Lesson Fourty-Six: Light Pollution
On a clear night in 1994, an earthquake caused a city-wide power outage in Los-Angeles.
Startled awake, some residents who had stumbled outside called emergency centres to report a mysterious cloud overhead.
That weird cloud, was the Milky Way which had long been obscured from view by the city’s lights.
For those of you who don’t know, Light Pollution is an inappropriate or excessive use of artificial light including glare, or intense brightness which drowns out the night sky over urban areas.
AKA When too many lights are waaaaay too bright.
While the invention of electric lights revolutionized how humans live on this planet, the toll on related systems (like wildlife and human health) is becoming harder to ignore.
Photo Source: NASA
Global night-time photos like this look gorgeous, but they further illustrate how wide-spread light pollution is.
Speaking of cities filled with light, let’s see if you can take a guess at this question:
IMPACTS OF LIGHT POLLUTION: HUMANS
Humans have a long history of living in darkness at night.
As our bodies need sunlight for health, they also need the darkness to complete our circadian rhythms and produce the vital chemicals we need to survive (eg. melatonin).
Due to these kinds of circadian disruptions, the World Health Organization (in 2008) actually declared night shift work a risk factor for cancer.
Similarly, in 2012, the American Medical Association warned that pervasive use of nighttime lighting “creates potentially harmful health effects and/or hazardous situations.”
IMPACTS OF LIGHT POLLUTION: WILDLIFE
Just how light impacts our rhythms and cycles, light does the same to mammals, birds, and reptiles.
The very recent arrival of the powerful artificial light has dramatically (and negatively) affected animal behaviours in mating, migration, sleeping, and hunting. For example:
🦆 Migrating Birds: Artificial light can cause them to wander off course and into lit buildings
🐢 Sea Turtle Babies: They hatch at night on the beach and find the sea by finding the bright horizon - unless distracted by artificial lights.
🦉Predators & Prey: Predators have adapted to using darkness to hunt, and prey species use the dark as cover
Click here for more examples.
IN CONCLUSION
While electric light has been helpful for advancing our species, it has messed with thousands of years of evolution - for ourselves and our surrounding wildlife.
Let me know if you have any follow up questions or thoughts about the lesson! Similarly, tune in next week when we cover a similar lesson: Noise Pollution.
