Microplastics in the atmosphere are heating the planet, magnifying climate change impacts, according to new research.
Scientists in China and the US found that tiny, coloured plastic particles absorb sunlight as winds blow them around the world, trapping heat and contributing to temperature rise, according to the peer-reviewed paper published on May 4 in the journal Nature Climate Change.
“The plastic problem is not just in our blue oceans, it is also in the invisible skies above us,” Professor Hongbo Fu, a co-author of the study and an atmospheric scientist at Fudan University in Shanghai, said at a press conference. “Climate models need to be updated.”
The researchers’ laboratory experiments and atmospheric modelling indicate that airborne plastic pollution has 16.2 per cent of the heat-trapping impact of black carbon, the second biggest contributor to global warming after carbon dioxide. That effect is small on a global scale, according to the scientists, but can be significant in areas with high volumes of plastic, such as parts of the Pacific Ocean. There, plastic particles had 4.7 times the impact of black carbon.
Scientists had previously detected the presence of nanoplastics and microplastics, which range in size from a billionth to a millionth of a meter, in the atmosphere. As plastic waste washes into the ocean and litters the landscape, it breaks down into smaller and smaller pieces when exposed to sunlight until winds sweep the particles into the atmosphere, where they become suspended in air currents.
The planet is awash in plastic trash and its deleterious consequences for the environment, wildlife and human health is the subject of ongoing study. But past research suggested that microscopic plastic has a negligible impact on global warming, as white-coloured plastic particles reflect sunlight.
The scientists at Fudan University, however, found that the majority of plastic particles in the atmosphere are coloured and trap heat. Professor Drew Shindell, a climate scientist at Duke University and a co-author of the paper, said their experiments break new ground by precisely measuring the rate at which different-coloured particles absorb sunlight.
He said atmospheric plastic particles either are already dark, or lighter ones darken as they age. “The net effect is warming,” said Prof Shindell.
Those impacts are maximised in regions of the world where plastic pollution is concentrated, such as in the Texas-sized Great Pacific Garbage Patch that lies between California and Japan, the researchers said.
Typhoons and tropical cyclones can also create atmospheric hotspots and affect regional climate patterns as strong winds suspend more plastic particles in the air. A super typhoon in 2023, for instance, caused a nearly 51 per cent increase in the atmospheric concentration of nanoplastics, according to the paper.
The scientists said the effects from such extreme weather would likely be strong but short-lived in the immediate area.
Exactly how much warming is attributable to plastic remains to be determined due to the difficulty of measuring the concentration of particles in the global atmosphere and the rates at which they enter the air from the ocean or land. That means the researchers could be underestimating or overestimating the impact on climate change.
“We need more measurements from all around the world to really characterise more precisely how much of the stuff is in the atmosphere,” said Prof Shindell. BLOOMBERG
