Light Pollution: Is It Unstoppable?

This image of a portion of the continental United States at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The satellite detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight. Minneapolis is at upper right with Chicago (and the dark thumb of Lake Michigan) above center. NASA Earth Observatory/NOAA NGDC

I’m no fan of bad news, but it can have a positive effect in calling us to action. The news is not good for light pollution. A new study by Christopher Kyba (German Research Center for Geosciences) and his international team using night satellite photography reveals that from 2012 to 2016, Earth’s artificially lit outdoor area grew by 9.1% or 2.2% per year Continuously lit areas, where lights are on from dusk till dawn also grew by 2.2% per year.

It isn’t hard to guess why lighting is becoming more pervasive. The cost is dropping. LED lighting, which is quickly replacing the more traditional sodium vapor (orange-colored) and incandescent lighting used to light streets, businesses and homes, costs around half as much. You’d think we’d be smart enough to make wise lighting choices and pocket the savings, but that’s almost never the case. Whenever a new, cheaper technology comes along, we use more of it and negate the energy savings. Just human nature.

This photo was taken around 4 a.m. last month from the eastern edge of the city of Duluth, Minn. Poorly-shielded lighting throws up a curtain of glare in the western and southern half of the sky. The constellation Orion is visible at center. Bob King

More lights are going up and they’re far brighter than the older technologies despite the fact that LEDs are built to be continuously dimmed to fit the needs of the roadway or homeowners who might find the blue-white glare intrusive. As a result, according to the study, “the world has experienced widespread “loss of the night,” with half of Europe and a quarter of North America experiencing substantially modified light-dark cycles.”

There is something of a temporary silver lining in that countries such as Italy, Netherlands, Spain and the U.S., lighting growth has been stable. (Not so in my town, however). Also on the plus side, most LED streetlights and parking lot lights are contained in reasonably well-shielded housings with the light aimed directly downward and not out to the sides or up … except in some ornamental lighting, which is often poorly shielded and a key sources of glare on streets and homes. Most new growth in lighting occurred throughout South America, Africa and Asia.  Sadly, this is one area in which no one needs to play catch-up.

This is an example of a poorly-shielded, ornamental LED light fixture. It may look pleasing, but much of the light is wasted on the sky and as glare in drivers’ eyes. Bob King

Looking more closely, they found that light levels in the centers of major cities had dropped somewhat due to LED use with their generally better shielding. However, that was offset by an increase of lighting in outlying areas and suburbs. The researchers also recorded skyglow spillover from urban areas due to LEDs. Air scatters and spreads the blue-white light common to most current LEDs much more efficiently than warmer colors, further brightening the out-of-town skies.

The team concludes that while savings have been realized in transitioning to LEDs, on the global and often national scale, these local decreases are outweighed by increases from additional lighting. And the reason additional lighting is on the rise is due to the lower cost of LEDs. We’re in a vicious circle.

World maps showing the rates of change of the lit area of the world (left) and the measured brightness of each country (right) during 2012–2016. The warmer the color, the higher the rate of change. Artificial lighting is rapidly increasing across much of Asia, Africa and parts of South America. Christopher Kyba et al. / Science Advances

You and I care about good lighting. We know that glare impairs driving and over-lighting means wasted cash and energy, but it goes deeper than that. We believe in the beauty and transformative power of the night sky. More of us ought to be able to see the stars without having to drive 20 or 50 miles out of town. Light pollution shreds our connection with the universe. And much of the problem is simply the result of ignorance about the connection between poor lighting and the disappearing night.

In a nutshell, this is what you’re looking for in good lighting. IDA/PSATS

Fixtures that are boxed (shielded) and point their light down to the ground where we need it to find our way are good. Lights that shine out and up are rarely necessary. You can make a difference at your own home by purchasing a “night-sky friendly” porch light (one that shines the light down and not in your face) from the local hardware store. Then take the next step and talk to your town board or city councilor. Tell them you want to make driving safer and more comfortable and keep the skies dark, too, so kids can grow up seeing stars and planets. Lots of citizens have worked with their city governments to craft lighting ordinances. Many city governments invite public commentary before new buildings or projects are begun. Be a voice for wise use of lights.

For more information on good and bad lighting, success stories and help in crafting a lighting ordinance, check out the International Dark Sky Association (IDA) website. Clear (and dark!) skies!

9 Responses

  1. caralex

    What I hate while driving at night are those dazzling blue/white headlights on oncoming cars. They cause a moment of temporary blindness which could be very dangerous. I really believe they’re a hazard and have no place on a car. Would you agree?

    1. astrobob

      Hi Carol,
      Oh gosh, yes. It’s an arms race as far as headlights go. Soon every car will have them. My guess is that car manufacturers won’t do anything about the glare until customers start routinely complaining about them or until a better technology comes along.

  2. Edward M. Boll

    That probably explains partly why I have not seen a good northern loights display since the 90’s. My youngest Great Great Grandpa retired nearly a century ago from farming. I can just kind of imagine how the unlit sky looked to them back then. If we could transport ourselves in time, I think that we would be amazed.

    1. astrobob

      If people only cared more deeply about what they were missing. I think most people tend to consider a dark sky something you experience once in a while on a camping trip.

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