Microplastics are absorbing heat in the atmosphere and contributing to global warming, a new study reveals.

Microplastics are infamous for being everywhere, contaminating ecosystems and accumulating inside our bodies. Scientists have known for a while that plastics are also blown high into the atmosphere, where they are now pervasive, but it was unclear what impact they might be having up there.

Now, the new study, published Monday (May 4) in the journal Nature Climate Change, has found that overall, plastic particles create a warming effect. This is because, while very-light-colored plastics scatter sunlight back into space, darker-colored plastics absorb sunlight and radiation.

Study co-author Drew Shindell, a distinguished professor of Earth science at Duke University, told Live Science that the climate change impact of plastic particles is fairly small  —  comparable to the emissions of a small country. In numbers, this is the equivalent of around a couple of percent of the contribution from carbon dioxide (CO2) — the main driver of climate change — or a couple hundredths of a degree of warming. However, the researchers' modeling was based on a limited understanding of the amount of plastic in the atmosphere, so the extent of the warming effect is uncertain.

"The key finding is really that the warming strongly outweighs the cooling," Shindell said. "I think we have a lot of confidence in that because we did all of these measurements in the laboratory of how [microplastics and nanoplastics] interact with sunlight. What we don't have so much confidence in and what's still a big uncertainty is exactly how many of these are in the atmosphere."