Some terms from the world of science and sustainability are not so easy to understand. But don’t worry – in our new series “Simply explained”, we break down complex topics and technical terms into understandable words. This makes science accessible, entertaining and exciting for you!
What is light pollution?
Light pollution, also known as light smog, is a special type of environmental pollution. The night sky is brightened by artificial light. A source of light pollution is any light that shines outside at night or dazzles through window panes.
Is there such a thing as a completely dark night?
There has been a natural and subtle basic brightness of the night sky since the Earth was formed. This basic brightness is created by the light from stars, the moon, the planets and the Earth’s atmosphere – this is known as “airglow”. There is therefore no such thing as a completely dark night on our planet, so the night is not 100% dark even in the darkest places in the world.
Are the nights getting brighter?
Light is virtually everywhere and has become an integral part of our world. In public spaces, there is lighting for streets, soccer pitches, night ski slopes, open-air events and concerts. But advertising lighting and decorative lighting on houses, façades, bridges and trees also make up a large proportion of light sources. In addition, the brightening of the night is intensified by every further technological development – such as LED technology. Useless or misdirected permanent lighting, lights with many blue components or excessive brightness as well as excessive advertising and decorative lighting cause a particularly high level of light pollution.
Why is light pollution a problem?
Light pollution therefore means that the natural brightness of the planet is polluted by artificial light. And this is problematic for various reasons. Almost all organisms on this planet rely directly or indirectly on light as their strongest zeitgeber. The light/dark rhythm has been firmly anchored in living organisms for billions of years and controls vital processes such as waking and sleeping phases as well as cell repair and cell regeneration. As a result of light pollution, this rhythm is becoming increasingly out of sync.
In diurnal creatures such as humans, the disruption of night-time rest can sometimes lead to sleep disorders or sleep deprivation, which in turn can cause illness. On Earth, around 60 % of all living creatures are nocturnal. Light pollution increasingly disturbs nocturnal creatures in many activities, such as pollination, reproduction or foraging. They are either irritated, displaced, dazzled or distracted by the abundance of light. Insects in particular, such as nocturnal butterflies, are at great risk from light. Plants can also be disturbed in their rhythm and develop frost damage, for example.
In addition to pollination, which is put at risk by light pollution, human health is also directly affected. This is because too much artificial light at night can cause sleep disorders and, as a result, inhibit the dark hormone melatonin. So if you sleep badly at night, this may also be due to the bright, bluish artificial light you were exposed to before going to bed. In addition to the effects on our ecosystems and human health, light pollution also leads to the loss of the starry sky, which we can almost only admire in really dark places and far away from large cities. Last but not least, lighting and thus light pollution causes a lot of CO2 and high costs for our society every year.