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Experts Say Light Pollution Is Making the Night Sky Brighter

Light pollution is apparent in most cities, but now, the night sky is getting brighter. Here's everything you need to know.

Written by
Angelica Pizza

Big cities like New York City are no stranger to light pollution. After all, New York is the city that never sleeps. However, now more than ever, metropolitan areas across the globe—from Singapore to London to San Francisco—are experiencing a major increase in light pollution. One that's making the night sky appear brighter.

On April 19, 2022, Michael Marlin, a dark sky ambassador for the International Astronomical Union and a delegate of the International Dark-Sky Association, presented his findings on the impact of light pollution to the Hawai‘i County Council's Committee on Climate Resilience and Natural Resource Management.

In his presentation, “Dark Skies in Hawai‘i: A Natural Resource Worth Protecting,” Marlin noted that Hawai‘i is also losing its night sky to increased light pollution. And protecting the dark sky is crucial to protecting nocturnal wildlife and reducing greenhouse gas emissions.

According to a 2016 study, more than 80% of the world is living under light-polluted skies—including 99% of U.S. and European populations. And this abundance of light pollution correlates to increases in urbanization, population, and development.

The Social and Environmental Impact of Light Pollution

According to Marlin's findings, 2,500 stars should be visible in the sky on a clear, dark night. However, in "moderately illuminated suburban areas," only about 300 stars are observable. And now, Hawaiian islands like Oahu are experiencing an increase in light pollution, impacting dark skies. Thus, impacting ecosystems, public health, and even the economy.

And Marlin isn't the only one to draw these conclusions. According to National Geographic, light pollution—or the excessive use of outdoor artificial light—is a "global issue" impacting human health, wildlife behavior, and the ability to observe stars and celestial objects.

In terms of human health, excessive light can confuse our sleep cycles, lowering melatonin levels and increasing sleep deprivation, depression, anxiety, stress levels, and more. Plus, according to Marlin's presentation, it can also correlate to diabetes, obesity, eye damage, and heart disease.

In addition, keeping cities lit up around the clock confuses wildlife behaviors such as impacting sleep and migration patterns. For example, many bird species are particularly impacted by bright nights. The bright lights prevent some birds from being able to migrate at night, guiding them in the wrong direction or confusing seasonal schedules.

In Marlin's presentation, he notes the different forms of light pollution: glare, clutter, sky glow, over-lighting, light trespass, and blue light wavelengths. And particularly, blue lights are highly reflective—they're the ones that greatly disturb human and wildlife sensory systems. That's why many of us squint at the blue, LED car headlights driving toward us at night.

Legislation that Helps Reduce Light Pollution

Combatting light pollution is possible—through legislation and community action. Some countries and cities have already implemented change.

In 2019, the Senate of Mexico declared that light pollution is a form of environmental pollution. And it's subject to regulation under law. In 2020, Croatia also implemented strategies to decrease outdoor lighting by requiring cities to dim nighttime lights by 50%.

In the U.S., 19 states, Washington D.C., and Puerto Rico already have laws to reduce light pollution in order to "promote energy conservation, public safety, aesthetic interests, or astronomical research capabilities, according to the National Conference of State Legislatures. And now, Marlin is calling upon the Hawai'i County Council to take action, too.