If you go outside at night and look up at the sky, the chances are that if you’re living near a city, you’re not going to see much.
That’s because cities and towns have been steadily increasing their use of specific types of artificial lights to illuminate evening activities.
By transitioning to light-emitting diode (LED) light bulbs — cities save a ton of energy, but as we are now learning, are also making light pollution worse.
LED lights are so bright they block out more stars than more traditional light sources. The animation from the Flagstaff Dark Skies Coalition below shows how our view of the sky changes dramatically when you switch from low-pressure sodium (LPS) lighting — which have the yellow glow of traditional bulbs — to the bright white light of LEDs.
LPS lighting, while still a light source that pollutes the view of the night sky, is by far the least egregious in terms of light pollution:
Cities around the world have been making the switch from energy-guzzling sodium-vapour lamp streetlights with brighter and whiter energy-saving LEDs. In fact, New York City is retrofitting all of its 250,000 street lights with LEDs in what the city is calling the biggest project of its type in the country.
But energy savings does not necessarily translate to happy city dwellers. In a piece in The New York Times, Brooklyn residents complained about the glaring white light creeping into their homes and eyes, causing many restless nights.
The eye-opening light pollution is even visible from space.
Check out how this shot of LA changed between 2010 and 2012, after Los Angeles Mayor Antonio Villaraigosa launched the Los Angeles LED Street Lighting Energy and Efficiency Program to reduce energy costs and emissions. Between 2009 and 2013, the city replaced more than 140,000 of the city’s streetlights with highly-efficient LEDs, which they say has reduced energy costs by 63% and carbon emissions by 47,583 metric tons per year.
You can see it also increased the city’s brightness substantially:
But LEDs worsen light pollution by giving off more blue and green light than the high-pressure sodium lights they normally replace. And this artificial light pollution washes out the night sky and is linked to many negative consequences.
Disrupted night and day cycles can confuse nocturnal animals and alter their hunting interactions, migratory patterns, and internal physiology.
It can also mess with our internal clocks. We produce melatonin at night to help us sleep, which is regulated by light and dark cycles. If we’re exposed to light at night, this can suppress melatonin levels, leading to sleep disorders or other problems such as headaches, anxiety, and obesity.
Groups like the Flagstaff Dark Skies Coalition and researchers with Cities at Night, a project that is compiling images of cities from space to make a Google-Maps-style map of images of Earth at night, are bringing awareness to the glaring issue of light pollution. If you want to support their research, check out the Cities at Night KickStarter project here.
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