The Earth simply can’t catch a break. Those microplastics that have invaded every corner of the globe — and even the insides of our bodies — may also be heating the planet, research suggests.

In a new study published in the journal Nature Climate Change, the authors found that microplastics are absorbing more sunlight than they reflect in the atmosphere, resulting in net heating. Its effects aren’t as powerful as greenhouse gases, but they’re significant enough to take notice of.

“We can say with confidence that overall they are warming agents,” study coauthor Drew Shindell, a professor of earth science at Duke University, told The Washington Post. “To me, that’s the big advance.”

Until now, the impact that microplastics have on the climate has largely been overlooked, and current climate models don’t even account for them. It’s a nascent avenue of research, and scientists are still grappling with their environmental toll and their potential harmfulness to human health.

In the study led by researchers at Fudan University in China, the team focused on an aspect of the pernicious particles that you likely never considered: their color. Color determines how much a material absorbs or reflects light, and therefore heat (beware black leather car seats on a hot summer day.) 

By testing how microplastics of different colors and sizes absorb heat in a lab setting, and simulating how this would play out in the atmosphere, the researchers found that microplastics could be generating up to one-sixth the warming as black carbon, or soot, with black, yellow, blue, and red particles in particular absorbing more sunlight than white ones.

It’s not a “trivial” amount, Shindell told WaPo. He calculated that a year’s worth of heating from microplastic pollution is roughly equal to 200 coal-fired power plants running over that same time period. But this doesn’t account for the long-term impact as the particles decay over decades and persist in the environment, the newspaper noted.

“We still have a lot to learn about exactly how many of these are in the atmosphere and how they’re distributed, both horizontally and vertically,” Shindell told Scientific American. “This is not the final word.”

This isn’t the only research to focus on airborne microplastics. Another study found evidence that they could be affecting the formation of clouds, and as a result influencing the weather. The floating particles provide a surface for liquid water droplets to cling to, forming ice crystals in clouds, the work found.

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