How Microplastics Are Likely Helping To Heat Up the Planet
A new Nature Climate Change study suggests airborne microplastics -- especially darker and colored particles -- are likely contributing to atmospheric warming by absorbing more heat than they reflect. Researchers estimate the effect could be roughly one-sixth that of black carbon, though outside experts say the uncertainties remain large and more study is needed before drawing firm policy conclusions. "We can say with confidence that overall they are warming agents," said Drew Shindell, a Duke University earth science professor and co-author of the study. "To me, that's the big advance." The Washington Post reports: To undertake their study, a group led by researchers at Fudan University in China examined how different colors and sizes of microplastics interact with light across the spectrum, while combining that information with simulations of how particles get dispersed in the air across the planet. "Black, yellow, blue and red [particles] absorb sunlight much more strongly than the white particles," Yu Liu, a Fudan professor and study co-author, said in a call with reporters. In fact, the study details how black and colored particles showed "absorption levels nearly 75 times higher than pristine, non-pigmented plastics." The scientists also found that different sizes of particles absorb light at different intensities -- and that how they absorb light can change as they age.
The authors estimate that microplastics suspended in the atmosphere could be contributing to global warming at about one-sixth the amount of black carbon, also known as soot, a pollutant generated largely from burning fossil fuels. If the latest estimates are right, Shindell said, microplastics might not be an enormous source of atmospheric warming, compared with massive contributors such as cars and trucks, belching industrial plants or even burping cows. "But not a trivial one, either," he said.
By his calculation, the effect of one year's microplastic emissions globally is approximately equivalent to 200 coal-fired power plants running for that year. But that rough estimate does not factor the longer-term repercussions of microplastics decaying and persisting in the environment for decades to come. Whatever the exact impact, the topic deserves further study, the authors say, because current climate modeling does not account for any additional warming that these tiny particles might be causing.
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