Microplastics have been found in some of the world’s most remote environments, from the snow-capped peaks of Mount Everest to the ocean depths of the Mariana Trench, infiltrating ecosystems and even the human body.
Now, a new study led by scientists at Penn State University (Pennsylvania) shows that these tiny plastic particles can also affect the atmosphere and climate. The study shows that microplastics can act as ice nucleating particles, potentially altering cloud formation, precipitation and even global climate patterns.
Microplastic as ice generator
Microplastics less than 5 millimeters in size were found to act as nucleating ice particles, microscopic aerosols that allow ice crystals to form in clouds.
“In research on microplastics over the last two decades, scientists have discovered that microplastics are everywhere, so this is another piece of the puzzle,” said Miriam Friedman, a professor of chemistry at the University of Pennsylvania and senior author of the study.
“It is now clear that we need to better understand how they interact with our climate system, because we have been able to show that microplastics can initiate the process of cloud formation.”
How was the research conducted?
The researchers examined four types of microplastics in their experiments: low-density polyethylene (LDPE), polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET). By suspending each piece of plastic in tiny water droplets and slowly cooling them, the team observed how these particles affected ice formation.
They found that droplets containing microplastics freeze at temperatures between -22 and -28 degrees Celsius; This is much higher than the typical -38 degrees Celsius required for error-free droplets to freeze.
“Any imperfection in a water droplet can cause something to form or nucleate around the ice, whether it’s dust, bacteria or microplastics,” said the study’s lead author Heidi Busse, a graduate student at the University of Pennsylvania.
Microplastics and weather conditions
The ability of microplastics to initiate cloud ice formation could lead to large-scale consequences on weather and climate. When clouds contain more ice, this can affect the structure of precipitation, often resulting in heavier precipitation as water droplets are delayed in landing until they reach a larger size.
“In a polluted environment with lots of aerosol particles, such as microplastics, you distribute the available water among more aerosol particles and create smaller droplets around each of those particles,” Busse said.
“When you have more drops, you get less rain, but since the drops only rain when they get big enough, you accumulate more water in the cloud before the drops are big enough to fall, and as a result, you get more precipitation in the cloud. Microplastics and cloud structure are coming.”
The effects of microplastics on cloud structure may also affect how much of solar radiation is reflected back into space or trapped in Earth’s atmosphere.
Clouds at higher altitudes can help trap heat radiating from the Earth, which can contribute to warming in some cases. Friedman emphasized that the liquid water/ice ratio in clouds plays a critical role in determining whether clouds have a net cooling or warming effect.
As microplastics accumulate in the atmosphere, their potential impact on mixed-phase clouds could mean they affect global climate in ways that are not yet fully understood.
Changing behavior of aging microplastics
The researchers also investigated how “environmental aging”—the natural processes that particles undergo when exposed to sunlight, ozone, and other elements in the atmosphere—affects the ice-forming properties of microplastics.
The analysis showed that aging generally reduces the ice-forming capacity of LDPE, PP and PET, while the ice-forming potential of PVC increases due to changes in its surface caused by environmental aging. This change indicates that as microplastics enter the atmosphere over time, their effects on cloud formation may change.
“We know that the fact that microplastics can form ice has far-reaching consequences; We’re not exactly sure what it is yet,” Busse said. “We can think about this on many different levels, not just in terms of stronger storms, but also in terms of changes in light scattering that could have a much larger impact on our climate.”
Future research on microplastic additives
Next, the team plans to study common additives such as plasticizers found in plastics to gain a more comprehensive understanding of how these substances may further influence the behavior of the atmosphere. Many plastics contain various additives that can affect their physical and chemical interactions in the environment. Analysis of these additional factors can provide more information about how microplastics in the atmosphere may affect weather and climate dynamics.
“We know that the entire life cycle of these plastic products that we use every day can change the physical and optical properties of clouds on Earth and therefore change the climate in some way, but we still have a lot to learn about what exactly they do,” Busse said.
As scientists continue to unravel the behavior of microplastics in the atmosphere, new discoveries could add to the growing list of impacts these particles have on global systems, from land and marine ecosystems to human health and now potentially climate.
The area of concern is growing
Microplastics are a relatively new problem in atmospheric and climate science, and researchers like Friedman are now beginning to link their widespread presence in the atmosphere to possible impacts on large-scale weather and climate systems. The study highlights the importance of understanding the full life cycle of plastic and its behavior in the environment, especially given the evidence that microplastics affect processes fundamental to Earth’s climate.
Although much remains to be known, Friedman’s team hopes to develop climate models that include microplastics and allow scientists to better predict how these particles might alter the planet’s delicate atmospheric balance. As research continues, microplastics will not only transform our understanding of environmental pollutants but may also inform future regulations aimed at mitigating their emissions and long-term impacts. The study was published in the journal Environmental Science and Technology: Air.
Source: Port Altele
