Darkness Illuminated
Long winter nights are a good time to contemplate benefits of the dark.
Upon arrival in the desert this year our airport driver was a Belgian immigrant who, in the course of conversation, lamented the light pollution that has claimed so much of the Coachella Valley. In one particularly egregious example, he spoke of a golf course near where he lives that is entirely lit for night play. He said they often find dead birds there in the morning, which he attributed to this unnatural condition.
My attempts to check this information came up with a municipal course in Indio that is indeed lit at night. In addition, a golf course in Indian Wells offers illuminated targets for a “Shots in the Night” experience.
No word on dead birds or any effects on wildlife, so the jury will stay out on that one. Still, I don’t imagine anyone involved in these golfing activity gave nature a second thought.
Fortunately, there are scientists working on the effects of light pollution on ecological systems, and their studies suggest we ignore light pollution (what scientists, with their love of acronyms, call ALAN—artificial light at night) at our peril.
At Puddock Hill we both contribute to light pollution and fight it. In part we intend the trees and shrubs we’ve planted to wild our edges to block out light from neighboring houses. We have resisted temptation to set permanent lights along the driveway or at the front gate (the light on our Ring camera does snap on there at times) or by outbuildings, which would be conventionally pretty. And we only turn on the path lights of the patio garden during special occasions. As a consequence of these actions (or non-actions), plus the fact that the nearest neighboring houses stand a considerable distance away, parts of the property enjoy genuine darkness at night.
On the other side of the ledger, we do light the front steps and the area by the back door for safety. If I could lay down one lighting rule that offers a reasonable compromise with nature, it would be “light for safety, not for aesthetics.” Leave nature the beauty of its primeval darkness.
My awareness of light pollution’s harms comes from a concern for the fewer and fewer fireflies we see—a decline that has been well documented in many localities. But it turns out that’s not the half of it.
Last October, “Philosophical Transactions of the Royal Society B” (I think the B stands for biology) devoted an entire issue to “Light pollution in complex ecological systems,” the thrust of which was an attempt to broaden our understanding of how the effects of artificial light extend well beyond a few isolated species.
Skeptics may wonder how big a deal this must really be. They should consider, as the Royal Society paper notes, that “Organisms of most forms have adapted to using light as a source of energy or information.” Unnatural interventions can disrupt these activities.
Of course, plants, algae and cyanobacteria use light for photosynthesis, making them “primary producers” of energy. Information provided by natural light is equally important to other species that evolved over millions of years. The report’s summary notes:
From a biological perspective, natural light regimes, in contrast to other environmental conditions such as temperature, have remained more or less consistent over aeons of Earth’s history. This makes light pollution a novel perturbation to which organisms are unlikely to have evolved the ability to cope with change. Thus, it is not surprising that ALAN has the potential to fundamentally disrupt physiology and behaviour of many organisms.
As summarized in a recap from phys.org entitled “Even low levels of artificial light disrupt ecosystems”:
Key findings include the ability of artificial light to:
reach belowground soil communities, impacting soil basal respiration and carbon-use efficiency
influence invertebrate activity, which was linked to higher predation rates at night
reduce plant biomass and diversity, as well as change plant traits, such as leaf hairiness
potentially shift—homogenize—the periods when species are active, leading to increased overlap and ultimately threatening species persistence.
I was surprised to learn that artificial light can impact underground communities, which only reaffirms my belief that we too often ignore the effects our actions have on the soil beneath our feet.
But perhaps the most impactful disruption for the backyard steward is increased predation associated with artificial light. Where we do have persistent illumination at night at Puddock Hill, toads gather to eat insects attracted to the light. This may benefit the toads at the expense of the insects (we love our toads so much that we named the place after them!), and while it’s hard to sympathize with a bunch of bugs, it’s worth reminding ourselves that they constitute an essential part of the food chain.
Meanwhile, we’re likely not to notice millions of other dramas playing out in nature: the amphibians and fish and birds and small mammals exposed to predators 24/7 due to our compulsion to light the night.
The area where we have our desert house is almost completely developed on the valley floor. On a recent trip to a less densely packed agricultural region in the southern part of the valley, we received a reminder of what true darkness might once have felt like in parts closer to home. While irrigated date farms and vegetable crops have replaced sand-blow desert, they of course don’t require artificial light. Here’s what we saw just before sundown:
You’ll note a few lights above, but not many.
No more than a hundred years ago, the more developed parts of the valley also bathed in natural darkness at night, but now there are roads and houses and strip malls, all lit to some degree when the sun goes down.
There are also around 125 unlit golf courses, one of which abuts the back wall of our small property. No doubt inadvertently, this expanse of green and others like it provide a refuge of nocturnal darkness for which we should be grateful. The wild things certainly must be.
Nature would thank us profusely if we’d turn off more lights.
Baja passion vine (Passiflora foetida v. longipedunculata), a native of Mexico, flowers on our arbor:
