A bright world

It is common knowledge that humans influence our environment heavily. The anthropological impact is visible in many ways. Especially the topic of pollution is a symbol of anthropological impact for many. We can see the damage in air pollution, water pollution, or even in noise pollution. A type of disturbance we rarely think about is caused by one of humankind’s most precious inventions – electronic light. Light pollution is a widely unknown threat to human health and our environment.

“Light pollution” describes the presence of unwanted or excessive artificial light, especially at night-time. It is a factor that unmistakably comes with the process of urbanization and industrialization. Even though the presence of artificial light is a sort of precaution to ensure safety in the dark night, especially in the city humans tend to overuse light. Light is used for decoration like the exterior and interior lighting of buildings, for advertising, commercial properties, offices, factories, and illuminated venues. According to estimations, more than 83 % of the world’s population live in a light polluted area. The pollution can be defined into more specific acts of light disturbance. Skyglow is the phenomenon of a brightened night sky. Glare describes excessive brightness in lights, that may cause visual discomfort of limitation of vision to humans. Especially in heavily illuminated areas like cities, another component, light trespass can be found. This component characterizes light, brightening an area, that is not supposed to be illuminated. Sadly, this is a common problem in unsuitable types of lightning, which can be seen when useful sources of light, like streetlamps, illuminate other areas due to unfortunate design.

Artificial light imitates sunlight, which is one of the reasons why light pollution is harmful to humans. Said artificial light interrupts the circadian rhythm – our internal clock that guides our day and night activities as well as running physiological processes in our bodies. Furthermore, the “fake light” disturbs the natural melatonin production that is heavily linked to brightness and darkness. The resulting suppression of melatonin production and the interrupted circadian rhythm can not only lead to sleep disorders but to other problems regarding one’s health. Common health problems like headaches, worker fatigue, medically defined stress, and even anxiety have been linked to artificial lightning.

Not only humans experience health-related problems because of artificial light. Many animals are nocturnal and therefore sleep during the day and are active at night. The artificial light interrupts their rhythm by altering the night-time environment. Light pollution disturbs the natural hunting dynamic of prey and predator. While predators benefit from artificial light, prey animals struggle to hide when the night is unnaturally illuminated. Furthermore, research has proven that amphibians are influenced by light pollution. Certain species, such as the male green frog population show different behaviour during the breeding season, which might show negative outcomes on the number of offspring.

Moreover, the current use of artificial light is a large waste of energy. While artificial light negatively influences the environment by interrupting the natural habits of wildlife, it furthermore damages the environment by heavily contributing to climate change.

At this stage of light pollution, it starts to threaten scientific research. Due to the phenomenon of “skyglow”, caused by artificial light, the night sky is brightened, which prevents us from getting a clear look at the starry night sky. The artificial light decreases the “signal-to-noise ratio”, meaning the synthetic light washes out objects in the night sky. Those objects, including galaxies, stars, or nebulae, are of high importance to scientists. Not being able to identify or locate them at any given time, makes the observation of our sky more difficult.

Luckily, there are people taking action. To help recover our dark sky several associations and organizations were founded. A main participant in those actions is the International Dark Sky Association (short IDA). Since 1988 the organization has been actively working on recovering our night sky. As for now, the IDA has designed more than 170 international dark sky places that protect an area of roughly 110 000 sq km of the globe. Furthermore, they support the design of new dark sky-friendly light fixtures.

Tamina Schulze

B.J. Baker; J.M.L. Richardson: The effect of artificial light on male breeding-season behaviour in green frogs,
F. Falchi; R. Furgoni: Light pollution in USA and Europe: The good, the bad and the ugly

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