Dark Skies
As a landscape designer I am tasked with being a steward of the land. I take this role very seriously and strive to protect the earth from harmful substances and destructive landcare practices. What I did not realize, however, is that I also need to be a steward of the dark skies in my practice and with my personal habits. Our dark skies are disappearing because of a careless over use of artificial light. This is as disruptive to the ecosystem as unsound landcare practices.
Our dark skies are not just for star-gazed lovers. Our dark skies are a precious resource encoded in the DNA of all living beings. Plants and animals depend on earth’s daily cycle of light and dark rhythm to govern life-sustaining behaviors such as reproduction, nourishment, sleep and protection from predators. Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day. “Predators use light to hunt, and prey species use darkness as cover… Amphibian breeding rituals such as the croaking of frogs and toads can be disrupted by artificial light, resulting in declining populations. Birds that migrate or hunt at night navigate by moonlight and starlight. Artificial light can cause them to wander off course and toward the dangerous nighttime landscapes of cities. Every year millions of birds die colliding with needlessly illuminated buildings and towers.” (1)
We have all seen insects franticly hovering around the glow of artificial light, a fatal attraction that has lead to declines in insect populations. Insects are a critical link in the food and pollination web. Nocturnal pollinators don’t always get the credit they deserve. Agricultural crops are not only pollinated by diurnal pollinators such as bees and birds, but also by nocturnal pollinators such as moths. Out of sight should not mean out of mind. Our less visible nocturnal pollinators depend on dark skies to do the work they do for us in bringing food to the table and in maintaining the ecosystem of our planet.
Darkness is essential to human health. In 2017, the Nobel Prize in medicine was awarded to Jeffrey C. Hall, Michael Rosbash and Michael W. Young “for their discoveries of molecular mechanisms controlling the circadian rhythm.”
“With exquisite precision, our inner clock adapts our physiology to the dramatically different phases of the day. The clock regulates critical functions such as behavior, hormone levels, sleep, body temperature and metabolism. Our wellbeing is affected when there is a temporary mismatch between our external environment and this internal biological clock, [and there] are also indications that chronic misalignment between our lifestyle and the rhythm dictated by our inner timekeeper is associated with increased risk for various diseases.” (2)
What about safety concerns at night. How can we balance safety with darkness? Outdoor lighting is intended to enhance safety and security at night, but too much lighting can actually have the opposite effect. Visibility should always be the goal. Glare from bright, unshielded lights actually decreases safety because it shines into our eyes and constricts our pupils. This can not only be blinding, it also makes it more difficult for our eyes to adjust to low-light conditions. (3) And, there is no clear scientific evidence that increased outdoor lighting deters crimes. It may make us feel safer, but has not been shown to make us safer.
How can outdoor lighting be used responsibly? As a landscape designer, I have great influence with my clients in guiding their selection of appropriate landscape lighting. I can suggest lighting that is energy and cost efficient, yet ensures safety and security, protects wildlife, and promotes the goal of dark night skies. Suggestions include:
Always choose fully shielded fixtures that emit no light upward.
Use “warm-white” or filtered LEDs (CCT < 3,000 K; S/P ratio < 1.2) to minimize blue emission.
Look for products with adaptive controls like dimmers, timers, and motion sensors.
Consider dimming or turning off the lights during overnight hours.
Avoid the temptation to over light because of the increased luminous efficiency of LEDs.
Only light the exact space and in the amount required for particular tasks.
Lastly, it is important to remember that dark skies belong to all of us. We are washing away the wonder of the cosmos for this generation and all generations to come if we continue the trend of the over use of artificial light. Ask any millennial you know if he or she has ever seen the Milky Way, the North Star, The Big Dipper, The Little Dipper or any of the constellations. I have asked the question, and it was stunning to learn that this generation has been robbed of this cosmic connection that marks our place in the universe. Put it on your bucket list to visit an International Dark Sky Sanctuary, Dark Sky Park or Reserve with your children, or students or clients. Educate yourself on the importance of preserving the Dark Sky and learn how you can protect and influence others to protect the dark skies. Visit http://www.darksky.org/ to learn more.