Nature Nearby: Raiders of the lost dark
BY FRED SEITZ — In mid-August, I went in my backyard about 3 a.m. to watch the Perseid meteor shower. While I did see several dozen meteors on the clear and pleasant night, I was surprised at how much glare was in the sky at that time. The meteor shower was less impressive than the one I’d seen in my backyard about 10 or 12 years ago. While the “intensity” or showiness of the showers varies yearly, the 2016 shower was heralded as one of the most impressive ones in the past decade, but that was not my personal experience with the recent shower.
While light pollution is far from a new concern, my experience with this year’s Perseids prompted me to explore further. I am old enough to remember that looking skyward on a clear night used to enable one, even in the suburbs, to catch a view of the Milky Way. Current literature suggests that more than 50 percent of U.S. citizens under age 30 have never seen our galaxy, the Milky Way, in their night sky.While we are all familiar with the adage, “like a moth to the flame,” even a casual glance at our local street lights at night shows the gatherings of moths and other insects swirling around them. While this situation yields a nightly bounty for bats, it increases the predation of these nightly flying insects and reduces their chances for pollinating plants and meeting Mr. or Ms. Right.
Some people may have less emotional attachment to moths, but light pollution has deleterious effects on some species that have more emotional and functional appeal for humans. Birds use stars to navigate, and the glare and the glow of light pollution has caused many birds to crash into illuminated buildings. Lighting has also altered the migration of Atlantic salmon (a species near and dear to many of our tummies). Many mammals sleep during the day and hunt at night; the obverse condition with brightly lit nights has adversely affected their behavior as well. Frogs often call for mates at night, and the excessive illumination also can disrupt their behavior, as well as that of other amphibians.
Purdue University has studied how night lighting can also affect trees and other plants. They observed how night lighting alters when plants are photosynthesizing and when they are dormant. They determined that the lighting may extend their growth, which, in turn, may make them more susceptible to damage when colder, harsher weather arrives. Night-blooming plants, which often attract their pollinators by scent, may also not fare as well with night illumination.
While those who have studied the impact of light pollution recognize that elimination of night lighting is not realistic or probable, they do cite how night lighting could be readily improved by shielding that directs light downward for use by people. The use of certain types of illumination (fluorescent, mercury vapor) can reduce negative environmental effects, as well as reduce the cost of illumination by nearly $2 billion annually in the U.S., according the International Dark Sky Association.
If these impacts on environmental health and economic costs were insufficient concerns, light pollution has also been found to have adverse effects on human melatonin, disrupt circadian rhythms, and increase the risk of breast and prostate cancers.