There are some places in the world where people still do live under pristine skies.
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The researchers used satellite and sky brightness data to create a global atlas of light pollution, the artificial illumination of the night sky sufficient to substantially wash out starlight.
The night sky looking south at Buffalo Peaks Wilderness Area north of Buena Vista, Colorado. One-third of humanity can no longer see the Milky Way.
The proliferation of light pollution started in the 1950s and 60s and has continued to expand every year, said Chris Elvidge, a scientist with the U.S. National Oceanic and Atmospheric Administration and a co-author of the study. “I feel some enhanced connection to the cosmos”. The global dark sky atlas, produced by an worldwide team of researchers, suggests there’s only one spot in Washington state that’s untouched by the effect of artificial light.
She says light pollution is still kind of on the fringes of what most people consider to be pollution, and one of the biggest challenges her organization faces is increasing awareness of this problem in developing countries.
Other parts of the world fare better, however.
Light pollution over Joshua Tree National Park.
“Some of the worst light pollution is close to gas flares in Nigeria and Russian Federation, where there is no shielding”, said Elvidge, explaining how the lack of a protective barrier allowed light to go straight up into sky. It is one of humankind’s most omnipresent forms of environmental adjustment, exemplified by the nocturnal glow over cities.
The researchers calculated several degrees of light pollution, starting from the level at which artificial light obscures astronomical observations up to the level at which the midnight sky is as bright as it is at twilight. In addition, a whopping 83% of the world’s population lives under light-polluted skies.
“It’s basically the light that’s escaping earth and heading out to space”, he said. It’s been taken up by cities and towns. “This is where the model is powerful for predicting light pollution threats from distant cities now and in the future”.
Industries and individuals alike can also do their part to minimize light pollution by adopting simple solutions, such as switching to shielded fixtures that direct light downward instead of into the surroundings, and using amber, or warm colored bulbs, instead of cool blue LEDs, which amplify sky brightness two to three times above the typical output, the report says. “But if the light pollution is getting in the way, then you are taking away a very nice source of awe for people”. “Losing a clear night sky will harm our capacity for wonder and put a dent in our spirit of common cause”. Evidence also suggests that artificial light at night can upend the circadian rhythms that humans depend on, increasing the risk of health problems such as depression, diabetes, sleep disorders, obesity and breast cancer.
But for those of us who have never left the city to spend a night staring at the sky, it’s hard to register just what we’re missing-the night sure seems dark, even in an urban metropolis.
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“Predators use light to hunt, and prey species use darkness as cover”, says Christopher Kyba in an article for the International Dark Sky Association.
