Discover the Night
Have you ever vacationed or visited a remote or rural destination and wondered why you felt particularly refreshed or rested afterwards? Have you marveled at the starry skies and thought to yourself “Why are the stars so much brighter here?”
Have you wondered why it has become the norm to leave outdoor lights on through the night and so endanger not only our own nighttime heritage, but also cause serious environmental consequences for humans, wildlife and our planet?
Light Pollution Matters
The nighttime environment is a crucial natural resource for all life on Earth, but the glow of uncontrolled outdoor lighting has hidden the stars, radically changing the nighttime environment.
Before the advent of electric light in the 20th century, our ancestors experienced a night sky brimming with stars that inspired science, religion, philosophy, art, and literature. (Think of van Gogh’s Starry Night.)
The common heritage of a natural night sky is rapidly becoming unknown to the newest generations. In fact, millions of children across the globe will never see the Milky Way from their own homes.
We are only just beginning to understand the negative repercussions of losing this natural resource. A growing body of research suggests that the loss of the natural nighttime environment is causing serious harm to human health and the environment.
Light Pollution Threatens Wildlife
For billions of years, life has relied on Earth’s day-night rhythm to govern life-sustaining behaviors. It’s encoded in the DNA of all plants and animals. Humans have radically disrupted this cycle by lighting up the night. Research shows that artificial light at night has negative and deadly effects on many species.
Sea turtles live in the ocean but hatch on the beach at night. Hatchlings find the sea by detecting the bright horizon over the ocean. Artificial lights can draw them away from the sea, stranding them on land. In Florida alone, millions of hatchlings die this way every year. Many insects are drawn to light, but artificial lights can create a fatal attraction. Think of the fireflies that used to dance around by the millions on lawns in our youth. Or even the bug-splattered windshields of our cars that traversed the nights. Where are they now?
Declining insect populations negatively impact all species that rely on insects for food or pollination. Nocturnal mammals sleep in the day and are active at night. Light pollution disrupts their nighttime environment.
Artificial lights also endanger many bird species. They can disrupt the migratory schedules of birds causing them to leave too early or too late in the season, missing ideal conditions for nesting. Birds that navigate by moonlight and starlight can wander off course. Millions die every year by colliding into illuminated buildings.
Light Pollution Threatens Human Health
Humans are not immune to the negative effects of light in their nighttime spaces. Excessive exposure to artificial light at night, particularly blue light, has been linked to increased risks for obesity, depression, sleep disorders, diabetes and breast cancer.
Light Pollution Wastes Energy and Money
In the U.S. alone, there are about 162 million public and commercial outdoor light fixtures including
- 45 million streetlights,
- 52 million parking-lot lights,
- 62 million lights on commercial buildings.
Residential outdoor lighting isn’t as bright, but there’s a lot more of it — about 1 billion light fixtures.
Lighting consumes lots of energy. In an average year in the U.S., outdoor lighting uses some 120 terawatt-hours of energy, mostly to illuminate streets and parking lots. That’s enough energy to meet New York City’s total electricity needs for 2 years! Excessive light at night causes light pollution and unnecessary greenhouse gas emissions, contributing to climate change.
So, let’s stop wasting so much energy! With so much lighting, even modest efforts to control outdoor lighting saves money, reduces carbon emissions, and helps the environment. We do need some light at night, but much of it is wasted by lights that are overly bright or left on when not needed. Unshielded fixtures waste the most energy. Their light shines upward, instead of down on the ground where it’s needed. At least 30% of outdoor light is wasted. That adds up to $3.3 billion and the release of 21 million tons of CO2 per year! To offset all that CO2, we’d have to plant 875 million trees annually.
But Don’t We Need Nighttime Lighting for Safety & Security?
There is no clear scientific evidence that increased outdoor lighting deters crime. It may make us feel safer, but it does not make us safer. The truth is bad outdoor lighting can decrease safety by making victims and property easier to see.
Glare from overly bright, unshielded lighting creates shadows in which criminals can hide. It also shines directly into our eyes, constricting our pupils. This diminishes the ability of our eyes to adapt to low-light conditions and leads to poorer nighttime vision, dangerous to motorists and pedestrians alike.
What Can Be Done?
The EGT is regularly asked: “What can I do to make a difference?” Well, here is one way that you can make a contribution. The good news is that light pollution is reversible and its solutions are immediate, simple and cost-effective. Here are a few simple things you can do to confront the problem and take back the night:
- Check around your home. Use only fully shielded, dark sky friendly fixtures for all outdoor lighting, so lights shine down, not up, to minimize “light trespass” beyond your property lines.
- Use only the right amount of light needed. Too much light is wasteful, harms wildlife and creates glare.
- Install timers and dimmer switches and turn off lights when not in use. If you must have security lighting, use motion sensors.
- Use only lighting with a color temperature of 3000K and below. This means that there is less blue (cool) light that is more harmful to many animal species.
Check out this resource page on outdoor lighting basics.
Talk to neighbors. Explain that poorly shielded fixtures waste energy, produce glare and reduce visibility. Work with your local governments to ensure outdoor lighting isn’t harming the wildlife in your area.
Become a Citizen Scientist with Globe at Night and document light pollution in your neighborhood and share the results. Doing so, contributes to a global database of light pollution measurements.
[Resources and background materials for this article come from The International Dark Sky Association, a 501(c)(3) non-profit organization based in Tucson, Arizona. For 25 years, it has advocated for the protection of the nighttime environment and dark night skies by educating policymakers and the public about night sky conservation and promoting environmentally responsible outdoor lighting. More information about IDA and its mission may be found at http://www.darksky.org.]