Zoologist Johan Eklöf began considering the disappearance of darkness in our brightly lit world in 2015, when he was counting bats in southern Sweden. The surrounding grounds were dark, as they had been decades before when his academic adviser had counted the bat populations in the region’s churches. However, in the years since then, those churches had been illuminated with floodlights. “I started thinking, how do bats really react to this?” Eklöf said.
The short answer: not very well. With his adviser, Jens Rydell, Eklöf launched a new bat census and found that in 30 years—the average lifespan of a bat—half of the area’s colonies had disappeared.
That research soon led Eklöf to investigate how artificial lighting affects other species—including the species responsible for installing floodlights in churchyards. The resulting book, “The Darkness Manifesto,” published in Swedish in 2020 and in English last month, is a far-reaching exploration of humanity’s troubled relationship with the dark and the damaging effects of our drive to overcome it.
Astronomers began using the term “light pollution” in the 1960s, and today it most often refers to the lingering glow emanating from cities after dark. By 2016, 80 percent of the world’s population—and 99 percent of the population in the US and Europe—lived under light-polluted skies.
Earlier this year, a study published in the journal Science found that between 2011 and 2022, light pollution on Earth increased 9.6 percent annually. “I had been pretty optimistic that with the newer technology things would get better, because the lights are better designed. But instead, what we saw is that most countries are getting brighter,” Christopher Kyba, a researcher at the German Research Center for Geosciences and lead author of the study, said of the results.
Today, a third of the world’s population cannot see the Milky Way, even on the clearest night. But the impact of all that light goes beyond the impediment of stargazing. As “The Manifesto of Darkness” explains in detail, all living organisms are governed by light-sensitive circadian rhythms that, if disrupted, can trigger effects ranging from an impaired sense of direction to mass deaths (this is how the swarm ended of grasshoppers that, attracted by a lightning strike from the Luxor casino, descended on Las Vegas in 2019, only to end up as a lifeless pile of confetti filling the Strip).
But it’s not just insects. Newly hatched sea turtles head inland toward the glow of the city instead of the moonlit sea. On one Australian island, the light was so disturbing that kangaroos, whose gestation normally begins at the summer solstice, ended up giving birth so late in the season that food had run out.
Even coral, which in Australia normally reproduces once a year when the December full moon prompts it to release a “blizzard” of male and female sex cells, is getting confused; disoriented by artificial light, the release of gametes is no longer synchronized, slowing reproduction and contributing, it is believed, to coral bleaching.
Eklöf also found that light pollution has increased insomnia, depression, and even obesity in humans.
Some places are taking action. France has adopted a national policy imposing curfews on outdoor lighting. And some countries are embracing “dark sky tourism,” which encompasses activities like stargazing hikes or excursions to see the Northern Lights.
By: Lisa Abend
BBC-NEWS-SRC: http://www.nytsyn.com/subscribed/stories/6599240, IMPORTING DATE: 2023-03-06 22:00:07
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