Distinction between night and day disappearing due to light pollution: Study

From 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year.

Distinction between night and day disappearing due to light pollution: Study
Image courtesy: Thomas Pesquet/NASA (Representational image)

New Delhi: Is the Earth losing its night light? According to a new study, Earth is in danger of losing its night-time darkness – at a huge cost to flora, fauna and human well-being – due to light pollution.

While LED lights were supposed to reduce energy consumption and light pollution, cheaper efficiencies encouraged people to light up more areas than ever, increasing both the extent and the brightness of artificial lights across the planet.

According to a paper published Wednesday in the journal Science Advances, the most heavily populated regions of the Earth are worst affected since the distinction between day and night is disappearing, causing a rapid shift with profound consequences for human health and the environment.

As per a report in Forbes, “Major arguments for transition to LEDs for outdoor lighting are cost savings and reductions in energy consumption,” the study said. “These goals have been realized in many cities that have switched to LED street lights, and therefore, decreases in observed… radiance likely indicate local energy savings.

“However, on the global (and often national) scale, these local decreases are outweighed by increases in radiance in other areas, most likely because of additional lighting being installed. This should not be surprising, because decreases in cost allow increased use of light in areas that were previously unlit, moderately lit, or lit only during the early evening hours. The “energy saving” effects of outdoor LED lighting for country-level energy budgets are therefore smaller than might be expected from the increase in luminous efficacy compared to older lamps.”

From 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries, the study in Science Advances said.

These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.

Much of the increase is concentrated in the Middle East and Asia. The observed "decrease" in western Australia is actually due to wildfires in 2012 that were visible from space.

These observations probably understate the true increase in lit areas and light intensity because the satellites used in the study are not sensitive to blue light wavelengths emitted by LED lights, the Washington Post reported.

The shift from incandescents to LEDs has been directly observable from space.

People are particularly attuned to the short-wavelength blue light emitted by most LEDs, but it's been implicated in sleep deficiencies and other human health problems. Last year, the American Medical Association issued a warning about health risks associated with this type of light.