Viennese Meteorologist: Microplastics from Road Traffic Could Affect Climate

The tiny plastic particles act like desert dust as ice nuclei, on which water droplets and vapor freeze. Over some world regions, up to 40 percent of the ice nuclei could consist of microplastics, he reports in the "Journal of Geophysical Research". Therefore, it should be considered in climate models.

"On its own, water in the atmosphere would only freeze near minus 40 degrees Celsius," said Andreas Stohl from the Institute of Meteorology and Geophysics at the University of Vienna in an interview with the APA. The freezing process would occur at about minus 18 degrees on an ice nucleus made of desert dust, while plastic particles require around minus 20 degrees Celsius. "Microplastic is therefore only a little less efficient as an ice nucleus than desert dust," he explained.

Little Data on Released Microplastics

With his research team, he wanted to investigate how significant the influence of microplastics on ice cloud formation is. "Unfortunately, there is hardly any reliable data available on how much of it actually reaches the atmosphere from various sources," said Stohl. For example, there are no reliable measurements or calculations of the amount emitted by the abrasion of synthetic fiber clothing or rising from the "Pacific Garbage Patch," an accumulation of thousands of tons of plastic waste in the northern Pacific.

"The best data is still on microplastic emissions from road traffic," he explained. They mainly arise from the abrasion of tires, brake pads, road markings, and asphalt. In the latter, the component bitumen is often mixed with plastic polymers to make it less brittle at low temperatures, more deformation-resistant, and more durable.

The researchers used computer models to calculate how much of this road traffic microplastic ends up in the air: Less than one to up to 40 percent of tire wear ends up in the atmosphere, one third to all of brake pad particles, one to four percent of markings, and ten percent to up to one third of polymers from road surfaces.

Microplastic Remains Much Longer in the Atmosphere Than Desert Sand

"This microplastic remains in the atmosphere up to seven times longer than, for example, desert sand," said Stohl. It is lighter, and its irregular shape compared to round sand grains also contributes to a more extended stay in the air. "This makes microplastic relatively important for cloud formation, especially in areas where there are hardly any natural ice nuclei from desert dust or spores," said the meteorologist.

Thus, microplastic could account for up to 40 percent of the ice nuclei in so-called mixed-phase clouds in the tropics, and up to 20 percent in cirrus clouds over Antarctica. "The difference between these two types of clouds is that in mixed-phase clouds, water droplets containing ice nuclei freeze, while in cirrus clouds, ice forms directly from water vapor," he explained.

The additional ice nuclei from microplastic can therefore make clouds significantly richer in ice in some regions. As a result, they reflect more light. Because the plastic particles float in the air longer than, for example, desert dust, this likely also extends their lifespan. This should be taken into account in future climate models, the expert suggests.

(APA/Red)

This article has been automatically translated, read the original article here.