionality of the light. Light shining upward is wasted and disruptive to many species, including humans. Too bright a light creates a too dark shadow. Softer lighting, specifically non-blue LED or compact fluorescent lights (CFL) in a warmer color such as yellow or orange with a shield directing the light towards the ground is both safer and more cost-effective. On a global scale, cities have spent billions of dollars lighting up the night sky needlessly. Generating the power to these lights has contributed millions of tons of CO2 to the atmosphere annually, thus contributing to global climate change, with no human benefit.
Luckily these forms of softer warmer lights are also more faunal, and floral friendly than their bluer, daytime colored lights. It seems that animals, plants, and insects display minimal disruption in their behavior when these lights are used outside exclusively. It should be added that our outdoor lights should be turned off entirely when not needed. So what are we left with at this point? By reducing the amount and changing the color and shading of outdoor nighttime lighting we can sleep better at night and feel better during our waking hours. Our nearby plants and trees will continue to provide us with the ecosystem services such as removing CO2 from the air, replacing that gas with much-appreciated oxygen as well as providing habitat to our beloved birds and wildlife. Our atmosphere will move a bit towards stability and sustainability. Our streets and parks will be safer, our neighbors in the house next door will have less to complain about us, and we will have the added benefit of once again being able to enjoy the utter beauty of the dark night sky.
Back to Mount Wilson for a moment. Land-based astronomers do comparatively little harm to the world by number and activity. They also provide us with the vigilant service of watching the sky. Amongst their duties is to find and establish the path of near-Earth objects. Comets, asteroids, and the increasing amount of space junk we have placed in Earth’s orbit are all potential threats to life on Earth. The larger and therefore more dangerous objects are collectively known as “planet killers.” These objects are so dim when viewed at distances where we have a window of opportunity to act, reflect, make amends or kiss flossing goodbye that even small amounts of light pollution mask their presence longer than we may desire. Speaking strictly for myself I would embrace the time afforded me by earlier detection. I have never seen a comet I didn’t like.
Jason Kahn recently joined The Rewilding Institute board of directors after retiring from serving as a bike mechanic after retiring from serving as an Earth Sciences teacher. Jason continues to cycle regularly and is plotting a bicycle-supported wildways trek next year with his rewilding friends.