Light Pollution Blocks the Night Sky for One-Third of Humanity
Sixteenth-century philosopher Francis Bacon once wrote, “In order for the light to shine so brightly, the darkness must also be present.”
Boy, things have changed since then. Now the world shines so brightly the darkness has been all but wiped out in many places, with consequences to our health as well as our appreciation of the stars.
That’s the not-so-bright news from a new study, published Friday in Science Advances, which found that artificial lighting has become so ubiquitous and powerful that one-third of humanity—including nearly 80 percent of Americans and 60 percent of Europeans—can’t see the stars in the night sky anymore.
More broadly, the researchers found that more than 6.1 billion people—83 percent of the world’s population—live with some level of light pollution on a nightly basis.
The research, which has been called an atlas of the world’s light pollution, collected cutting-edge satellite imagery and thousands of ground observations to dramatically illustrate how much brighter the world has become over the past 20 to 30 years.
“It is always surprising how in a few decades of lighting growth we enveloped most of us in a light curtain that hides the view of the greatest wonder of nature: the universe itself,” said Fabio Falchi of the Light Pollution Science and Technology Institute in Thiene, Italy, who led the study. “This is a huge cultural loss with unforeseeable consequences in the future generations.”
Beyond the cultural value, light pollution also can affect human health by disrupting our natural circadian rhythm and melatonin production, which can lead to suppressed immune function and sleep disorders and contribute to depression, obesity, and diabetes. Some studies have even linked light pollution to the occurrence of breast cancer.
Artificial lighting also disrupts the natural cycles of all wildlife, from mammals to birds to sea turtles to insects. One of the most recent studies about this effect, published earlier in June, linked artificial lighting to decreased pollination by moths. That research found that energy-efficient LED lighting has made things worse in some cases because many of the lights operate at frequencies that can be more harmful to humans or wildlife.
Falchi said this is worrying because past increases in lighting efficiency resulted in more use of artificial nighttime lighting. “This time, if not regulated, the transition toward LED lighting will give the same result,” he explained.
That doesn’t mean LEDs should be abandoned. “I think LEDs have the potential to greatly reduce light pollution and make our cities more pleasant at night, but that potential is currently in many cases being wasted,” said study coauthor Christopher Kyba of GFZ German Research Centre for Geosciences in Potsdam, Germany. “I think a lot of local governments have rushed the transition to LEDs without adequately considering issues of aesthetics and environmental impact beyond electricity savings.”
Falchi said that he and his colleagues hope the paper will serve as an alarm and set in motion ways to alleviate light pollution. “The first step is to raise the awareness to the problem,” he said.
Data from the paper may be helpful in creating solutions. The atlas will be made available for use on the Google Earth mapping system, so researchers will be able to use the information to study where lighting problems exist and how they may affect people and wildlife. Travis Longcore, science director of The Urban Wildlands Group, who was not involved with the study, said he hopes to combine the atlas with additional on-the-ground observations “to describe the conditions experienced by wildlife in a habitat that might not be measured from space.”
Although the problem of light pollution has gotten worse, Kyba hopes for change. “I think that more and more members of the lighting industry and local and national governments are taking light pollution seriously and including it in decision-making processes,” he said. “I would like to see that trend continue and expand.”
He also suggested a way that anyone could benefit from the atlas. “I think most people will use the interactive map to look at different locations, compare them, and especially look for places near to them where they can go to stargaze,” he said.
That’s a bright idea, indeed.