Light pollution on the rise, 80 per cent affected

Wednesday, June 15, 2016, 9:34 AM - Researchers have come out with some new numbers on just how few of us are actually able to see the night sky.

According to a study published in Science Advances this week, more than 80 per cent of humans, including around 99 per cent of people in the U.S. and Europe, experience some form of light pollution at night.

For a third of humanity, it's so bad the Milky Way can't be seen with the naked eye, rising to 60 per cent of Europeans and 80 per cent of North Americans.

"About 14 per cent of the world's population don't even use their night-time vision," one of the paper's authors, Dr. Christopher Kyba, from the German Research Centre for Geosciences, told the BBC. "The night is so bright that they use their colour daytime vision to look up at the sky."

Image: Science Advances

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Topping the list of most light-polluted nations is the city-state of Singapore, whose residents all live "under skies so bright that the eye cannot fully dark-adapt to night vision." Other big night-sky losers are the highly urbanized Gulf states of Kuwait (98 per cent), Qatar (97 per cent), United Arab Emirates (93 per cent) and Saudi Arabia (83 per cent).

On the flipside of the story, populations in the African nations of Chad, Madagascar and the Central African Republic have the clearest night skies. Unsurprisingly, Greenland, a Danish territory with substantial home rule, has the smallest percentage of its area without "pristine" skies, at 0.12 per cent.

Canada's skies are nowhere that pristine, but we compare favourably to other G20 countries in terms of percentage of territory with clear skies, at almost 90 per cent of non-polluted night sky, second only to Australia.

However, our country ranks higher on the list of light pollution by population, in fourth place behind Saudi Arabia, South Korea and Argentina, likely because most of Canada's population lives in urbanized areas.

Image: Science Advances

The researchers came up with this "atlas of artificial sky luminance" by using high-resolution satellite data and ground-based measurements. It seems they attempted to account for snow cover in their calculations as well, using Canada as an example.

"The use of November and December 2014 data means that radiance is somewhat increased in towns that had considerable snow cover at that time (for example, Edmonton and Calgary in Canada, but not Vancouver or Toronto, nor most northern cities in the United States)," the researchers write. However, they also say they tried to account for the effects of weather, and noted that snow cover may be less of a factor in cities, where it usually promptly removed from road surfaces.

The researchers say brighter night skies aren't just an aesthetic issue. It affects nocturnal animals' wellbeing, and can have an impact on disease and sleep disorders, according to the BBC.

Kyba told the BBC said the technology we use to light our cities at night needs to be improved.

Image: Tracy Kerestesh, Melville, Sask.

"There's a big difference between having a well-lit street, which means everybody can get around really easily and safely, and a brightly lit street, which could mean there's too much light and it's not helping anyone," Kyba told the BBC.

The research comes at a time when many jurisdictions are switching, or planning to switch, to more energy-efficent LED lightning, but Fabio Falchi, the lead author of the study, told Astronomy Now that the transition needed to be done right.

"Unless careful consideration is given to LED colour and lighting levels, this transition could unfortunately lead to a 2-3 fold increase in skyglow on clear nights," Falchi told the magazine.

SOURCE: Science Advances | ARCGIS | BBC | Astronomy Now