Artificial light allows us to operate in a 24/7 world but the technology also disrupts and distracts animal species that rely on dark skies. Photo by Storyblocks.


May 22, 2024

Reporter Marshall Hinsley talks to Michael Rymer of Dark Sky International and Cindy Luongo Cassidy of Dark Sky Texas about how artificial light is harming the natural world and ways we can reduce our impact. Listen to the podcast produced by Green Source DFW or read the transcript below.

For more statewide environmental news, go to Texas Green Report



Light as pollution, in this episode of the Texas Green Report.

A production of Green Source DFW and the Memnosyne Institute. 

I'm Marshall Hinsley. 

Artificial nighttime lighting illuminates our pathways, enhances our security, increases highway safety, decorates our homes and helps us to communicate. But turning night into day also has an extensive list of unintended consequences. 

A little more than a hundred years ago when the first modern light bulbs began to be mass produced and affordable, no one needed to be convinced that lighting our homes and public spaces was desirable. 

We are a species reliant on our eyes, and our eyesight needs bright light to function at its best. 

Over the decades, we've enthusiastically embraced the opportunities that come from beating back the darkness of night and claiming the entirety of each day for our purposes. Because of cheap artificial lighting, we can work a late shift, go to an outdoor event, make an after dinner run to the grocery store and enjoy any number of activities with no regard for when the sun sets. 

Modern life and the world economy are wholly dependent on our having the full 24 hours of each day at our disposal. 

But in turning on the lights to countless parking lots, highway interchanges, city streets, roadside billboards, store signs, front porches and back alleys every evening, all over the planet, we have collectively created a chronic disruption event for the animal species that rely on dark skies. 

Michael Rymer is a program associate for Dark Sky International, a nonprofit that's shedding the light on the harms of nighttime lighting, and he says that the endless appearance of Dawn that emanates from city streets each night harms birds, bats, moths, amphibians — wildlife that provides us with ecosystem services that we all depend on. 


There's a lot of research still being done, but the obvious is these diurnal and nocturnal species who rely — these wildlife pollinating species like birds and insects, that depend on the night sky to migrate, to feed, to hunt, to mate — all these things that these species also evolve being able to do at night, based off of, under the cover of darkness, or the navigation using celestial objects — stars and moon — that we have ripped away from them. We have blurred their vision of the night sky, took away their darkness, made it difficult for them to live, to thrive.  


Rymer cites research that reveals that skies are now thousands of times brighter at night than they were two centuries ago. Because of this, hundreds of millions of migratory birds die each year during spring and fall migrations as they're lured to the false sense of safety of bright cities where they fall victim to predators, collide with structures or simply become too disoriented and too dehydrated to return to flight. 

A pair of northern flickers were among the carcasses found during a 2021 survey in downtown Dallas. Below them are the remains of American woodcocks and yellow-breasted chats. The migrating birds were presumed to have crashed into buildings following disorientation from bright city lights. Photo by Sean Fitzgerald.

Bats are also affected with some species preferring lights while others shun them, thus creating an imbalance in their species distribution and feeding territories. 

Frogs have more difficulty finding mates and are more exposed to predators in light polluted areas. 

Moths are drawn to bright lights and away from night-blooming flowers.  

The downstream effects, Rymer says, amount to a reduction in the ecosystem services that each of these species offers us, such as pest control, crop pollination and the simple joy of sharing this planet with a diversity of animals. 

These are just a few examples of the species affected by light pollution, and research into plants has found negative effects on trees and wildflowers too. 

As for humans, research suggests that excessive artificial, nighttime light raises the risk of sleep disorders, obesity, diabetes, heart disease and cancer. There's also a less tangible effect on the human mind. 


In North America and Europe, it's close to 100 percent. It's between 90 and 99 percent of people live under light polluted skies. They don't see the Milky Way from where they live. And this is a tremendous loss in that our species has evolved over millennia, knowing the night sky, having a connection to it, not just a spiritual one, but a practical one. How we told seasons and, you know, when to grow our food, when to harvest, how to navigate, where to go — all these things we've of course advanced our technology to where we don't need it, but, you know, that just goes into how much we've lost of our connection with the world. 

And so, especially in America, North America and Europe, we really have no clue anymore. Some people don't know what a dark sky looks like — what that even is. 


Although there's no returning to black skies full of stars that are visible from horizon to horizon. Rymer says we must nevertheless begin to scale back the amount of light that we waste and give more thought to how we use light in the first place. 


Light pollution is one of those problems where, it is a pollution, and a lot of people don't maybe see it that way right now, but the increased awareness into the public consciousness shows that it is being thought of as any other type of pollution, which means it is an excessive amount of artificial waste in our natural environment, and it takes the form of light. 

And, you know, our world evolved over time of, one, being separating light and dark from night and day. And here in the past century and a half or so, we introduced this artificial light, and the means of electricity, and we have really just overdone it in the places where we live. And so we have flooded our natural nighttime with so much light that it looks like twilight throughout all hours of the evening. And it takes a huge toll on our environment and how we kind of commune with the natural world. 

A lamppost's downward-turned cover reduces light pollution. Courtesy of Dark Sky International.


Board President of Dark Sky Texas, the Texas chapter of Dark Sky International, Cindy Luongo Cassidy says we can reduce almost a third of the light pollution we create by simply ceasing to flood light into open fields and up into the sky. 


People need a certain amount of light for our activities at night. But we don't need as much as we tend to use. And we certainly don't need to send it over into empty fields or even empty parking facilities where nobody is at three o'clock in the morning. 

We don't need to send it up into the sky. In fact, it's estimated that about 35 percent of light is wasted — of the artificial light that we use at night, and that amounts to about $3 billion worth of energy that's lost every year. 


Dark sky international has worked with lighting engineers and lighting manufacturers to create guidelines on smarter lighting. 

The five principles of the guidelines are: 

1.  Determine the usefulness of the light in an area being considered. Think about the effects it'll have on wildlife and determine if alternatives such as reflective paints or signage may be used instead of a permanent light. 

2. Target the light. Use a shielded fixture to make sure that the light falls only where it's needed, aimed toward the ground. 

3. Choose the dimmest light that still gets the job done. 

4. Control the light with a timer or a motion detector and have the light turn off when it's not needed. 

5. Choose warmer lights toward the yellow part of the spectrum, avoiding white and bluer lights as research shows that warmer colors of nighttime lighting cause less harm to animal species. 

The Lights Out Texas campaign is currently urging Texans to turn off outdoor lights from 11 p.m. to 6 a.m. until June 15. Courtesy of Texas Conservation Alliance.


When we do these five principles, you will have plenty of light. It's just smarter lighting, completely. When you do that, when you follow these five principles, you save money. 


The organization recognizes parks, urban spaces and communities for adopting smart lighting practices, and Texas has about two dozen such places to be proud of. 


Some of those are parks. Some of those are cities and on our Dark Sky Texas website, you can go and click on at the top, Texas Dark Sky Places and you can have an interactive map of some of those places. 

Some of the cities that are working on it are obviously — the city of Dripping Springs was the first one in the state to be so designated, and that gave a lot of impetus to other people in the area. We've got the city of Horseshoe Bay. We've Wimberley Valley, which is Wimberley and Wood Creek. We've got Lakewood Village up north of Dallas. We've got the city of Fredericksburg. We've got the city of Blanco and the city of Bee Cave. 

As far as cities go, we also have several developments of distinction: Sierra La Rana out in West Texas, a Lost Creek development and River Hills neighborhood, both in the Austin area. 

Then for our parks, we have, of course, Big Bend National Park. We have Copper Breaks State Park, We've got U Bar U Camp and Retreat Center, South Llano River State Park, Big Bend Ranch State Park. 

Now both Big Bend Ranch State Park and Big Bend National Park are part of the bigger area that is now called the Greater Big Bend International Dark Sky Reserve. And that is a much larger area all the way up around McDonald Observatory, but it also goes into Mexico. So, all of that area has agreed to control their lights and anything that new goes up is following these five principles. 

We have Devils River State Natural Area, Milton Reimers Ranch Park, Lyndon B. Johnson National Historic Park, Black Cap Wildlife Management Area. All of these are International Dark Sky places in Texas, and then if you weren't counting, there were 21 of them. 


For the Texas Green Report, I'm Marshall Hinsley. 

For more statewide environmental news, go to Texas Green Report



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