The world is getting brighter — and it's not good news

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 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, said lead author Chris Kyba, a physicist at the German Research Center for Geosciences.

Rather, it's that people keep installing more and more lights, he said.

"We'll light something that we didn't light before, like a bicycle path though a park or a section of highway leading outside of town that in the past wasn't lit," he said.

Study based on VIIRS recordings

The study was based on the first-ever radiometer designed especially for nightlights, called the Visible/Infrared Imager Radiometer Suite (VIIRS).

The VIIRS is mounted on the a National Oceanic and Atmospheric Administration (NOAA) satellite named Suomi NPP, which has been orbiting Earth since October 2011.

Researchers only analysed nighttime lights during the months of October, to avoid any increase from holiday lights.

"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 countries like Syria and Yemen.

"The fact that we did not 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.

Researchers also warned the data was likely an underestimate, because the satellite is unable to pick up the blue wavelengths that are prominent in many LED lights.

Ecological consequences

Excess nighttime 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.

Ecologist Franz Holker of Germany's Leibniz-Institute for Freshwater Ecology and Inland Fisheries (IGB) said that light pollution has ecological consequences, with natural light cycles disrupted by artificial light introduced into the nighttime environment. 

Increased sky glow can affect human sleep, he noted.

"In addition to threatening 30 percent of vertebrates that are nocturnal and over 60 percent of invertebrates that are nocturnal, artificial light also affects plants and microorganisms," Holker said. 

"It threatens biodiversity through changed night habits, such as reproduction or migration patterns, of many different species: insects, amphibians, fish, birds, bats and other animals."