The magic of christmas lights or… light pollution?

Lights on the roof, on the tree in front of the house, on the garden gazebo. The American fashion of illuminating entire streets is becoming increasingly popular in Poland, and many of us are delighted by these pre-Christmas displays. Unfortunately, there are also side effects – light pollution is the dark side of Christmas celebrations that few people talk about.

A glow over the city, or ALAN

Artificial light at night (ALAN) is one of the greatest landscape changes of the past century. The invention of electricity made it possible to turn dangerous dark streets into brightly lit arteries lined with shops whose displays never go dark. Light pollution in cities has already become so intense that residents find it difficult to see stars in the sky.

Winter and Advent only intensify the scale of this phenomenon. According to NASA, some regions of the Earth are up to 50 percent brighter on December nights than during other months. Neighbours compete in decorating their homes, and shops make a fortune selling glowing reindeer and kilometres of string lights. If snow falls on top of that, the glow becomes even more pronounced, and darkness disappears everywhere and forever.

People celebrate, nature suffers

As we wrote in Wodne Sprawy two years ago, outdoor artificial lighting disrupts natural light cycles that regulate the lives of all organisms on Earth, including humans. It is no coincidence that many flowers close at dusk and animals prefer nocturnal or diurnal lifestyles – these are important survival strategies that underpin balance in ecosystems.

Extensive scientific research clearly shows that light pollution:

• disorients species that move at night, including migratory birds and young sea turtles, which after hatching instinctively follow the brighter horizon of the sea;
• deprives nocturnal animals of protection, exposing them to predator attacks;
• disrupts mating rituals, reducing species fertility;
• disrupts circadian sleep and activity cycles, leading to exhaustion and weakening;
• limits the activity of nocturnal insects, resulting in reduced pollination of some plants.

German studies from 2018 also suggest that light pollution negatively affects the processes governing aquatic ecosystems, disrupting migratory and parental behaviours of many fish species.

The international organisation DarkSky, which campaigns to preserve dark night skies, has already identified more than 5,000 publications on light pollution. Their in-depth analysis shows that ALAN is an increasingly serious threat to biodiversity and at the same time favours the spread of invasive alien species. There is also growing evidence of the negative impact of night-time lighting on the human body, particularly in the context of an increased risk of sleep disorders, depression, retinal degeneration, heart disease and cancer.

How to reduce light pollution during the holidays?

Christmas should be a time of understanding and empathy, not only towards people but also towards our smaller brothers. With this in mind, it is worth radically reducing the number of lights used – let them be symbolic and, most importantly, switched off at night. A lantern with a candle on the veranda is a beautiful tribute to tradition and at the same time a sign of respect for nature.

The Australian group of universities Biodiversity Council encourages choosing more subdued lights and avoiding white and blue LED diodes at all costs, as they are the most disorienting. The placement of illuminated decorations also matters – trees and shrubs should be left to nature, while the focus should be on inanimate elements.