Ecology & Biology

Moth fly to the light, every child knows that. But did you know that birds are also drawn into light beams, often with fatal consequences? Light interferes with the orientation of many animals, some are attracted, some are repelled. Some species try to avoid illuminated areas because it creates a space of fear, the same concept as known from human psychology. One of the reasons is that in the light they are easier spotted by predators. Darkness is an important protection for nocturnal creatures. Artificial “fear spaces” fragment the habitats of many animals, comparable to motorways or concrete jungles.

However, the effect of light goes much deeper. It changes activity rhythms, hormone production, reproduction, growth, metabolism and even gene expression. Thus, light changes the physiology of living beings at the most fundamental level.

Artificial light affects all organisms, even the microcosm

It is not just animals that are affected. All organisms studied so far are influenced by artificial light, including plants and microorganisms. Not always is light negative; some species benefit from longer periods of activity or better perception, but the changed conditions cause entire ecosystems to become unbalanced. We already know of cases where light-sensitive species have migrated from an area.

In today’s concepts of conservation, we mostly consider the conditions during the day. Light pollution is often not an issue. Few environmentalists are aware that the best wetland or the most species-rich bee pasture cannot survive if it is too bright at night. After all, the night is a habitat whose properties must be just as right as the properties of a wetland or meadow. It is a chronotope whose most important property is darkness. If we take away darkness from a habitat, it is just as fatal as if we drained a wetland or cut down a forest.

“Darkness at night is as important as water in a wetland. Without it, organisms cannot survive in the night habitat.”

Annette Krop-Benesch

A toad in the spotlight, surrounded by darkness

As “daytime animals,” we humans often only notice the activities and needs of other diurnal creatures. Since we hardly ever experience natural nights ourselves, we don’t realise that today’s nights are up to a thousand times brighter than natural full moon nights. This can seriously disrupt the behavior of nocturnal animals. And just like humans, diurnal animals also suffer from sleep disorders when it is no longer sufficiently dark at night.

Light pollution: An important but overlooked component in the destruction of our ecosystems

I am often asked how serious the environmental damage caused by light pollution is or how important light pollution is compared to other environmental damage. Isn’t it more important to fight against climate change or plastic waste? This question makes little sense. Light pollution affects all organisms and all habitats, even the deep sea. It is an environmental stressor that weakens organisms, making them less resilient to climate change, pathogens or environmental toxins. All existing environmental problems reinforce each other, and the more stressors an organism is exposed to, the worse its chances of survival. If we can do something to reduce an environmental problem, we should do it. And with light pollution, everyone of us can do something with less effort than to fight against climate change.

„What if we woke up one morning and realize that we missed half of the story in our conservation efforts, namely the night part?”

Catherine Rich & Travis Longcore, Ecological Consequences of Artificial Night Lighting

Earth from space, mostly visible is the day side, there is only a glimpse at the night side with some artificial light from Europe.

If we continue to distroy the night with artificial light, the consequences for the ecology of our planet are incalculable. Sustainable lighting must therefore not only be based on energy consumption, but must also take into account the effects of artificial lighting on local flora, fauna, and microorganisms. Many factors play a role here: the intensity of the light, the direction of the light, the duration of the lighting and the wavelength (light colour and temperature).

There is no such thing as environmentally friendly or neutral light. Instead, we need to fundamentally rethink the use of artificial lighting at night. But where light is really needed, a well-thought-out concept can at least reduce the impact of artificial lighting. And maybe by re-discovering the value of darkness we realise how much energy we’re wasting for light that isn’t needed.

Blogposts about this topic

Light pollution and birds – Part 1: Journey to Death

Green gardening around the clock

Nature- and neighbour-friendly Christmas lights

The LakeLab at Lake Stechlin: Studying the impact of artificial light at night on aquatic ecosystems

Is a 4000 Kelvin LED street light like the moon?

Bats in the spotlight: winners or loosers?