Energy-Efficient LEDs are Escalating Light Pollution

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What’s not to like about LED light bulbs? They use less energy than their incandescent and fluorescent cousins, and last longer. They are projected to save thousands of terawatt-hours of energy in the coming decades, and save users billions of dollars in electricity cost.

But this revolutionary energy-saving technology has a downside. It is increasingly to blame for light pollution, researchers report in the journal Science Advances.

The study shows that artificially lit land area around the world has gone up by 2.2 percent on average every year between 2012 and 2016. This has made our nights brighter by the same amount, which is not good for human or animal health.

We have been losing dark skies since the dawn of electric lights. Light pollution has been linked to disruptions in circadian rhythm, depression, diabetes, and even cancer. It can also meddle with animal migration, reproduction, and species interactions, and interfere with pollination and plant growth patterns.

Researchers from the GFZ German Research Center for Geosciences in Potsdam, Germany, studied images taken each October between 2012 and 2016 by a National Oceanic and Atmospheric Administration satellite. They found stable night brightness in 39 countries that were already bright, including the US and Netherlands.

There was a rapid increase in 59, and an extraordinary increase of over 150 percent in 20 countries. The growth mostly took place in Africa, Asia, and South America.

These increases point to what’s called the “rebound effect” of energy-efficiency technologies, the researchers say. As LED lights have gotten better and cheaper, people and governments are installing more of them, offsetting their energy savings to some extent.

And the reality could be even worse, the researchers say. The sensor used by the satellite instruments cannot detect the blue light emitted by some LEDs that are becoming popular for outdoor lighting.

Choosing light technologies and placement wisely should help solve some of the problem, the researchers say. For example, amber lights are better than white LEDs, and using dimmer, closely placed lamps would decrease light pollution without affecting visibility.

Source: Christopher C. M. Kyba et al. Artificially lit surface of Earth at night increasing in radiance and extent. Science Advances. 2017. 

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