Artificial Lights Tell the Story of the Pandemic – The Atlantic

Some changes have coincided with the implementation of emergency measures meant to slow the transmission of the fast-spreading virus. The effect was stark in China, according to Qian Liu, a doctoral student in geography at George Mason University in Virginia. Liu and her fellow researchers used images from a weather satellite to examine the average nighttime radiancea measure of artificial light on the groundacross the countrys provinces. They found that radiance levels decreased from December, when the first coronavirus cases were reported, to January and February, when officials put entire cities on strict lockdowns.

Near Wuhan, the city where the virus first emerged, the data showed that residential areas brightened while commercial areas dimmed this springa sign that more people were staying home than usual. In China, peoples commercial areas and living areas are separate, Liu says. The levels appeared to return to normal as provinces lifted restrictions in March, with the exception of Hubei, where Wuhan is located, which remained under quarantine until April.

Christopher Elvidge, a researcher who specializes in nighttime observations of light sources at the Colorado School of Mines, found similar effects in the U.S. Analyzing data from the same satellite that Lius team used, Elvidge and his colleagues found that from February to March, artificial light dimmed in states such as New York and California, which were among the first to introduce widespread stay-at-home orders, but remained unchanged in states such as Florida and Arizona, which took a less stringent approach.

Satellite data might have even captured the result of plummeting oil prices. In late April, as U.S. oil prices dropped below zero for the first time in history, oil fields in Texas appeared significantly dimmer compared with satellite images taken three months earlier. As demand had diminished worldwide, oil companies had sharply cut their operations, which apparently eliminated the need to keep their deserted sites lit.

Such views can tell us only so much, though; weather satellites arent spy satellites, and their resolution at night isnt good enough to resolve small-scale sources of artificial light. When researchers spot dimming in a particular region, we cant necessarily say, Okay, this was advertising lighting that turned off, or, People went to bed earlier, or, Theres less traffic, says Christopher Kyba, a researcher at the German Research Center for Geoscience who studies the ecological impacts of nighttime artificial light.

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Artificial Lights Tell the Story of the Pandemic - The Atlantic