5 Types of Light Pollution and Their Environmental Impact

Public Domain. Detail "Four Times of the Day" by William Hogarth, 1736. (Wikimedia Commons)

From radically disrupting ecosystems to increased CO2 emissions, light pollution goes far beyond just eliminating our view of the stars.

The night time prior to artificial lighting is pretty hard for most us light-guzzling moderns to grasp, but as Jon Henley writes in The Guardian, “The pre-industrial night ... was widely regarded with dread and fascination in equal measure.”

Before our nights were drenched with light, people relied on other strategies to navigate their worlds; the moon and stars were valued for their practical luminosity, people knew their neighborhoods and homes intimately, senses were more finely tuned since sight was hampered. It was scarier and more dangerous, writes Henley, but also had its charms.

Nowadays, the western world has light in spades. So much light that we’re drowning in it. A little light would be great, but we overuse it to embarrassing excess. Consider this from the IYA2009 Cornerstone Project, a collaboration between the International Astronomical Union, UNESCO and the US National Optical Astronomy Observatory:

Light pollution wastes money and energy. Billions of dollars are spent on unnecessary lighting every year in the United States alone, with an estimated $1.7 billion going directly into the nighttime sky via unshielded outdoor lights. Wasted lighting in the US releases 38 million tons of carbon dioxide into the atmosphere annually; unshielded outdoor lights are directly responsible for 1.2 million tons of carbon dioxide waste. Simply reducing and removing unnecessary lighting saves money and energy, often at minimal expense. Over-lighting the night neither improves visibility nor increases nighttime safety, utility, security, or ambiance.

Light pollution comes in five forms:

Urban Sky Glow 

While it sounds kind of poetic, the brightening of the night sky over inhabited areas is actually responsible for the disappearance of the Milky Way and stars from many areas. As IYA2009 points out, “increasingly, the most important equipment needed to enjoy the wonders of the night sky is an automobile with a full tank of gas and a map.”

Light Trespass

Noise complaints aren’t uncommon, but how about light complaints? This might happen with light trespass, when unwanted light enters private property, be it from a neighbor, passing headlights, or street lamps.


This often overlaps with urban sky glow and occurs when excessive light is used to bring attention to an important building. Landmarks, historic buildings and attention-seeking skyscrapers come to mind.


When unshielded light from one source spills into the sky and elsewhere; glare can reduce visibility and can be blinding.

Light Clutter

Excessive groupings of light that are bright and confusing, commonly found in over-lit cities and inhabited areas. The proliferation of clutter contributes to urban sky glow, trespass, and glare.

UK-based LED lightbulb site, LEDLights.co.uk, created this infographic that explores how these forms of light pollution effect the planet.

light pollution

© LEDLights.co.uk

The impact the problem has on wildlife is especially disturbing – well it's all disturbing. But as I've said before, darkness is an easily renewable resource, we just have to turn off some lights. A little dread and fascination might do us some good.