"Somewhere else, there's new light".
The American Medical Association a year ago said that white LED lights are increasingly suspected of impacting humans, estimating they have "five times greater impact on circadian sleep rhythms than conventional street lamps".
The team expected to see a decrease in brightness in wealthy areas like the UK, US and Germany where energy-efficient LEDs had been rolled out, because the bluer light they emit can not be picked up by the satellite's light sensor. "This is concerning because artificial light is an environmental pollutant". "What happens instead is that people put more lights up". It's also a problem for nocturnal animals, plants, and microorganisms.
"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", he said. "Seeing the big picture from above, completely changed how I use light at night". That's why working against our biological day-night clocks (for example, as night-shift workers must) can result in many kinds of issues, from depression-like symptoms to obesity and diabetes.
A team of worldwide researchers has found that, despite an increase in energy-efficient LED bulbs, surface light pollution has increased around the world. The research was led by Christopher Kyba of the GFZ German Research Center for Geosciences and other colleagues.
The goal was to track and map night illumination around the planet from 2012 to 2016 - a job was a lot more complicated than simply staring at the ground and noting which square miles are lit at night and which are dark. "And you see things like the bridge in Montreal", Kyba said.
The observed "decrease" in Western Australia is actually due to wildfires in 2012 that were visible from space. Then too there is scattered light.
"In the longer term, perhaps the demand for dark skies and unlit bedrooms will begin to outweigh the demand for light in wealthy countries", the team of authors wrote.
The ever-widening use of artificial lights is making the nighttime Earth glow increasingly brighter, with the amount of global light growing about 2 percent each year.
KYBA: And we saw an increase of an average of about 2.2 percent per year, which is pretty close to 10 percent over the study period. Overall radiance, or the brightness of all of the lighting combined, grew by 1.8 per cent annually. Turning off lights while leaving an area might also be a contributing factor. A growth in a region's gross domestic product of 13 per cent over the course of the observation period was reflected in a almost matching 15 per cent increase in night lighting.
"There is a potential for this lighting revolution to save energy and reduce light pollution - but only if we don't spend the savings on new light", he added.
And nature is paying a price. The effects are largely unknown, but one recent study found that low intensity light reduced the population of pea aphids by preventing flowering in one of their key sources of food. Rather than being content with the savings made, it appears that there has been a "rebound" effect, in which many towns chose to install even more lights as a result, precisely because of these savings.
NELL GREENFIELDBOYCE, BYLINE: Light pollution can keep people from seeing the stars.