When Nights Turn Into Days: Increasing Light Pollution
Light pollution became so powerful that our planet started losing its darkness and nights are shinning almost as bright as days. Specialists developed a new study using satellite information. They have revealed that the number of artificially lit areas around the globe gradually increases, generating more light pollution at night.
The new study was described in the journal Science Advances, revealing the worrisome trend unveiled by scientists. Light pollution constitutes a severe problem for the environment and also for human health. Franz Holker is one of the study authors, being a scientist at the Leibniz-Institute of Freshwater Ecology and Inland Fisheries. He indicates that light pollution is a great concern.
Artificial light is considered an environmental pollutant. It has evolutionary and ecological implications for several species, ranging from bacteria to mammals. Artificial light can alter whole social, ecologic systems. Due to the use of electric lights, on the second half of the 20th century, the rate of outdoor lightning increased by 3-6% on an annual basis.
It is true that artificial light is a great benefit when it comes to human safety and productivity. However, it also has its disadvantages. The night is no longer as dark as it used to be. Specialists indicate that a quarter of North America and half of Europe are very bright, as seen from space. They experience severely altered light-dark cycles.
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Light pollution affects many plants and animal species
Scientists call this phenomenon “the loss of night”. Light pollution might severely influence living creatures, including humans. Many species have evolved due to the existence of a certain natural day-night cycle. In the past, the major sources of light during the night was the moon, volcanoes, auroras, and lightning.
Holker highlights the fact that artificial light during the night can be a great stressor if we were to look at this problem from an evolutionary perspective. The main issue regarding light is that people introduce it now at times, intensities and places where it does not naturally occur. The tragic part here is that numerous organisms are still unable to adapt to this kind of stressor.
Over 60% of the invertebrates and 30% of vertebrates are nocturnal creatures, and this could be a really big issue for them. Light pollution can affect microbes and numerous species of plants. Scientists also underline the fact that many vital interactions among species could be disturbed because of the abundance of light during the night.
For instance, nocturnal pollinators may find it more difficult to spread the seeds or pollinate the plants. All that light could prevent them from getting out there in the night. The increase of light pollution represents a threat to biodiversity, modifying night habits. Many species could have their migration and reproduction patterns impaired due to light pollution. Hence, this change forces several organisms, like bats, birds, fish, amphibians, and insects to change their habits.
New study shows light pollution gradually increasing
Believe it or not, the increase in artificial light use can also impact humans’ health. We are used to the fact that there are particular physiological processes which occur during the day and different ones which happen at night. Generally, these processes work against each other. Specialists explain that humans can suffer from many issues if working against their biological day-night clocks. The list of problems can include depression-like symptoms of diabetes and obesity.
Furthermore, the use of artificial light in massive amounts also affects astronomers. They are no longer able to see the stars properly when the night sky becomes brighter. Hence, they find it difficult to analyze the sky, stars, and planets using ground-based telescopes.
An international team of researchers decided to use the Visible Infrared Imagining Radiometer Suite (VIIRS) to reveal if the human demand for light is still increasing. The satellite sensor represents a collaboration between the National Oceanic and Atmospheric Administration and NASA. Scientists have studied the information registered by the satellite staring from the year 2012 to 2016.
The study revealed that during this time span, Earth’s artificially lit outdoor surface increased by 2.2% every year. Furthermore, the total radiance has also increased by 1.8% every year. The outdoor areas which had been lit when the study started in 2012 also became brighter by 2.2% on an annual basis. The fastest growth was more visible in developing countries from South America, Africa, and Asia.
The night turns into day
On the other hand, the countries that were already heavily polluted by light, like Spain and the U.S., appeared as stable. However, some of the countries which experienced wars indicated a decrease in the use of artificial light. Syria and Yemen are two of them. Scientists underline the fact that even if for some countries the levels of artificial light remained steady, there are chances for them to rise.
Experts explain that numerous brightly lit cities around the world have started replacing yellow-orange sodium lights with energy-saving LED lights. The sodium lights appear to put out a diminished amount of infrared radiation. Hence, this would have made them look even brighter to the satellite.
On the other hand, the white-toned lights emit more blue wavelengths, and VIIRS cannot perceive them. This means that VIIRS does no longer register infrared lights because they have been replaced with blue wavelengths. What is more, the satellite is unable to spot blue wavelengths. Therefore, it will perceive these areas as being dimmer than the rest, even if they might be brighter since they use LED lights.
Christopher Kyba is the lead author of the study, being a scientist at the German Research Center for Geosciences. He indicates that the measurement they report only represents a lower bound on how Earth’s light can increase. However, the true increase we perceive is even larger than what the satellite reports. The use of LED lights is to make lightning more efficient, saving more energy. However, people tend now to put them everywhere.
Light pollution clearly does not compare with other types of pollution on Earth, like water pollution or air pollution. However, we need to keep in mind that this also impairs animals’ cycles and affect the environment. Many plants and animal species are unable to adapt. The increase in light pollution also affects humans and our day-night cycle. Even if our future should be brighter, no one had light pollution in mind when saying that.