Microplastics in Atmosphere Found to Influence Cloud Formation, Climate, Study Finds

Microplastics, minuscule particles widely found in environments from deep oceans to mountaintops, have now been shown to affect cloud formation by facilitating ice crystal growth at temperatures 5 to 10 degrees Celsius (9 to 18 degrees Fahrenheit) warmer than conditions without them, according to a newly published study.

Atmospheric chemists conducting this research demonstrated that these tiny plastic particles serve a similar function as natural particles, like dust, in catalyzing ice formation within clouds, a process known as nucleation.

The study, conducted by chemists who specialize in particle interaction with liquid water in the atmosphere, found that microplastics could influence cloud formation and, subsequently, precipitation patterns. Typically, ice crystals form in clouds at altitudes with temperatures between 0 and –38 degrees Celsius (32 and –36 degrees Fahrenheit), often nucleating around dust or biological particles.

Microplastics, generally less than 5 millimeters in size and sometimes microscopic, can travel through the air and have been detected in even the most remote environments, like Antarctic snow and the peaks of Mount Everest.

The formation of ice within clouds plays a critical role in weather as it often triggers precipitation. In colder air, clouds with high enough altitude experience freezing, where ice particles grow heavy and fall as precipitation. Without ice development, clouds are likely to dissipate without producing rain or snow.

To observe the role of microplastics in ice nucleation, researchers examined four common types: low-density polyethylene, polypropylene, polyvinyl chloride, and polyethylene terephthalate. These were tested under pristine conditions and following exposure to ultraviolet light, ozone, and acids—conditions that microplastics would encounter in the atmosphere. The team suspended these particles in water droplets and slowly cooled them, measuring the temperature at which freezing occurred.

The findings suggest that microplastics could indeed alter cloud composition, potentially influencing Earth’s energy balance. Clouds reflect sunlight, cooling the Earth, but they also trap some heat, causing a warming effect. The balance between liquid water and ice in clouds determines their impact on Earth's climate.

Microplastics demonstrated nucleation activity even when exposed to environmental conditions that decreased their effectiveness, meaning they could still contribute to ice presence in clouds. Another study similarly found that certain microplastics induced ice formation at relatively warmer temperatures.

Further research is needed to quantify microplastic concentrations at cloud-forming altitudes and to compare them with other particles, like mineral dust and biological matter. Researchers also plan to investigate how other additives within plastics might influence ice nucleation.