Mt. Fuji, straddling Shizuoka and Yamanashi prefectures in central Japan, on Aug. 11, 2023. (Photo by Kyodo News via Getty Images)
Japanese researchers have found that microplastics in cloud water affect cloud formation and could worsen climate change.
For their research, published in the journal Environmental Chemistry Letters, the scientists collected cloud water from the summit of Mount Fuji and its southeastern foothills, as well as from the summit of Mt Oyama — regions at altitudes ranging from 1 300m to 3 776m — to investigate the effect of these airborne microplastics in the troposphere (the lowest region of the atmosphere) and the atmospheric boundary layer.
Nine different types of polymers and one type of rubber were found in the microplastics, at concentrations ranging from 6.7 to 13.9 pieces per litre of cloud water and at sizes from 7.1 to 94.6 micrometres.
The scientists also found an abundance of hydrophilic (water loving) polymers in the cloud water, suggesting that they were removed as “cloud condensation nuclei”.
These findings confirm that airborne microplastics “play a key role in rapid cloud formation”, which may eventually affect the overall climate.
Most studies on microplastics have focused on aquatic ecosystems. “To the best of our knowledge, this is the first report on airborne microplastics in cloud water,” they noted in their study, which was led by Hiroshi Okochi, a professor at Waseda University in Tokyo.
“Microplastics in the free troposphere are transported and contribute to global pollution,” he said. “If the issue of plastic air pollution is not addressed proactively, climate change and ecological risks may become a reality, causing irreversible and serious environmental damage in the future.”
Microplastics are less than 5mm in size and often found in industrial effluents, or form from the degradation of bulkier plastic waste. Large amounts of microplastics are ingested or inhaled by humans and animals and have been detected in the lung, heart, blood, placenta and faeces.
Ten million tonnes of these plastic bits end up in the ocean, released with the ocean spray, and find their way into the atmosphere, the researchers said. This implies that microplastics may have become a component of clouds, “contaminating nearly everything we eat and drink via ‘plastic rainfall’”.
The accumulation of airborne microplastics in the atmosphere, especially in the polar regions, could unleash significant changes in the ecological balance of the planet, leading to the severe loss of biodiversity, the research team said.
“Airborne microplastics are degraded much faster in the upper atmosphere than on the ground due to strong ultraviolet radiation, and this degradation releases greenhouse gases and contributes to global warming,” Okochi said, adding that the study’s findings can be used to account for the effects of airborne microplastics in future global warming projections.