What is light pollution?
Light pollution, also known as photopollution, is the brightening of the sky in response to excessive use of artificial light emitted from city and residential buildings and structures, traffic lights, advertisements, etc. Throughout history, humans have been obsessed with the creation of light. From the discovery of fire, to gas lights, to electricity, we have been exceedingly successful at illuminating the dark corners of the world, regardless of the position of the sun. However, constant illumination has its drawbacks: light pollution can wash out the night sky, hindering any star-gazing aspirations for city dwellers, street lights can disrupt your night’s sleep, and it can disrupt the natural circadian clocks animals and plant populations (Hölker et al 2010a).
Source: http://luxreview.com/article/2015/08/light-pollution-wiping-out-the-texas-night-sky
What are circadian clocks?
Circadian clocks are present in most organisms, including humans and birds, and respond to natural day-night cycles (Hölker et al 2010a).
Why should we care?
Artificial light at night is projected to increase 6% per year (Hölker et al 2010b). Doesn’t seem like so much? NASA reports by 2025, more than 75% of the area in the United States will be unable to see 100 stars in the sky due to light pollution.
What about the fauna?
Thirty percent of global biodiversity is nocturnal, and the changes in behaviour of nocturnal species will in turn affect the behaviour of diurnal species (Hölker et al 2010a). Furthermore, nocturnal species adapted to low light environments and are extremely light-sensitive (Hölker et al 2010a). These nocturnal species may not be able to adapt quickly enough to artificial light and many nocturnal species may be lost in artificially illuminated areas (Hölker et al 2010a).