The winter solstice, the darkest day of the year, is already two weeks behind us. I thought it would be a good time to reflect on that darkness which is now diminishing by the day. Of course our inclination this time of year is to extend these too-short days with light. But at night, I find myself craving the darkness that goes along with a cold winter sky. And I resent the intrusion of the floodlight that shines through the thin shades of my windows from the property next door.
Yes, I could get thicker shades, but the floodlight is indicative of a much larger, often ignored issue: light pollution. There’s even a name for that unwanted, unnecessary light: light trespass, and it happens not just from one backyard to the next but on a global scale, as any satellite image of the Earth at night will show.
The rate of brightening over U.S. skies is said to be 5-10 percent annually. Dark skies are now a commodity, with national parks and communities receiving a special designation from The International Dark-Sky Association if they meet certain standards of darkness.
The problem with so much light is that no living creatures, ourselves included, have evolved to live in an artificially-extended day. It messes with our circadian rhythms. Too much light at night suppresses our bodies’ production of melatonin, correlating with health issues, higher rates of breast and prostate cancer.
Artificial light disrupts all kinds of biological functions in animals. Frogs, for instance, may curtail their nightly chorus, leading to diminished breeding. Much publicized is how the hatchlings of endangered sea turtles get lost and disoriented from bright beachfront strips, never making it to the ocean. Normally, the just-hatched turtles crawl to the ocean because in the moonlight, it is the brightest thing around, but no longer.
Birds are particularly vulnerable because they migrate under darkness, relying on the presence of the stars and their own magnetic compass. Lights can disorient them and trap them, causing them to expend their precious migration energy trying to navigate out, and sometimes collide with buildings and towers to the tune of perhaps 100 million birds a year in North America.
The chances of birds becoming disoriented by lighted structures increases when the night is overcast or foggy, because the stars are obscured. Then, “they will orient to almost any elevated light source to attempt to navigate,” said a Division of Natural Resources spokesman in response to a 2008 incident in West Virginia in which hundreds of songbirds died from slamming into a high school. The night was foggy, and the lighted building, which sat atop a hill, had apparently attracted the birds. When people arrived early that morning, the birds, mostly yellow warblers, were fluttering and banging into the windows.
Even when birds aren’t migrating, they are still susceptible to ambient light pollution. They may start singing well before dawn or lay eggs earlier, causing subtle mismatches in timing. Researchers at the Max Planck Institute for Ornithology in Germany stated in 2010, “Our findings show clearly that light pollution influences the timing of breeding behavior, with unknown consequences for bird populations.”
When birds lose the cover of total darkness, they may be more visible to predators. Also, nocturnal hunters like owls, adapted for seeing in the pitch dark, may actually lose their advantage.
This insidious form of pollution is, however, remarkably fixable. It isn’t regulated by the EPA, but many cities are participating in initiatives to shut off lights in tall buildings when not in use.
The International Dark-Sky Association estimates that a third of all lighting in the U.S. is wasted. That’s $2 billion a year, or 14.1 million tons of CO2 per year of wasted fossil fuels, which compounds air and water pollution and climate change, all stressors for birds.
While the Berkshires are relatively dark, many neighborhoods are plagued with bad lighting — excessive, unnecessary lights that shine up and out, creating that coppery haze over populated areas.
Aside from shutting off excessive lights, the easiest fix is simply to install lights that are covered and that point down — the lights shine down on the ground, where they are needed, and stay there, actually increasing visibility because no one is blinded.
One of the joys of living in a largely rural area is supposed to be the darkness of the sky, the sharpness of the stars on a clear winter’s night. We may not need the moon and stars to navigate any more, but there’s something satisfying — and healthy — about sleeping in the dark, letting the moonlight come in.
