Humans Changed the Clouds—and It Now Might Be Affecting Weather

Microplastics have infiltrated nearly every environment on Earth, from the deep sea to the skies—and now it seems they may even be able to influence the weather.

Floating up into the air above mountains, they may be able to trigger cloud formation, and as a result affect the weather in certain regions, according to a new study in the journal Environmental Science & Technology Letters.

Microplastics are tiny fragments of plastic smaller than 0.2 inches—around the same size as a sesame seed—and result from the degradation of a variety of plastic sources, from synthetic clothing and car tires to plastic bottles and cosmetic microbeads. There are an estimated 50 to 75 trillion microplastics floating in ocean surface waters worldwide.

They have also found their way into our bodies, with humans inhaling around 16.2 pieces of microplastic every hour, the equivalent of roughly a credit card's worth per week.

"Plastics also contain a suite of chemicals, some of which may be transferred to humans via ingestion. However, there has been very little research carried out to date which has looked at the risks associated with the secondary transfer of plastics and associated chemicals to humans," Isabella Clere, a coastal scientist for New Zealand's Gisborne District Council, told Newsweek.

The Environmental Science & Technology Letters study looked at a different aspect of the problem. It describes how researchers from China's Shandong University collected 28 samples of liquid from clouds at the top of Mount Tai in eastern China, to test how they interacted with clouds.

They discovered that lower-altitude clouds contained more microplastics, as did more dense clouds, and that these microplastics were usually made of common polymers, including polyethylene terephthalate, polypropylene, polyethylene, polystyrene and polyamide. They tended to be tiny, smaller than 100 micrometers across (0.004 inches), though some were larger at around 1.5 mm (0.06 inches).

The longer the particles had spent in cloud-like conditions, exposed to ultraviolet light and filtered cloud-sourced water, the rougher they were, and therefore had more mercury, lead and oxygen attached to their surfaces. The researchers suggested that this may enable them to trigger cloud development.

Previous studies have also found that microplastics can act as cloud seeds, bonding with water molecules in the air and acting as a nucleation point for clouds to form around.

Using computer models, the researchers in the latest study estimated how microplastic particles had made their way to Mount Tai. They found that they likely traveled via airflow from highly populated inland areas rather than from the ocean or other mountains.

The researchers hope to carry out more research into how microplastics and clouds interact, and how this affects the weather.

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