Animal Senses #14: Unknown Pollutants

The last chapter in Ed Yong’s book, Immense World, is about the pollution we humans cause and its impact on the creatures around us. My initial though was, god, I hope he isn’t going to end this awesome book on a paternalistic, preachy note about industrial pollution and deforestation…

 

I needn’t have worried, because Yong does not talk of CO2, global warming, deforestation, poaching and the likes. Wait, so there’s other damage we do? Yes, it involves stuff most of us don’t even realize is a form of pollution too.

 

The first one is light pollution. Yes, light can be a form of pollution.

“It is jarring for us to think of light as a pollutant, but it becomes one when it creeps into times and places where it doesn’t belong.”

After all:

“Light at night is a uniquely anthropomorphic phenomenon.”

Until we lit up the planet, the “daily and seasonal rhythms of bright and dark” were fixed. Physicists knew this problem for long – it prevented them from seeing the universe – but biologists discovered this only as recently as the 2000’s.

 

When sea turtles hatch, they are programmed to move away from the dark dunes and towards the brighter oceanic horizon. But our lit up roads confuse them, often with fatal consequences as they go in the wrong direction to starve and die or get crushed by us. Insects get drawn to street lights, breaking their sleep cycle and endangering them by making them visible to their predators. Insects with aquatic larvae end up laying their eggs on window sills because the reflection from glass at night is confused with reflection from water.

 

Colors matter too. Red light disrupts the migration patterns of birds. Blue light disrupts the body clock of almost all species and is the worst of all. To make matters worse, blue scatters the most as well. But since blue is the cheapest and most efficient light to produce, that is the color we produce the most of.

 

Even worse, the problem isn’t limited to the bigger towns and cities. The spread of the light from these places is over a large distance, even hundreds of miles.

 

The other problem is noise pollution. Even in the reserve forest, “areas are under acoustic siege”. Increased sound levels disrupt the communication of many animals and birds. It also wipes out the noises species look for – the rustle of their prey moving. Every 3 extra decibels of noise we create can halve the range over which natural sounds can be heard.

“Noise shrinks an animal’s perceptual world.”

It can act like an “invisible bulldozer” wrecking through habitats.

“Noise can degrade habitats that look otherwise idyllic, and make otherwise livable places unlivable.”

 

These additional signals we are pumping in – light and sound – are turning the “senses that have served their owners well for millions of years” into liabilities. Sure, species evolve as the environment around them changes, but the speed at which we are changing things is just too fast for evolution to handle.

 

An enlightening and sombre end to one of the best books I’ve ever read.