By Heather Hamilton, contributing writer
The total acreage lit by artificial light at night has increased by about 2.2% per year and the brightness of the areas lit has risen at the same pace, according to new data. The findings are contrary to what others predicted after the introduction of efficient LEDS, which have instead encouraged people to use more light.
The GFZ German Research Center for Geoscience looked at data collected between 2012 and 2016, ultimately finding that the use of light at night increased in brightness globally — across most of Africa, Asia, and South America. In countries where light was already bright (like the Netherlands and the United States), brightness remained stable but didn’t decrease.
Light pollution has long been an issue for both astronomers and city-dwellers. Artificial lights affect the natural environment, including living creatures, but also create unpleasant glare in windows. According to Forbes , approximately 30% of vertebrates and 60% of invertebrates are nocturnal, meaning that artificial light significantly impacts their wellbeing, leading to decreased sleep, problems hunting (and, therefore, eating), etc. Plants are also affected, altering insect populations, which leads to changes in pollination and growth periods.
In humans, light pollution can decrease the production of melatonin in the body, which provides for sleep, better immune systems, and even lower cholesterol. And, from a non-medical perspective, it interferes with our ability to view stars and other celestial objects.
Because the satellite data is collected by a sensor incapable of detecting blue light, the researchers say that these numbers are likely understated. IEEE Spectrum explains that LED street lamps contain blue LEDs, which excite yellow phosphors to produce a blend of colors that, to the human eye, look white. These lamps can block blue, though blue-rich LEDs are preferred because they work more easily with human night vision. Approximately half the output from an LED lamp can be missed by the sensor.
Christopher Kyba, a member of the GFZ German Research Center for Geoscience, says that, because the sensor cannot detect blue light, cities like Milan that have transitioned to LEDs recorded a decrease in light. To accurately explore changes in brightness, researchers will have to use a sensor that can accurately record brightness across the visible spectrum.
“Regardless of historical or geographical context, humans tend to use as much artificial light as they can buy for about .7% of [gross domestic product],” says the report. So, while we could be saving money via higher efficiency lights, we’re instead turning on more.
Sources: Science Advances, Forbes, IEEE Spectrum
Image Source: Pixabay
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