Light Pollution and its Ecological Effects

Some nights are brighter than others, but no matter how bright the stars and the moon may shine, it is always easier for human beings to see during the daytime. This is because we are diurnal and our eyes are most effective in well-lit areas. Of course, nighttime is a significant portion of the day and we can’t always expect to be outside – it isn’t practical. To make our world functional at all times of the day human beings have designed numerous inventions that shine synthetic light.

Unfortunately, the lights and lamps that help us see so easily at all times of the day do not exist without consequence. Although many of our lights stretch taller than the places where we stand or sit and shine down upon us, light itself is still capable of reaching upwards. “Light pollution,” as this phenomenon is known is a very real issue. But what could possibly be such a big deal about releasing harmless light into the sky? Believe it or not, light pollution actually affects the lives of other species including their migration, breeding and feeding habits.

How Light Pollution Affects Us
Have you ever driven down a desolate road far from civilization? The surroundings are noticeably dark. If instead you drive on a road a few miles from a small village, the lights in the windows of the buildings would become more visible the closer you get. However, if you drive toward a big city, the landscape will almost seem to glow with the lights from the many homes and businesses. Why is this significant? Firstly, it alters the appearance of the sky. On the dark desolate road, if you look up into the sky you will see countless stars. You might even see Venus without much trouble. In a city, the sky looks like a chalkboard wiped clean.

Those who don’t care whether or not they see the stars are still affected by light pollution. Human beings need a certain amount of darkness to maintain a circadian rhythm. With streetlights shining in through our bedroom windows and the whole landscape being lit up on our way home from work when it should be dark outside, the rhythm is altered. The body is not ready to sleep at bedtime so even if it does manage to fall asleep, the brain may not be completely at rest. Still, the person must either wake up at a certain time and remain tired throughout the day, or sleep later and fall off rhythm.

How Light Pollution Affects Other Species

The bright lights possibly affect birds the most, particularly nightingales and blackbirds. These species have begun to sing at unusual hours, they have started to breed earlier in their life cycles and their migration schedules are completely out of balance because much more of the day is suitable for hunting. A bird’s migration schedule is crucial to its survival and if they start flying too soon or too late they may not be able to nest. The lights used in cities can also distract birds causing them to crash into buildings or circle around them like insects until they fall out of the sky from exhaustion. Speaking of insects, many types are naturally attracted to light and can be found swarming around streetlights. In response, bats have migrated into cities, following their insect prey.

Aerial animals are not the only ones affected by light pollution. It has also been detrimental to sea life. Sea turtles enjoy dark beaches. It is where they choose to lay their eggs. Unfortunately, many beaches have become overrun by human technology. Artificial lighting lines the beaches while cities, towns, villages and resorts glow twenty-four hours a day. In rural areas you may hear frogs and toads croaking songs all through the night while those that live in bodies of water near cities have no idea when to do so. 

What Can Be Done about Light Pollution?
Unlike other forms of pollution, light pollution is easily rectified. In 2001, Flagstaff, Arizona was declared the first International Dark Sky City allowing its many astronomers to view the night sky with clarity. In the past decade, many other cities and even a few countries have made regulations to do the same. With enough control, most of the sea, sky and terrestrial life can return to normal.

• Fireflies and Lightbulbs: Are lights to blame for the decreasing numbers of fireflies?
• Light Pollution Harms the Environment: Links to papers about how light pollution affects different types of animals.
• Global Assessment of Light Pollution on Protected Areas (PDF): Which countries are causing the problems and which ones are taking steps toward the solution?
• Light Pollution in the United States (PDF): This essay argues that not enough is being done to stop light pollution.
• Studying the Ecological Impacts of Light Pollution on Wildlife (PDF): A report on lab and field experiments pertaining to the subject.
• Environmental Effects of Roadway Lighting (PDF): Artificial lighting keeps us safe while driving, but can there be too much?
• Ecological Light Pollution (PDF): Information on how species interactions have been changed by artificial lighting.
• The Effects of Light Pollution in Hong Kong (PDF): A study to find out if better regulations for light pollution could be put into place in Hong Kong.
• Light Pollution: An online leaflet that serves as a guide to regulating light pollution.