Microplastics could be affecting the weather, new study shows

Microplastics have already been found in the remotest parts of the world, including Antarctica - and a new study suggests they could be affecting the weather.

Microplastics, which are formed when plastic in the environment breaks down into tiny particles, have also been found in plant roots and human organs - and now scientists believe they could be affecting how clouds form.

The finding could mean that plastic pollution may influence rainfall, potentially worsen climate change - and even pose risks to planes. The new Penn State research builds on previous studies, which showed that microplastics affected clouds.

What did the new study find?

The study showed that microplastics help ice crystals form inside clouds by acting as ‘ice nucleating particles’, the researchers say.

Using four common plastics, the researchers simulated water droplets freezing inside a cloud. They found that droplets with microplastic particles froze at temperatures 5 to 10 C higher than droplets without plastic pollution.

Lead author Heidi Busse, a graduate student at Penn State, said that any defects in water droplets (including dust or bacteria) can make droplets freeze at higher temperatures, and microplastics also do this.

What does it mean?

What the finding means for weather and climate is unclear - but with clouds having a role in ‘trapping’ heat, it could boost climate change.

It could also lead to heavier rain.

Miriam Freedman, professor of chemistry at Penn State, said that microplastics are probably already having an impact on weather.

‘Mixed-phase’ clouds including cumulus and nimbus clouds (and the ‘anvil’ clouds that form during thunderstorms) can contain both water and ice.

Freedman says, “When air patterns are such that a droplet gets lifted into the atmosphere and cools, that’s when microplastics could be affecting weather patterns and forming ice in clouds.

“In a polluted environment with many more aerosol particles, like microplastics, you are distributing the available water among many more aerosol particles, forming smaller droplets around each of those particles.

"When you have more droplets, you get less rain, but because droplets only rain once they get large enough, you collect more total water in the cloud before the droplets are large enough to fall and, as a result, you get heavier rainfall when it comes.”

It could also affect climate change, Freedman says.

In general, clouds cool the Earth by reflecting solar radiation, but certain clouds at certain altitudes can have a warming effect by helping to trap energy emitted from the Earth.

What has other research shown?

Previous research in 2023 found that plastics from clouds had been carried to mountain summits - and that microplastics tended to become better at forming droplets as they travel from the sea to the sky and back to the sea again.

The research suggested that as microplastics linger in the environment they become better at triggering cloud formation.