Big History





Roger Mira

At the beginning of 2023, the prestigious scientific journal “Science” published a study concluding that light pollution is growing at a rate of almost 10% per year, which is beginning to be seen by society as an alarming problem.

Variation of light pollution in the east of the Iberian Peninsula and the Balearic Islands from 1996 to 2006

Although it may seem that the problem with night-time lighting is new, nothing could be further from the truth: back in the 1980s, astronomers were the first scientists to raise the alarm about the loss of darkness in the sky, with the difficulties it caused them in observing the faint light of objects thousands or millions of light years away, due to the increasingly noticeable overlighting of large cities.

Insects trapped by the lights of a sports facility in Girona

Although astronomers were the first to become aware, they were not the only group of scientists to warn of the problem: biologists discovered that uncontrolled artificial light also affects ecosystems, causing serious alterations to nocturnal fauna; perhaps the most affected are insects, which suffer a fatal and irresistible attraction to artificial lights, migrating from rural areas to urban centres and becoming trapped fluttering around streetlights until they perish from exhaustion. When the insects disappear, all the animals that feed on them also disappear. In other cases, nocturnal hunters cannot carry out their usual strategies to capture their prey because, in an excessively illuminated environment, the surprise factor disappears, leading to the proliferation of pests such as rodents, among others.

Strongly overlit night sky in the València metropolitan area

It is estimated that, because of artificial lighting, the Earth’s atmosphere is almost 100 times brighter than it was 100 years ago. For many animals, this is a serious problem. Many migratory birds make their annual journeys at night and are severely affected by the excessive lighting in metropolitan areas, causing severe disorientation and, in the worst cases, death.

The marine environment is also not spared from the effects of excessive light at night: as has been seen in Galicia, marine areas affected by artificial lighting from land are running out of fish, as these animals, lacking eyelids, cannot defend themselves at night against excessive light and cannot survive in over-lit waters, with the consequent economic disadvantage for the mariñeiros.

Life on our planet has been adapted for millions of years to a natural pattern of daylight and darkness at night following the 24-hour circadian cycle. We have given a few examples of what happens when we artificially alter this natural cycle by introducing artificial light night after night, but we could go on for much longer.

Over-lighting of the coastline in the Marina area

We may think that this is an inevitable effect of the need to light our streets in order to be able to travel them safely, but we will shortly explain that this reasoning is false, as the light that escapes from our cities and towns is largely due to poorly designed lighting systems, wasting enormous amounts of money from the public purse.

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