They were supposed to bring about an energy revolution - but the popularity of LED lights is driving an increase in light pollution worldwide, with dire consequences for human and animal health, researchers said on Wednesday. The study published in the journal 'science advances', is based on satellite data showing that the Earth's night is getting brighter, and artificially lit outdoor surfaces grew at a pace of 2.2 percent per year from 2012 to 2016. Experts say that's a problem because nighttime lights are known to disrupt our body clocks and raise the risks of cancer, diabetes and depression. As for animals, these lights can kill - whether by attracting insects or disorienting migrating birds or sea turtles. The issue isn't just the LED lights themselves, which are more efficient because they need far less electricity to provide the same amount of light, explained lead author Chris Kyba, a physicist at the German Research Centre for Geosciences. Rather, it's that people keep installing more and more lights, he told reporters on a conference call to discuss the research.
"And so all of those new uses of light offset, to some extent, the savings that you had". Experts call this the 'rebound effect', and it can be seen with fuel-efficient cars, too. People may buy a car that requires less fuel, then decide to drive it more often or move further from work, lengthening their commute. The study was based on the first-ever radiometer designed especially for night-lights, called the Visible/Infrared Imager Radiometer Suite (VIIRS). The VIIRS is mounted on the National Oceanic and Atmospheric Administration (NOAA) satellite named Suomi NPP, which has been orbiting Earth since October 2011. Researchers only analysed night-time lights during October, to avoid any increase from lights during the Christmas season. "With few exceptions, growth in lighting occurred throughout South America, Africa and Asia", said the report.
Declines in lighting were rare, but were noticeable in war-torn places like Syria and Yemen. Some of the world's brightest areas, including Italy. Netherlands, Spain and the United States, were all relatively stable. But even though Milan, for example, made the switch to LED lights and saw a drop in radiance over the 2012-2016 period, there were increases elsewhere in Italy. "The fact that we didn't see the country get darker means that there were new lights in other places, or else brighter lights that were in some other cities installed that make up for this difference", said Kyba. Excesses night-time light not only harms natural habitats and makes stargazing impossible, it also costs nearly seven billion dollars annually in 'negative impacts on wildlife, health, astronomy, and wasted energy", according to a 2010 study in the journal Ecological Economics. Experts say solutions include turning lights off when people leave an area, and choosing LED lights that are amber instead of blue or violet, since these tend to be the most harmful to animals and humans.
-Challapalli Srinivas Chakravarthy-
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