In 2014, Los Angeles reduced annual carbon emissions by 43% and saved $9 million in energy costs by replacing the bulbs in more than half of city street lights with LEDs.
That year, the Nobel Prize in Physics was awarded to three scientists whose work made those lamps possible. When announcing the award, the Nobel Committee explained: “Since a quarter of the world’s electricity consumption is used for lighting purposes, LED lights contribute to saving Earth’s resources.”
For more than a century, most artificial light sources have been wasting energy in the form of heat. LED lights are more efficient, requiring 25% less energy than an incandescent bulb. By 2020, LED lights made up 51% of global lighting sales, up from just 1% in 2010, according to the International Energy Agency, an intergovernmental organization that analyzes global energy data.
Seems like a clear win for the environment. But that’s not how Ruskin Hartley sees it.
“The impetus for the efficient formulations came at the expense of the rapid increase in light pollution,” he said.
Hartley will know. He is the CEO of International Dark-Sky Assn. , or IDA, is one of a growing number of people who say the dark sky is an undervalued natural resource. Its loss has adverse consequences for wildlife and human health.
However, the public’s embrace of LED lights continues to rise, spilling so much light into the sky where no one needs it.
“We saved a lot of energy and lit additional places,” Hartley said. It is a classic example of the Jevons Paradox, where efficiency gains (such as increased fuel consumption in cars) are counteracted by increased consumption (people who drive more often).
In essence, we’ve replaced one type of pollution with another, Hartley et al. say.
This is not the only problem. In addition to making more light, LEDs have changed their basic nature.
The light from incandescent bulbs had warmer yellow or amber hues, “more in tune with the light of fire, which is the only light other than starlight that we know of,” said Robert Meadows, a scientist with the National Park Service’s Department of Natural Sounds and Night Sky. LEDs, by contrast, give off cooler bluish-white tones that exacerbate light pollution for the same reason that the sky is blue.
Sunlight has a full spectrum of colors, and air molecules happen to be just the right size to scatter the shorter blue wavelengths more effectively than any other particles. This causes blue light to spread more easily in the atmosphere, giving the daytime sky its familiar color.
After sunset, the same thing happens with LED light that is lavishly poured into the sky: it spreads out further and increases the “sky glow,” the combined radiation of city lights.
Travis Longcore, an urban ecologist at UCLA, estimates that artificial lighting makes the Los Angeles night sky one and a half times brighter than a full moon night. All creatures are affected by the brighter night scenes, especially those who cannot close the curtains to get a deep sleep.
“There are lots and lots of species that don’t go out foraging during the full moon because they are so bright and they know they will be vulnerable to predators,” he said.
According to the National Audubon Society, 80% of migratory bird species in North America fly at night, confused by city lights.
Even species that remain in place are forced to move their homes. A recent study led by Longcore found that western snow plovers, an endangered species of shorebird, seek safe spots in dark areas of Santa Monica Bay when empty parking lots are lit up by floodlights all night.
The survival of wild species depends on the diversity of the natural world – day and night, seasons, the lunar cycle. Take them away, said Longcore, and you will inevitably begin to drive the species out of their natural habitats.
Snakes, for example, are most active and hunt prey during new moon nights. The disappearance of the California bright python and the long-nosed python from Orange County is largely due to increased ambient lighting.
Humans are also susceptible to light pollution. Artificial light blocks the production of melatonin, a hormone that regulates sleep cycles, and disrupted sleep cycles have been linked to a host of health issues. American Medical Foundation. He warned in 2016 that high-intensity, rich blue LEDs were associated with poorer sleep times, dissatisfaction with sleep quality, excessive sleepiness, poor daytime performance, and obesity.
Longcore calls it a “historic coincidence” that the first LEDs that became readily available were blue and white. LED lights that produce warmer colors are now available at similar levels of efficiency, but the original remains popular with consumers who prefer the way it mimics daylight.
Because of the glare of the sky, light pollution is not just a local phenomenon. Even areas hundreds of miles from urban centers cannot escape them.
“You can see Los Angeles from Death Valley at night,” Meadows said.
The reason light pollution is steadily getting worse, Hartley said, is that people don’t even realize it’s a problem.
“I don’t think anyone intentionally intends to pollute the night,” he said. But when it comes to lighting our surroundings for safety, “there is an assumption that because less light is good, more light should be better.”
The only good thing about light pollution is that, unlike pollution from chemicals or plastics, it is completely reversible. Just turn off enough lights and the dark sky will be back in an instant.
“The solution is not to plunge us into medieval darkness,” Hartley said. It involves carefully thinking about the purpose of each fixture installed, making sure the light is limited to its allotted space, and only turning on for the required time.
Mexico, France and Croatia have enacted national laws on light pollution. Since 2013, France has required all shops and offices to turn off the lights after 1 a.m.
Nineteen states, the District of Columbia, and Puerto Rico have laws on the books to prevent light pollution. Arizona, home to many large telescopes, requires all outdoor lights to be fitted with shields that prevent light from escaping toward the sky. Some coastal areas of Florida mandate low-power amber lights that do not attract baby sea turtles away from the safety of the Gulf of Mexico.
There are no such laws in California, but Assemblyman Alex Lee (De San Jose) introduced a bill that would require all exterior lights in state government buildings to be shielded and have warmer hues. They will also need to be dimmed or turned off at night, although they can be turned on if they are activated by the motion sensor.
The bill passed both houses of the legislature, and it is now up to Governor Gavin Newsom to decide whether to sign it.
Being restricted to state property, the bill does not address the worst offenders in light pollution, which include stadium floodlights, industrial lights, outdoor residential lights and street lights.
However, Longcore sees it as a “small step to take”. If the government leads by example, he said, more people will realize the importance of the issue.