Plastic pollution not only enters the oceans, but also the atmosphere. So much so that researchers are concerned about possible unexpected effects on the environment and even… cloud formation.
Posted at 12:00 p.m
A dust of pollutants
PHOTO SUPPLIED BY JANICE BRAHNEY
Janice Brahney, Professor of Biogeochemistry at Utah State University
In 2017, Janice Brahney explored some of the most isolated regions of the American West. The professor of biogeochemistry at Utah State University has collected dust deposits in various federal protected areas. Their goal: to investigate the composition of the air far away from big cities – and the possible presence of phosphorus. Surprises awaited him. A multitude of colorful debris had become embedded in its samples. These fine plastic particles, called microplastics, came from everyday objects: clothing, packaging, cosmetics, etc. “I couldn’t believe my eyes,” she says. We calculated that around 4% of the dust collected is plastic. It’s enormous. To places so far away, all these pollutants could not have been transported by humans. The dust collected revealed alarming levels of microplastics circulating in the atmosphere.
A small strand goes a long way
PHOTO KIM RAFF, SPECIAL COLLABORATION OF THE ARCHIVES
A toxic cloud over the dry Great Salt Lake in Antelope Island State Park, Utah in 2022
In a 2020 article published in the journal Science, Janice Brahney’s team estimated that more than 1,000 tons of plastic are dumped in protected areas in the American West each year, the equivalent of 123 to 300 million bottles of plastic water. Other researchers have found them in the Arctic, Antarctica, and even in the snow near the top of Mount Everest. “Microplastics have been in the atmosphere for quite some time and we’re noticing it quite late, Professor Brahney fears. There are relatively large concentrations of it in the air over certain regions, and we don’t fully understand what that means for the environment and climate. »
In the spirit of the times
PHOTO ANTONIO BRONIC, Portal ARCHIVE
A plastic bottle floats in the Adriatic Sea near the island of Mljet, Croatia
Global plastic production continues to grow. According to the Organization for Economic Co-operation and Development (OECD), it doubled between 2000 and 2019 to over 450 million tons per year. Particles detach from these plastics and travel with wind and rain before being deposited back on land or sea. From the oceans they can be thrown back into the air by water bubbles. Air rising in the water and bursting on its surface. This is the microplastic cycle.
The power of aerosols
PHOTO SOE ZEYA TUN, Portal ARCHIVE
Plume of toxic smoke rises from an explosion at a plastics factory in Samut Prakan, near Bangkok, Thailand, in 2021.
According to recent models by Janice Brahney and her colleagues, some fine microplastic particles can stay in the atmosphere for a week and orbit the earth several times. In the air they mix with dust, soot, pollen and other suspended solids and liquids. This batch of particles, called “aerosols”, has a major impact on the climate. For example, some absorb solar radiation and have a warming effect, while others scatter it and have a cooling effect. The condensation of water vapor around the aerosols is the origin of the clouds. The more particles in suspension that the water agglutinates on, the more the sky becomes overcast.
A matter of properties
PHOTO PROVIDED BY DENISE MITRANO
Denise Mitrano, Professor of Environmental Sciences at the Swiss Federal Institute of Technology in Zurich
Until recently, microplastics were generally excluded from the study of cloud formation, as these pollutants tend to be hydrophobic. But some size factors have been overlooked. This is detailed in a recent article published in the journal Nature. “As plastic erodes, it is increasingly likely to participate in cloud formation processes,” says Denise Mitrano, Professor of Environmental Sciences at ETH Zurich and co-author of the article. “Some of the physico-chemical properties of eroded plastic are similar to those of particles that we already knew are involved in this process. Other substances in the environment can also attach to microplastics, making them more susceptible to cloud formation. Salts, sulfates, and organic materials in particular tend to attract water vapor.
The amount that matters
PHOTO LUIS ACOSTA, AGENCE FRANCE PRESS ARCHIVE
A toxic cloud rises after a fire at the Cerro Patacon landfill site in Panama on February 14.
What contribution does microplastic currently make to cloud formation? How can they influence the climate? The secret remains. In order to find out, these particles in the atmosphere and their importance compared to other aerosols would first have to be better quantified. “In areas like cities, there are already many other particles in the air and atmosphere,” notes Denise Mitrano. Microplastics should therefore only make up a small proportion. On the other hand, microplastics can be transported through the atmosphere to areas where less direct human activities release other particles. In these cases, microplastics could therefore be more important. Jennifer Brahney and her colleagues’ model estimates that microplastics typically make up less than 1% of man-made aerosols that land on land, but this proportion can rise to over 50% in some marine regions.
Much more than plastic
PHOTO PROVIDED BY LIISA JANTUNEN
Liisa Jantunen, Researcher at Environment and Climate Change Canada
Canadian Environment and Climate Change researcher Liisa Jantunen studies microplastics in the Canadian Arctic. Aside from the potential impact of these airborne particles on the climate, she is concerned about the risks to human and animal health. “Plastic itself has been linked to various types of inflammation in the body in the literature,” she points out. What I find most worrying, however, are all the substances, some of which are toxic, that are added to these plastics during their production, such as flame retardants and UV protection agents. »
wind of hope
PHOTO DRAGAN KARADAREVIC, ASSOCIATED PRESS ARCHIVES
A gray heron stands amidst a sea of plastic waste on the shore of Lake Potpeć on the Lim River in Serbia.
In response to the threat of plastic pollution, the United Nations Environment Program set up an intergovernmental negotiating committee made up of around 200 nations last March. The goal is to reach a legally binding agreement on plastics by 2024. Expectations are high for Liisa Jantunen. “I can imagine that it will take some time before the way things are handled in terms of plastic consumption changes,” she admits. But you know, humanity has to try. Otherwise it will only get worse. »
Learn more
More than 350 million tons of the world’s annual plastic waste
SOURCE: OECD
9% share of global recycling of plastic waste
SOURCE: OECD
9.2 billion tons Cumulative amount of plastic produced between 1950 and 2017
SOURCE: UNITED NATIONS ENVIRONMENT PROGRAM
34 billion tons Predict the cumulative amount of plastic that will have been produced between 1950 and 2050
SOURCE: UNITED NATIONS ENVIRONMENT PROGRAM