‘Darkening’ cities is as important for wildlife as greening them

For billions of years, life has depended on Earth’s rhythm of day and night. DNA codifies body clocks in all animals and plants, which helps their cells act according to this cycle of light and dark. Humans have disrupted this cycle, though, by producing artificial light at night. A growing body of scientific evidence shows this can have negative effects on many different forms of life.

Essentially, artificial light at night changes the sensory capacities of living things. It can disturb the magnetic orientation of migratory birds and beguile insects, causing them to become easier prey and exhausting them. The same disruption to body clocks we see in wildlife is also linked to health consequences in people.

Apart from some caves, deserts and deep-sea trenches, most of Earth has been invaded by light pollution to some degree, or is under threat of its encroachment. In 2001, astronomer Pierantonio Cinzano and colleagues created the first global atlas of light pollution. It calculated that two-thirds of the world’s population lived in areas where nights were at least 10% brighter than natural darkness.

Source: ECEEE