Animals are sorted into categories based on the time of day when they are most active. Animals that are most active during the day are “diurnal”; animals that are most active at dusk and dawn are “crepuscular”; and animals that are most active at night are “nocturnal.” However, as of late, the lines between these categories have been increasingly blurred.
According to multiple studies, to avoid the increasingly high temperatures of the day caused by global warming, diurnal animals are increasingly switching up their behaviors and becoming more active during the night; however, as pointed out in a Scientific American article, these temperature-related behavioral changes have only been studied in the short-term, and the question of whether or not they can signify long-term or even permanent behavior changes is one that requires further research as time goes on to answer. In any case, whether short-term or not, nocturnal activity in diurnal animals can lead to an increased risk of predators and a decreased efficiency foraging and finding food.
Diurnal animals aren’t the only ones struggling due to global warming, either. According to the Environmental Protection Agency (EPA), higher daytime temperatures cause the nights to “cool off” less, resulting in warmer nights as well. In fact, according to a report by Climate Central, summer nights are warming up ever faster than summer days.
On top of dealing with the increasing temperatures largely caused by air pollution, nocturnal animals are also struggling with light pollution. According to the National Institute of Environmental Health Sciences, artificial light can alter the circadian rhythms of animals (that is, a light-sensitive 24-hour cycle an organism’s body goes through behaviorally, physically, and mentally), as well as disrupt many of their natural behaviors. For example, fireflies and glow worms depend on their light for mating and reproduction, and many nocturnal prey animals, such as mice, will avoid artificially lit areas in an attempt to avoid predators, and this can decrease the area available to them for foraging and shelter. Such patterns can be observed even in some of the smallest creatures. According to the National Park Service, zooplankton tend to feed at the deeper, darker depths of the water during the day and at the surface of the water during the night. However, artificial lighting causes them to stay farther down for longer periods of time, hurting aquatic life at higher levels that often feed on them.
On the other end of the spectrum, artificial lighting can also attract animals, especially insects like moths, who often suffer increased predation as a result. Artificial light can also attract nocturnal birds who typically rely on the light of the moon and stars, throwing off their migratory patterns and even causing them to slam into things or circle around, wasting their valuable time and energy. A similar story goes for sea turtle hatchlings who navigate to the sea after hatching by using the reflection of the moon and starlight off the water. Unfortunately, they often end up in streets and parking lots due to the artificial lighting overpowering the natural lighting, leading to their early and untimely demise.
Humans, too, are affected by all this light pollution. Artificial lighting—especially blue light, a form of light emitted by most electronic devices—can mess with a person’s circadian rhythm, reducing the quality of their sleep, ruining their sleep schedule, or both. Light pollution also makes it harder for astronomers to observe celestial bodies.
The worst part is that light pollution isn’t just in directly artificially lit areas. According to the National Park Service, light pollution can be seen up to 200 km (124 miles) away from its source. Furthermore, the Earth is suffering from artificial skyglow, a combination of reflected light and light pointed upwards that causes the sky to brighten, blocking out the stars. Aside from skyglow, there are three other types of light pollution: glare, which is an excessively bright light that can cause visual discomfort and disorientation in both humans and animals; clutter, which is big groupings of artificial light; and light trespassing, which is when light illuminates an area it wasn’t intended to.
While the situation with light pollution may seem rather bleak, there are simple ways that you at home can help. The first and most simple step is to turn off any and all lights that are not in use, especially lights on the outside of the house. If needed, dimmers and motion sensors can help ensure that lights are only on when needed and only as bright as needed. This helps with both global warming and light pollution by reducing energy consumption and avoiding unnecessary illumination. You can also make sure your blinds and/or curtains are shut at night to keep indoor light inside. On a similar note, it helps to make sure all lights face downward and have a shield or cover around them to prevent the light from spreading to places where it’s not needed. The National Park Service also recommends using warm-white or amber lighting instead of blue-white lighting.
To help fight global warming, turn off water and appliances that are not in use. Recycle or even compost where you can. Practicing sustainable shopping and supporting green energy sources also go a long way.
Above all, stay open-minded and learn everything you can about environmental issues. Also, educate your friends, family, peers, and community. Even the most minor actions can make a big difference when many people do them. Education and advocacy go a long way, and there are always organizations to support, movements to join, and petitions to sign.