It's widely known that microplastics are choking the ocean, but it's less known they are also swirling around in Earth’s atmosphere – and may even be having a subtle effect on the planet’s climate.
Tiny airborne particles, from volcanic ash to human-made smog, have varying influences on the climate by reflecting or absorbing solar radiation. It’s also known that microplastic particles can drift around our atmosphere, traveling vast distances on ribbons of wind. Now, for the first time, scientists from Victoria University of Wellington and the University of Canterbury in New Zealand investigated whether airborne microplastics could also have an effect on our climate.
Reported in the journal Nature, their models suggest that the current amount, distribution, and types of microplastics circulating in the Earth’s atmosphere may be warming and cooling our climate, albeit to a relatively minor extent.
"We investigated how airborne microplastics behave: do they warm or cool Earth’s atmosphere? It turns out that they do both. Overall, airborne microplastics are efficient at scattering sunlight which implies a cooling effect on climate. However, they can also absorb radiation emitted by the Earth meaning that they contribute, in a very small way, to the greenhouse effect," Dr Laura Revell, lead study author and University of Canterbury atmospheric chemist, said in a statement.
"The actual magnitude of microplastics’ influence on climate varies in our climate model simulations, depending on assumptions we made about how microplastics are distributed throughout Earth’s atmosphere," she explained
"Our research shows that the influence of microplastics on global climate is currently very small. However, it is expected to increase in future: an estimated five billion tonnes of plastic waste have accumulated in landfills or the environment to date, and this figure is projected to double over the next three decades," added Dr Revell.
There's scarcely a nook or cranny on our planet where microplastics haven't been detected, from Antarctic ice to the innards of humans. Broadly speaking, the effects of microplastic on animal health are not widely agreed upon. Nevertheless, this field of research is still relatively young and there are many unknowns. As it stands, there appears to be an emerging pile of evidence that suggests microplastic exposure in humans may have a link to metabolic disturbances and neurotoxicity, as well as carcinogenic effects.
While the team conceded their findings are hampered by very limited data on the issue, they argue this could be something to look out for in the future, especially as plastic pollution continues to mount.