Airborne Plastic Has Climate Warming Effect

Colored microplastics in the air trap heat by absorbing light

microplastics

This is a summary of a story on Nicholas School of the Environment.

A Duke study has found that fragments of colorful airborne plastic are heating the planet. 

When plastic products break down, wind and water spray can sweep miniscule bits into the air, where they trap heat by absorbing light, according to the study. 

Researchers have long known that some floating particles, called aerosols, contribute to climate change. For example, soot is an aerosol that contains black carbon, one of the planet’s most potent warming agents.

“This research expands the family of aerosols that are actually causing warming, and that makes [microplastics] a particularly good target,” for climate action, says coauthor Drew Shindell of the Nicholas School of the Environment.

Old climate models indicated that airborne microplastics — which researchers assumed to be colorless — were negligible contributors to warming. Indeed, colorless atmospheric aerosols, such as water droplets in clouds, actually cool the planet by reflecting sunlight away from Earth.

Shindell’s research tells a different story.

Using computer simulations and lab experiments, the team analyzed how light and heat interact with tiny bits of plastic. They found that these particles come in varied colors that intensify with age. Those hues give this debris warming power: Pigmented microplastics absorb roughly 16% as much heat as black carbon. 

The researchers also predicted where these airborne microplastics exist globally. Unlike black carbon, which concentrates largely over land, airborne microplastics congregate over a region of the ocean called the North Pacific Subtropical Gyre.

This massive system of ocean currents spans nearly 8 million square miles, collecting plastic debris. When waves break over this detritus, sea spray launches microplastics into the air.

Currently, microplastics don’t appear to be a major climate threat, according to Shindell. But he hopes his study, which focused on airborne microplastics closest to Earth’s surface, will inspire other teams to measure microplastics throughout the lower atmosphere for a more complete picture of their effects on warming. 

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