Light pollution may seem like a less serious form of waste than its notorious toxic or chemical cousins, but a map like this showing the amount of light reflected up and away from the planet at night indicates clearly just how much wasted light we actually generate. All this light at night places an obvious strain on our over-taxed electrical grid, but the variety of other consequences, above and beyond the electricity issues, can be more serious than we might realize.
First of all, anyone who has tried to see the stars from a city at night is familiar with one adverse effect. In much the same way, night-time light pollution negatively impacts a wide variety of animals which rely on the darkness, interfering with the mating and feeding patterns of wildlife of all kinds, most notably zooplankton, moths, sea turtles and salamanders, and a variety of night-blooming flowers.
During migration, a number of different kinds of birds are attracted into cities by the bright lights of skyscrapers, where they become disoriented, lose their way, and often collide with the buildings which lured them in. In just one city, tall, brightly lit buildings will kill millions of nocturnal birds every year. Turning out the lights in your office before going home, just for example, can make a difference.
Finally, incredibly, it has recently been discovered that light pollution is responsible for an increase in instances of breast cancer in humans. It’s not only moths and turtles who are fooled by the daylight-like conditions we provide for ourselves at night; we’re confusing our own bodies as well. Melatonin, a hormone that regulates sleep-wake cycles and is produced in the darkness of night, has been unambiguously linked to higher rates of breast cancer when not produced in big enough quantities.
Keep your porch light off at night. Ditch the floodlights at the cottage. Even install a timer. Less night-time light pollution is good news for animals of all kinds humans included.