Rise in energy-saving LED lighting has increased light pollution

Rise in energy-saving LED lighting has increased light pollution

According to the paper in Science Advances, the artificially lit surface of Earth at night increased in radiance and extent over the past four years by 2 per cent annually. A study published Wednesday in the journal Science Advances, finds the Earth's artificially lit outdoor areas grew by 2.2 percent per year from 2012 to 2016.

The biological impact from surging artificial light is also significant, according to the researchers.

"I was very surprised by the result of the study, particularly in wealthy well-lit countries like the USA", said Christopher Kyba of the GFZ German Research Centre for Geosciences, lead author of the study. Their measurements coincide with the outdoor switch to energy-efficient and cost-saving light-emitting diodes, or LEDs.

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. The findings shatter the long-held notion that more energy efficient lighting would decrease usage on the global - or at least a national - scale.

However, not all satellites can detect blue light generated by some LEDs, which makes the scientists believe light pollution is far worse than thought. People's sleep can be marred, in turn affecting their health.

Plants can have abnormally extended growing periods when exposed to the glare of artificial light, they add. And forget about seeing stars or the Milky Way, if the trend continues.

Researchers used a device specially designed by Nasa to measure the brightness of night-time light.

The study also noted a consistent growth in lighting in South America, Africa and Asia, with a few exceptions in regions like Yemen and Syria, which showed a decrease due to escalating conflict and warfare.

Only a few countries showed a decrease in brightness, such as Yemen and Syria - both countries now experiencing hard wars.

The improved energy efficiency has therefore led to more LED lighting being installed in households and outdoors, Kyba said. People may buy a vehicle that requires less fuel, then decide to drive it more often or move further from work, lengthening their commute.

Image Carla Schaffer  AAAS
Image Carla Schaffer AAAS

Other especially bright hot spots: sprawling greenhouses in the Netherlands and elsewhere.

Photograph of Calgary, Alberta, Canada, taken from the International Space Station on November 27, 2015.

Scientists say that this is resulting in a "loss of night" in many countries.

"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.

One co-author of the study, Franz Holker, an ecologist at the Leibniz Institute for Freshwater Ecology and Fisheries, said the data reveal "quite a critical problem".

"Not just the economic cost, but also the cost that you have to pay from an ecological, environmental perspective". For example, dim, closely spaced lights tend to provide better visibility than bright lights that are more spread out. This was linked to increased brightness at nighttime, as the body expects light during daytime and darkness at night.

This can have negative consequences for animals, people and plant-life.

An instrument on the 2011-launched US weather satellite, Suomi, provided the observations for this study.

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. This latest VIIRS will join the continuing night light study.