|United States at night. Image from NASA Earth Observatory|
Growing up, I lived high on a hill above the Snoqualmie Valley, where most nights the lights from the prison in Monroe suffused the night sky with the orange glow of perpetual sunset. The glow was particularly noticeable on overcast nights, when the cloud ceiling dispersed the orange light over even greater distances. At the time, I had no idea that what I was seeing was, in fact, pollution. Light pollution.
While light seems an innocuous thing (and in the case of the prison, a necessary thing), when it occurs at the wrong time of day or year, in too great a quantity, in the wrong color, or without direction, light can be a harmful thing for the environment, for wildlife, and even for humans.
Impacts on the environment
Light pollutes the night sky, and energy used to produce the light can pollute the air and atmosphere with carbon emissions, since much of the world uses fossil fuels to produce this energy. Our climate is changing and earth is warming due to humanity's carbon dioxide emissions, and to think that a portion of those emissions are coming from unnecessary light pollution is dismaying.
Impacts on wildlife
Birds, fish, reptiles, mammals, amphibians and insects are all adversely affected by light pollution. Many of the basic life functions of these species such as feeding, reproduction, and migration are governed by light and dark, by the waxing and waning of daylight hours as the season change. Artificial light can disrupt and confuse these basic life functions, leading to the demise of individuals and causing entire species to be threatened. As our communities creep further into previously undeveloped areas, greater numbers of wildlife are subjected to the impact of our presence.
A 2016 State of Our Watersheds report prepared by the Muckleshoot Indian Tribe states that salmon may be adversely affected by light pollution. On their long journey from the ocean back to their natal streams, salmon travel up rivers running through urban areas that are well-lit at night. Salmon are attracted to artificial light, and may be led off course or into the waiting mouths of predatory fish and birds that hunt by sight and who take advantage of the extra nighttime lighting.
Migratory bird species are also harmed by light pollution. Birds often migrate at night, and can become confused or thrown off-course by bright, artificially-lit cities. Many of these birds are killed after flying into the windows of high-rise buildings left lit up at night. The Audubon Society has started a Lights Out campaign as part of their Bird-Friendly Communities program, aiming to protect birds by encouraging building owners to turn out their lights when bird migrations are occurring.
Impacts on humans
Light pollution adversely affects humans as well. Our very health can be impacted by artificial light: both the light from our screens and devices, and the hazy nighttime glow illuminating the cities and neighborhoods that comprise our habitat. Just like wildlife, our bodies run on circadian rhythms that respond to the changing light of day and night. When we artificially extend the daytime with light, our bodies can lose touch with those circadian rhythms which causes difficulty sleeping and a host of other health problems. In addition to these health impacts, I think we can all attest to the annoyance caused by a too-bright streetlight shining right into our window when we're trying to sleep at night!
Here's another way light pollution can negatively impact us: it prevents us from seeing the night sky. While illumination of the night sky and blotting out of the stars is the most obvious impact of light pollution, it's probably the one on which we spend the least amount of time pondering how it harms us directly. Where would we be, as a society and as individuals, had we never had the opportunity to stand before a dark night sky and stare in wonder at the stars overhead? There is value in the wonder and the perspective provided by a starry sky, where we are faced with the cosmos from which our very planet was created. National Geographic - among other outlets - reported a few months ago that 80% of Americans can no longer see the Milky Way, the cloudy band of stars and dust, the center of our galaxy, that arcs across the sky. There's something intangible but immensely important lost when we draw a veil of light between ourselves and the stars.
What can we do?
When darkness falls, our cities, neighborhoods and streets are set ablaze with light. While necessary for safety and so that we humans with poor nocturnal vision can see where we're going, this light is often excessive, wasteful, and poorly thought out. With a few thoughtful choices, we can minimize the impact of light pollution in our communities:
- Ensure that all outdoor lights are shielded. This means there is a hood or shield on the fixture that directs light in the proper downward direction, rather than casting light upward toward the sky. We can change the exterior lights on our homes, and can urge our cities, power companies, and other responsible jurisdictions to retrofit or replace streetlights that need shields.
- Only use light bulbs that give off warm light. Longer-wavelength red, orange, and yellow light is less perceptible and less disruptive to wildlife than the glaring blue light often given off by LED and fluorescent bulbs. If you have those blue-spectrum bulbs, it's time to replace them! Pay close attention to the packaging when you shop - you should be able to find these same energy-efficient bulbs in warmer colors.
- Turn off all unnecessary lights. This includes indoor lights that may shine out through windows, and exterior lights that just aren't needed. I have a light that floods my backyard, but only turn it on during those rare occasions when I'm outside after dark, taking out the garbage. All of my neighbors keep these lights off as well, which actually creates a pleasant dark space in the shared sky of our closely situated backyards. Not only will you help minimize light pollution, you'll also decrease your energy usage.
- Get involved. Find a local chapter of the International Dark Sky Association, the Audubon Society, or other group involved on the issue, and make a donation or volunteer your time to support their light pollution programs. Contact your local jurisdiction about light pollution ordinances, and encourage their adoption if there aren't any already in place. See unshielded streetlights or notice a park ablaze with light well after hours? Contact the responsible jurisdiction and let your voice be heard!
Seeking to escape the yellow glow that represents the Puget Sound region on the map above? The Washington Trails Association has compiled a list of dark places in our state, where starry skies and the Milky Way can still be seen.
For more information, watch this short video from the International Dark Sky Association called Losing the Dark: