Losing the Night
Are new municipal lighting technologies and practices stealing our night sky?
Human connection to the night-day cycle is part of our very being; night is a time of quiet, rest and renewal.
Circadian rhythms—set by light and dark—help regulate our blood pressure, sleep, mood and digestion. Plus, there is the emotional connection to the night sky—stargazing during camping trips, for example, and serene nighttime walks.
However, nighttime is changing. Municipalities around the world have been switching their streetlights from the muted sodium lighting of old to LED: light-emitting diodes. Energy efficient, affordable and long-lasting, there are several reasons to make the switch. But this new application has revealed unintended consequences.
With street and outdoor lighting more efficient and powerful than ever before, municipalities around the world may be succumbing to the temptation to over-light, as LEDs are often effectively far brighter and are being installed in more places.
The International Dark-Sky Association (IDA), based in Tucson, Arizona, is the world’s leading body dedicated to fighting light pollution and preserving the night sky. They also offer resources to help planners and municipalities preserve dark skies. Among their key principles: light only as bright as necessary; light only where necessary.
According to the IDA, between 2012 and 2016, the amount of the Earth’s nighttime surface lit artificially increased by two per cent annually. In some areas, however, annual increases were almost 10 per cent.
But what can be done? In one IDA-led study in Tucson, street lighting was dimmed by 60 per cent. The resulting reduction in light emissions was measurable by satellite photography. Even after this reduction, there was no perception that lighting was inadequate and no identifiable decrease in safety.
“Among the causes of light pollution is the popular belief that the use of outdoor light at night necessarily improves road and traffic safety and discourages or prevents the perpetration of both violent and property crimes,” says John Barentine, International Dark Sky Places Program Manager (Acting). “While under certain circumstances the careful application of outdoor lighting may improve nighttime safety, this belief generally is not grounded in peer-reviewed scientific evidence.”
Most outdoor lighting is planned at the municipal level. According to the IDA, this is good news for those wishing to help preserve or improve dark skies in their area. Residents can express to their town and city councils that dark skies are important to them and can influence decisions that help preserve their local night sky.
Ultimately, why should we want dark skies to be part of our daily life and part of our future? Barentine explains: “The night sky is an important part of our collective heritage as humans on this planet, and it connects us to nature in ways otherwise being lost. But it’s more than a matter of whether we can see the night sky. If we make dark skies a part of our future, we attend to concerns ranging from climate change to wildlife conservation to public safety. And I think a healthier, cleaner, safer world is something we can all support.”
This article originally appeared in the Summer 2021 print issue.
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