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Health & Fitness

Light Pollution, the Environment, and You

A blog about the impacts of light pollution on the environment and what you can do to help.

Throughout this blog series, I will be discussing the various means that light pollution impacts your world and, perhaps more importantly, how you can make simple changes that will minimize the negative aspects while maintaining the benefits associated with the light.

What is Light Pollution?

Light pollution is defined by the International Dark Sky Association (IDA) as the “excessive and inappropriate [use of] artificial light.” Light pollution is a growing problem that is negatively impacting wildlife (of which we are the stewards), needlessly increasing our energy consumption, impairing our health, distancing us from our heritage and, paradoxically, decreasing our security.

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Light pollution is remarkably easy to spot. Walk outside at night and take a look around and find a light. Any light. A simple rule of thumb is that if you can see the source of the light, and you are outside of the target area for that light, you are looking at an improperly shielded light fixture and a point source of light pollution. The concepts of “source” and “target area” are specific, important, and will be addressed in an upcoming blog entry.

How Does Light Pollution Affect Living Things?

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The natural 24-hour rhythm of living things is tuned to the day-night cycle that has been seen on Earth since before life began. This is an inherited trait present in species from bacteria, to plants, to insects, to humans, and manifests itself in the form of Circadian Rhythms. The presence of this clock is most clear to our species when it is out of sync with our surrounding environment, such as is felt during periods of jet lag. This clock is reset and the rhythms entrained by the cycle of darkness to light.

While jet lag can be annoying for us, the disruption of circadian rhythms in other species can lead to changes in behaviors that can be fatal. For instance many songbirds (Blue Tits, Great Tits, Blackbirds, Robins, etc) use the timing of their mating calls as an indicator of putative mate fitness. Light pollution has been demonstrated, in at least 80 percent of the species examined, to alter the timing of these songs, which alters the male fitness selection by females. In layman’s terms this means that offspring from songbirds near sources of light pollution are genetically less fit, and more likely to die, than birds that live in places away from the light pollution.

Species like amphibians, spiders, and insects, all show measurable changes in behavior upon the incidence of light pollution. Walk near a riparian area during the night and listen to the bleatings of the frogs or the chirping of the certain insects. These are mating and territorial calls. Now shine a flashlight on the area. All that remains is the rustling of the trees in the breeze. The silence will remain for quite some time after your light is gone. Time gone from the mating rituals of the impacted species. Time away from foraging. Time lost for survival.

There are literally hundreds of primary research articles available in the scientific literature that document the impacts of light pollution on species in the environment. Nearly all that I have come across have demonstrated a profound and negative impact upon the species examined. There are, however, examples of species in nature that do not appear negatively affected by light pollution. These are coincidentally species that have adapted well to humans, such as raccoons, opossums, rats, and crows.

These newer species can, however, negatively impact native species an example of which is the American Crow. This bird is attracted to areas with pole lighting, likely to avoid predation by owls, and roosts higher than would normally without the light. The crow is a nest predator of native songbirds and reduces those birds ability to survive. Nature is very complex and pulling on one string, making a change here or there, can have large impacts in areas that may not seem obvious at first glance. But with study and thought, they become more clear.

My next entry will focus more on what can be done to minimize the impact of light pollution on the environment. Although the impacts of light pollution are indeed profound, the solutions are fortunately simple and inexpensive.

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