Human Activities Shine A Dark Light On Nature

Light pollution, caused by the inefficient or unnecessary use of artificial light, is a pressing issue that has gained little attention compared to other forms of pollution. It is a human-made phenomenon, resulting from the excessive use of artificial light at night, which spills into the natural world. Light pollution has detrimental impacts on human health, wildlife behaviour, and our ability to observe the night sky. It can also lead to economic losses and negatively affect ecosystems. With growing awareness, there is a global movement to address light pollution and mitigate its adverse effects.

Poor lighting design

There are several ways in which poor lighting design can lead to this form of light pollution. Firstly, outdated lighting systems and fixtures that cast light in all directions without proper shielding or controls can result in excessive light spillage. This not only wastes energy but also contributes to sky glow, as the light reflects off particles in the atmosphere. In addition, the absence of light shields or controls can result in light trespass, where light beams unintentionally trespass into adjacent properties, disrupting the sleep and circadian rhythms of occupants.

Another example of poor lighting design is the use of cobra-head streetlights, which emit about 30% of their light directly upwards. The use of flat-lens cobra luminaires, which are full-cutoff fixtures, can help mitigate this issue by directing light only below the horizontal plane, reducing light waste. However, in roadway installations, full-cutoff fixtures may not always be the best solution, as they can result in over-illumination or poor uniformity, potentially causing glare and affecting driver safety.

The consequences of poor lighting design extend beyond environmental concerns. Excessive or poorly managed lighting can lead to increased energy consumption and higher operational costs for businesses. It can also impact human health, causing sleep deprivation, fatigue, headaches, stress, anxiety, and potentially more severe health issues. Additionally, poor lighting design can affect wildlife behaviour, disrupting migration patterns, wake-sleep habits, and habitat formation.

Blue light from devices

Blue light is part of the natural electromagnetic energy spectrum, and most of our exposure to blue light comes from the sun. However, with the proliferation of electronic devices, humans are increasingly exposed to artificial blue light, particularly at night. This artificial blue light comes from digital screens and light-emitting diodes (LEDs), which are popular in homes and cities due to their low cost and energy efficiency.

To mitigate the negative impacts of blue light from devices, several measures can be taken. Reducing screen time and taking frequent breaks from electronic devices is advisable, especially before bedtime. Additionally, blue-light-blocking glasses or apps that filter blue/green wavelengths can be used to minimize exposure, and switching to amber-light mode on devices can help reduce blue light intake.

While blue light from devices can have adverse effects, it's important to note that blue light exposure during the day can have some benefits. Blue wavelengths boost attention, reaction times, and mood, so exposure to blue light during daylight hours can be advantageous.

Over-illumination

The excessive use of artificial lighting can have negative consequences for both humans and wildlife. From a human health perspective, there is growing concern about the impact of increased artificial light exposure, particularly at night. Studies have linked artificial light at night to various adverse health effects, including sleep deprivation, fatigue, headaches, medically defined stress, decreased sexual function, and increased anxiety. Shift work and night work have also been associated with an increased risk of certain cancers, although more research is needed to establish a direct causal relationship.

For wildlife, the disruption caused by over-illumination can be detrimental. Many animals rely on natural light cues from the sun, moon, and stars to establish migratory patterns, sleep habits, mating rituals, and hunting techniques. When these light cycles are disturbed by excessive artificial light, it can have disastrous consequences. For example, sea turtles, which instinctively move towards the brightest light, can become disoriented and crawl towards coastal cities instead of the ocean, leading to dehydration, predation, and death. Similarly, birds and insects are attracted to artificial lights, resulting in fatal collisions with buildings or other structures.

To address the issue of over-illumination, it is essential to adopt a thoughtful approach to lighting installations. This involves using light only when necessary, directing it to specific areas, and ensuring it is no brighter than required. By minimizing unnecessary lighting and reducing light spillage into the sky, we can not only conserve energy and reduce costs but also mitigate the harmful effects of over-illumination on both human health and wildlife behaviour.

Light trespass

To address light trespass, it is recommended to first communicate with the neighbour responsible for the offending light source. It is possible that they are unaware that their lighting is causing a problem, and a cooperative solution can be found. DarkSky International provides a sample letter to help initiate this conversation constructively.

In the United States, several cities have developed standards for outdoor lighting to protect citizens' rights against light trespass. The International Dark-Sky Association has also created model lighting ordinances to reduce light pollution. These standards include limiting light emissions above 90 degrees from the nadir, which has been effective in reducing light trespass issues occurring in the 80-90 degree range.

Impact on wildlife

Light pollution, caused by the excessive or inappropriate use of outdoor artificial light, has a significant impact on wildlife behaviour and ecosystems. It radically alters the nighttime environment, disrupting the natural rhythm of day and night that life on Earth has relied on for billions of years.

One of the most well-studied impacts of light pollution is on sea turtles. Sea turtle hatchlings instinctively move towards the brightest light source, which, for centuries, was starlight reflecting off the ocean. However, with coastal cities illuminating the night sky, the hatchlings become disoriented, heading towards the cities instead of the sea. This confusion leads to increased predation, dehydration, and mortality, with hundreds of thousands of hatching losses in Florida alone each year.

Birds are also significantly affected by light pollution. They become disoriented by lights, resulting in higher mortality rates due to collisions with artificial structures. Migratory birds may abandon preferred roosting sites to avoid lights, and their migration patterns can be disrupted by artificial light, causing them to lose their way. Additionally, light pollution can impact bird reproduction. A study on a North American songbird species found that artificial light at night accelerated the seasonal relapse of haemosporidian parasites, which are known to cause avian malaria.

Light pollution also influences insect behaviour and populations. Insects are drawn to artificial lights, leading to their instant death upon contact. It affects their movement, foraging, reproduction, and predation. As insects are a primary food source for birds and other animals, the decline in insect populations due to light pollution can have cascading effects on the food web.

Furthermore, light pollution can disrupt nocturnal animal behaviour. Predators use light to hunt, while prey species rely on darkness for cover. The introduction of artificial light represents a drastic change to the nocturnal environment, impacting the activities of both predators and prey.

Overall, light pollution has far-reaching consequences for wildlife, affecting their migration, reproduction, hunting, and feeding behaviours. It disrupts the natural cycles that wildlife depends on, threatening the delicate balance of ecosystems.

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