How Are Microplastics Affecting Climate Change?

By Owais AliReviewed by Lexie CornerFeb 11 2025

Microplastics (plastic particles <5 mm) pose an emerging threat to global climate systems. These microscopic particles, formed from plastic waste degradation, are increasingly infiltrating terrestrial, aquatic, and atmospheric environments. Their ability to accumulate toxic chemicals, disrupt carbon sequestration, and alter environmental processes makes them significant yet often overlooked contributors to climate change.

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Carbon Cycle Disruption

The ocean, Earth's largest carbon reservoir, regulates climate by transferring atmospheric CO₂ into the deep sea through the biological carbon pump. This system facilitates atmospheric CO₂ transfer through a two-step process: atmospheric CO₂ dissolution into surface seawater, followed by phytoplankton incorporation of carbon through photosynthesis. The subsequent consumption of phytoplankton by zooplankton creates carbon-rich fecal pellets that sink to the ocean floor, enabling long-term carbon sequestration.

However, microplastic pollution disrupts this cycle by attaching to phytoplankton surfaces, obstructing light and CO₂ absorption, reducing carbon fixation rates by up to 45 %, and impairing essential cellular functions necessary for growth and reproduction.¹

Recent studies indicate that phytoplankton exudates, particularly extracellular polysaccharides, influence microplastic behavior by promoting flocculation and surface adhesion. This process affects the transport, aggregation, and potential bioavailability of microplastics in marine environments.

For instance, species like Tetraselmis suecica release exopolymers that enhance microplastic aggregation, altering their interactions with marine organisms. Additionally, bacterial biofilms contribute to microplastic adhesion, further impacting their movement through the ecosystem and their integration into food webs.²

This disruption extends to higher trophic levels, as zooplankton consuming microplastic-laden phytoplankton experience reduced feeding efficiency and reproductive success. Accumulated particles in their digestive systems lead to decreased egg size, lower fecundity, and increased mortality among copepods and other zooplankton species.

Additionally, contaminated fecal pellets exhibit slower sinking rates, with polystyrene-laden pellets descending up to 1.76 times slower and salp feces sinking 1.47 times slower, delaying carbon transport by 7-8 weeks. This prolonged transport time weakens the ocean's ability to sequester atmospheric CO₂ efficiently, potentially exacerbating climate change by increasing CO₂ retention in surface waters.³ The density mismatch between common polymers (e.g., polystyrene with a density of ~1.05 g/cm³) and seawater (~1.02 g/cm³) is a key factor driving these slower sinking rates.

Interaction with Marine Systems

Marine ecosystems regulate global climate through complex biological and chemical processes, with deep ocean environments playing a crucial role in nutrient cycling and oxygen regulation.

Microplastic contamination disrupts these processes, altering sediment microbial communities responsible for nitrogen cycling and exacerbating harmful algal blooms. Additionally, microplastic ingestion reduces zooplankton grazing on phytoplankton, leading to surface accumulation of decaying organisms, oxygen depletion, and worsening ocean deoxygenation, which has already caused a greater than 2 % oxygen loss since 1960.⁴

Recent research suggests that microplastic-associated additives, such as phthalates leaching from polyvinyl chloride (PVC) particles, can further disrupt microbial activity in sediments. These additives, particularly di(2-ethylhexyl) phthalate (DEHP), are known to interfere with enzymatic pathways involved in nitrogen cycling, leading to inhibited nitrification and denitrification.⁵

Photoaging of PVC microplastics accelerates the release of DEHP and its transformation products, such as mono(2-ethylhexyl) phthalate (MEHP) and phthalic acid, further altering microbial composition and function.⁵

Additionally, certain plastics like polyurethane foam (PUF) and polylactic acid (PLA) can stimulate nitrogen cycling by serving as carbon substrates for microbial communities, while PVC inhibits these processes, highlighting the material-dependent impact of microplastics on sedimentary biogeochemical cycles.⁶

Coral reefs, which support 25 % of marine biodiversity and protect coastal regions by buffering wave energy, take thousands to millions of years to fully form and are highly vulnerable to microplastic exposure. A study on northern star corals reported up to 112 plastic particles per polyp, with 73.4 % originating from synthetic textile fibers. These fibers are particularly problematic due to their high tensile strength and resistance to biodegradation, leading to gut blockages and reduced nutrient intake.

Microplastics also exacerbate coral bleaching by disrupting algal colonization and inducing apoptosis in symbiotic dinoflagellates like Cladocopium goreaui, with polyethylene microplastics further inhibiting photosynthetic efficiency, especially under ocean acidification conditions.^3,7

Robotic Solutions for Microplastic Removal

Effects on Heat Absorption in Oceans

The accumulation of microplastics in marine ecosystems influences oceanic heat absorption by altering surface waters' reflectivity (albedo) and optical properties.

These particles, often less dense than seawater, accumulate in the sea surface microlayer, influencing the reflection and absorption of solar radiation. Their optical properties vary based on polymer composition and color, with darker particles—such as black, gray, or brown—absorbing more solar radiation.

This absorption increases local water temperatures, disrupting ocean currents by altering water density and circulation patterns, potentially affecting regional and global climate systems.⁸

Materials scientists are thus investigating advanced coatings or additives that could reduce the absorptivity of plastics without compromising their mechanical properties.

Release of Greenhouse Gases (GHGs)

Microplastic pollution contributes to greenhouse gas (GHG) emissions through direct and indirect pathways.

Direct emissions arise from plastic degradation and waste management, varying by disposal method and environmental conditions. For example, photodegrading plastics release methane and ethylene at rates of 10–4,100 pmol and 20–5,100 pmol per gram per day, with emissions increasing under UV exposure and rising temperatures.⁹ The degradation kinetics depend heavily on polymer crystallinity; amorphous regions degrade faster than crystalline regions due to higher molecular mobility.

Indirect emissions arise from plastic production, landfill degradation, and ecosystem disruption. For instance, in 2020, global plastic manufacturing consumed 150 million tons of ethylene and 95 million tons of propylene, generating 1.8 gigatons of CO₂-equivalent emissions.

Microplastics further exacerbate emissions by disrupting soil microbial activity, altering carbon and nitrogen cycles. A recent study demonstrated that soils with 18 % microplastic content experience a 28.67 % rise in CO₂ flux, as microbial stress reduces carbon-use efficiency, increasing emissions.^1,9

Microplastics in the Atmosphere

Atmospheric circulation transports microplastics globally, with detections in remote regions such as the Pyrenees and Antarctic snow, demonstrating their widespread distribution and potential climate impact.

A recent study revealed that microplastics act as cloud condensation nuclei (CCN) and ice nucleation particles (INP), acquiring hydrophilic functional groups through weathering. These properties facilitate ice formation at 5–10 °C above normal thresholds, influencing precipitation patterns and atmospheric water cycling.

Microplastics also contribute to radiative forcing, with values reaching 0.1 W/m², comparable to established atmospheric aerosols. In regions with high microplastic concentrations, surface temperature variations of up to 0.2 °C have been documented, particularly in urban and industrial areas where particle densities exceed 100 per cubic meter. These thermal anomalies can create localized atmospheric instability, affecting weather patterns.

Stratospheric microplastics further complicate atmospheric chemistry by interacting with ozone-related processes, potentially modifying UV radiation penetration and altering large-scale circulation dynamics. Numerous studies suggest that microplastic-laden air masses influence vertical mixing and precipitation development, though the long-term climatic consequences remain under investigation.^3,10,11

Conclusion: The Overlooked Link

Microplastics threaten global ecosystems and climate stability by disrupting carbon cycles, altering atmospheric processes, and generating greenhouse gas emissions. With plastic-related emissions projected to reach 56 gigatons by 2050, comprehensive waste management, pollution control, and sustainable material innovations are urgently needed to mitigate their long-term environmental impact.

 How Does Climate Change Affect Microplastic Degradation?

References and Further Reading

1. Abdullayeva, M., Yaqubov, R. (2024). Microplastics and Climate Change: Analyzing the Environmental Impact and Mitigation Strategies. IOP Conference Series: Earth and Environmental Science. https://doi.org/10.1088/1755-1315/1405/1/012034
2. Sakhon, EG., et al. Phytoplankton Exopolymers Enhance Adhesion of Microplastic Particles to Submersed Surfaces. Ecologica Montenegrina. https://www.biotaxa.org/em/article/view/em.2019.23.8
3. Parvez, M., et al. (2024). Role of Microplastics in Global Warming and Climate Change: A Review. Water Air Soil Pollut. https://doi.org/10.1007/s11270-024-07003-w
4. Asher, C. (2023). Microplastics pose risk to ocean plankton, climate, other key Earth systems. [Online] Mongabay. Available at: https://news.mongabay.com/2023/10/microplastics-pose-risk-to-ocean-plankton-climate-other-key-earth-systems/
5. Henkel, C., et al. (2024). Photoaging enhances the leaching of di(2-ethylhexyl) phthalate and transformation products from polyvinyl chloride microplastics into aquatic environments. Communications Chemistry. https://www.nature.com/articles/s42004-024-01310-3
6. Seely, ME., et al. (2020). Microplastics affect sedimentary microbial communities and nitrogen cycling. Nature Communications. https://www.nature.com/articles/s41467-020-16235-3
7. Bednarz, V., et al. (2021). The Invisible Threat: How Microplastics Endanger Corals. [Online] Frontiers. Available at: https://kids.frontiersin.org/articles/10.3389/frym.2021.574637
8. Conti, GO., et al. (2024). Relationship between climate change and environmental microplastics: a one health vision for the platysphere health. One Health Adv. https://doi.org/10.1186/s44280-024-00049-9
9. Li, K., et al. (2024). Microplastic pollution as an environmental risk exacerbating the greenhouse effect and climate change: a review. Carbon Res. https://doi.org/10.1007/s44246-023-00097-7
10. Jones, N. (2023). Microplastics Are Filling the Skies. Will They Affect the Climate? [Online] Yale. Available at: https://e360.yale.edu/features/plastic-waste-atmosphere-climate-weather
11. Busse, HL., Ariyasena, DD., Orris, J., Freedman, MA. (2024). Pristine and aged microplastics can nucleate ice through immersion freezing. ACS ES&T Air. https://doi.org/10.1021/acsestair.4c00146

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