How Airborne Microplastics Affect Climate Change

(Scientific American)

Like other aerosols, these tiny particles scatter and absorb sunlight, influencing Earth’s temperature.

Microplastics—minuscule bits of bottles, bags, synthetic fibers and other plastic waste that have broken up in the environment—are influencing Earth’s climate as they circulate through the atmosphere. Like other aerosol particles, both natural and synthetic, microplastics seem to have an overall cooling effect (albeit a small one), according to the first study to look at the possible climate effects of airborne microplastics. The study’s authors and other researchers say the findings, published on Wednesday in Nature, show the urgent need to get a better handle on how much plastic debris is in the air, where it is and what it is made of in order to better pin down its climatic influence.

Microplastics are yet another kind of particle that humans are adding to the atmosphere “that has a climate impact. And that is big, and that is important, and we need to start accounting for that” when examining factors that affect Earth’s climate, says Deonie Allen, a microplastics researcher at the University of Strathclyde in Scotland. “This is the paper that opens that door,” adds Allen, who was not involved in the new study but has worked with the authors on other research.

All kinds of plastic waste crumble into smaller and smaller pieces when exposed to sunlight, wind, rain and other environmental conditions. Plastic’s generally low density means these fragments can easily be picked up by winds and blown around the world. In recent years, scientists have even found microplastics on remote mountain peaks and in the Arctic.

It occurred to researchers—including Laura Revell, an atmospheric scientist at New Zealand’s University of Canterbury and one of the new study’s authors—that all those particles swirling around the globe would intercept sunlight, as do other aerosols such as dust, sulfates and black carbon. This ultimately influences temperatures on Earth’s surface. Sulfates, for example, scatter radiation, exerting a cooling effect. Black carbon, on the other hand, absorbs visible and infrared radiation, warming the atmosphere.

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From Scientific American, Andrea Thompson, October 20, 2021