1 Introduction

Plastic pollution is a major global environmental challenge that has drawn increasing attention (Syberg et al. 2021). Research shows that only 60% of the 250 million tons of global plastic waste generated annually is collected (Skoczinski et al. 2021). The uncollected plastic waste undergoes physical and chemical processes, such as weathering and ultraviolet (UV) radiation, breaking down into small plastic particles that disperse throughout the environment (Duan et al. 2021). Microplastics (MPs) are plastic particles with a diameter smaller than 5 mm (Thompson et al. 2004). Due to their large surface area, hydrophobicity, and resistance to degradation, MPs can serve as carriers for heavy metals and numerous hydrophobic organic compounds (Bradney et al. 2019), posing a long-term threat to environmental and ecological safety (Sridharan et al. 2021). Many studies have shown that human factors can have a huge impact on the distribution of microplastics in the environment, such as hydropower dams, which disrupt the transport mode of river MPs into the ocean and promote the deposition of microplastics in reservoir sediments (Xu et al. 2022a). The Three Gorges Dam in China retains microplastics in up to 8048 ± 7494 tons of sediment per year, equivalent to 47% ± 44% of the Yangtze River’s Marine MPs flux (Gao et al. 2023). Floods, on the other hand, re-suspend most of the MPs stored in sediments (70%), thereby diffusing MPs into terrestrial ecosystems (Hurley et al. 2018). As an emerging class of environmental pollutants, research on MPs pollution in various environmental media, including oceans, land, and the atmosphere, has been accelerating in recent years, and the associated environmental and health issues have garnered significant attention (Ren et al. 2022).

Global warming resulting from climate change is one of the main consequences of human activities (Al-Ghussain 2019). The excessive use of fossil fuels as energy sources has led to an increase in the concentration of greenhouse gases (GHG) in the atmosphere, which is the primary cause of the recent rise in the Earth’s average surface temperature (Liu et al. 2019b). In the atmosphere, carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) are the primary GHG, contributing to over 80% of the total greenhouse warming effect (Saunois et al. 2020; Tian et al. 2020). Studies have shown that GHG emissions mainly come from the development and combustion of fossil fuels (Paredes et al. 2019), food production systems (Crippa et al. 2021), wetlands (Su et al. 2022), and oceans (Steinhoff et al. 2019). Factors contributing to GHG emissions include climate, vegetation (Li et al. 2018), soil composition (Deng et al. 2020), water condition (Li et al. 2021), geographical conditions, and anthropogenic factors (Zheng and Suh 2019). The continuous emissions of GHG are causing various climate disasters including extreme weather events that may impact humanity, such as warming, heatwaves, precipitation changes, droughts, floods, wildfires, storms, sea-level rise, and alterations in natural land cover and ocean chemistry (Mora et al. 2018). The urgency to address global climate change caused by GHG emissions is increasing (Shi et al. 2020).

Currently, an increasing number of studies are focusing on the undeniable contribution of plastics to global GHG emissions and climate change (Li et al. 2022c). The rapid accumulation of MPs in the environment not only alters the structure and processes of ecosystems but also affects their multifunctionality and ecosystem services, potentially increasing the emission of CO2 and CH4 and their global warming potential (Zhou et al. 2023). Although the effects of MPs on individual organisms, biodiversity, and ecosystems have been extensively studied, their contribution to global climate change remains highly debated (Wang et al. 2021a). Recent relevant research has primarily focused on exploring the adverse effects of microplastic pollution on the environment and its potential influence on greenhouse gas emissions. While these studies have found that, under certain experimental conditions, the presence of MPs appears to increase the release of carbon dioxide and methane, these effects vary depending on the ecosystem type, MPs concentration, MPs type, and environmental conditions. Moreover, the current research is predominantly based on pot experiments, where the concentrations of MPs used differ significantly from those found in the natural environment, thus raising concerns about the credibility and applicability of the data. Furthermore, microplastics may have very long residence times in the environment, necessitating more long-term studies to understand their extended impact on greenhouse gas emissions. Research in this regard is still in its early stages. The existing research does not provide a clear understanding of the diversity in the accumulation and impact of MPs in various ecosystems. Incorporating this complexity into research remains a challenge.

The paper reviews recent research findings regarding the impact of MPs on global climate change, discussing the interactions between MPs and climate change and their effects on GHG emissions in different ecosystems. In this study, we conducted a comprehensive bibliometric analysis of research literature related to MPs and climate change/GHG emissions published from 2011 to 2023. We systematically summarized the current status and challenges of MPs’ impact on GHG emissions in marine, terrestrial, and atmospheric ecosystems. Additionally, we explored the potential hazards of MPs in different environments on global climate warming, aiming to provide a theoretical foundation for the study of global climate change from the perspective of MPs pollution.

2 Integrated bibliometric analysis

This study employed VOSviewer (version 1.6.19) to validate the recent dynamics of research involving MPs in the context of the greenhouse effect and climate change. VOSviewer is a software application capable of constructing network diagrams among related content (Zhang et al. 2020b). The software enables the creation, visualization, and exploration of maps using bibliometric network data. The results are displayed in clusters to provide a clear visual representation of the interconnections among bibliometric data (Pauna et al. 2019). The literature utilized in this study was retrieved from the Web of Science database on August 13, 2023. The search input was “microplastic/microplastics” AND “greenhouse/climate change/CO2/CH4/N2O”. The time frame was set to encompass all available publication years in the Web of Science Core Collection database, automatically ranging from 2011 to 2023. After manual screening, 878 references most relevant to the study topic were obtained. Subsequently, these references were inputted into VOSviewer, with a minimum co-occurrence frequency requirement of 10 appearances in the co-occurrence keyword network. After further manual screening, 197 keywords were obtained, based on which co-occurrences were calculated and a network diagram was generated, as shown in Fig. 1.

Fig. 1
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Network map of keyword co-occurrences and evolution of research themes over time

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In Fig. 1, each node represents a keyword, with larger nodes indicating higher total link strength, reflecting stronger associations with other items. Different colors indicate the temporal proximity of research related to the keyword; the darker the red color, the more recent the research. The thickness of the connecting lines between nodes indicates the degree of correlation between keywords, with thicker lines indicating higher relevance. From Fig. 1, it can be observed that research about the relationship between MPs and climate change has been predominantly published after May 2020. During the period between May 2020 and May 2021, articles mainly focused on aspects such as the distribution of MPs in sediments and marine environments. In contrast, articles published after May 2021 predominantly concentrated on research into MPs fragmentation, degradation, and production in environments like soils. Additionally, we observed that polyethylene (PE), polypropylene (PP), and polystyrene (PS) are the among the most popular types of MPs studied in the context of MPs and climate change.

In addition to the three types of plastics, namely “polyethylene”, “polypropylene”, and “polystyrene”, the top ten keywords ranked by total link strength include “soil”, “distribution”, “sediment”, “fragment”, “polymer”, “production”, “characteristic”, “sea”, “fiber”, and “shape”. Table S1 provides some information about these keywords. The Total Link Strength signifies the cumulative strength of connections that the keyword shares with other keywords. Links denote the associations or relationships between two keywords. Occurrences represent the frequency of appearance of the keyword within the 878 most relevant references of this study. These keywords are commonly found in literature exploring the relationship between MPs and climate change, often appearing in conjunction with the term “MPs”.

3 Sources and pollution characteristics of microplastics in the environment

The quantity of plastic waste has dramatically increased in recent years, and research simulations predict that global plastic waste will triple from 2015 to 2060, reaching 270 million tons (Li et al. 2020). The extensive use of plastic coverings in agricultural production to enhance crop yields, coupled with low recycling rates, results in the accumulation of substantial plastic residues in the soil (Qi et al. 2020). Organic fertilizers are considered emerging contributors to MPs accumulation in the soil (O'Connor et al. 2022). The large amount of plastic waste generated on land contributes to the contamination of aquatic environments with MPs (Kumar et al. 2020). Studies have indicated that soil erosion and river transport are significant pathways for plastic to be transported from land to the oceans (Schmidt et al. 2018). Plastic waste has had numerous adverse effects on life on Earth, as it severely damages life due to the accumulation of plastic waste in landfills, soil infiltration, increased GHG emissions, and other factors (Amobonye et al. 2021; Priya et al. 2022).

MPs have a large surface area and hydrophobicity, allowing them to concentrate toxic chemicals such as heavy metals, polycyclic aromatic hydrocarbons, drugs, pesticides, nanoparticles, and organic halogens on their surfaces, serving as the main carriers for the spread of such pollution (Bhagat et al. 2021; Brennecke et al. 2016; Hildebrandt et al. 2020). The additives added by MPs during the production process mainly include acidifiers, lubricants, light stabilizers, heat stabilizers, pigments, antistatic agents, antioxidants, and plasticizers, among others (Sridharan et al. 2022). Most plastic additives do not chemically bond with the polymer matrix, so they can be released from the plastic (Boots et al. 2019; Mishra et al. 2023; Zhang et al. 2020a). As MPs age and decompose, toxic plastic additives can be released into the soil environment, causing harm to the environment. Examples of such additives include widely used Bisphenol A (Machado et al. 2018) and Brominated PS flame retardants (Gulizia et al. 2023), which have been shown to have toxic effects on organisms. The fragmentation of plastics in the environment, combined with the release of chemical additives from these plastics, may lead to an exponential increase in the release of toxic compounds, forming a so-called “toxic debt” (Rillig et al. 2021a).

Generally, the sources of MPs in the environment are diverse, ranging from the production and use of plastic products to improper plastic waste management, all of which can contribute to the presence of MPs in the environment. The characteristics of MPs, such as their resistance to degradation and high affinity for organic pollutants, can potentially have toxic effects on ecosystems and organisms. Therefore, understanding the sources and contamination characteristics of MPs is crucial for implementing effective environmental protection measures and reducing MPs pollution (Fig. 2).

Fig. 2
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Degradation pathways and mechanisms of microplastics in the environment

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4 Mechanisms of microplastics’ impact on greenhouse gas emissions

4.1 Direct impact on greenhouse gas emissions

Plastics are synthetic organic polymers composed primarily of C-C bonds and C-H bonds, with their raw materials primarily coming from fossil fuels, coal, petroleum, and natural gas. Therefore, plastics release a significant amount of CO2 during both natural and anthropogenic degradation processes (Ahmed et al. 2018). In the environment, MPs can be categorized into three main types of degradation mechanisms: physical degradation, chemical degradation, and biodegradation. Physical degradation involves processes such as mechanical fragmentation, temperature fluctuations, pH changes, and exposure to ultraviolet/red light radiation. Chemical degradation includes decomposition induced by ozone and catalytic degradation. Biodegradation, on the other hand, refers to the breakdown of MPs into smaller molecular compounds through the enzymatic action of microorganisms (Lin et al. 2022). MPs are predominantly present in soil and aquatic environments, and they primarily undergo degradation through biological processes (Jeyavani et al. 2021). Certain insects, bacteria, and fungi have been found to consume these polymers and convert them into low molecular weight carbon compounds (Amobonye et al. 2021). Auta et al. (2018) investigated the growth response and degradation mechanisms of two pure bacterial cultures from mangrove sediments on PP-MPs. Fourier-transform infrared spectroscopy and scanning electron microscopy were employed to analyze the structural and morphological changes of PP-MPs after microbial treatment, further confirming the degradation of PP-MPs by environmental microorganisms.

There is limited understanding of the interactions between MPs particles in the environment and the associated microorganisms on their surfaces, as well as their impact on soil carbon pools. The “negative or positive priming hypothesis”, proposed by Rillig et al. (2021b), offers some insight into the effects of exogenous carbon substrate including MPs additions on the mineralization of indigenous soil organic carbon (SOC) and CO2 emissions. This hypothesis suggests that if the addition of substrates promotes the mineralization of existing indigenous soil organic carbon, positive priming occurs; conversely, negative priming occurs if the exogenous carbon substrate inhibits the mineralization of indigenous carbon. During the degradation process, MPs release carbon-containing compounds, which could potentially elevate the levels of dissolved organic matter (DOM) in soil. This, in turn, could alter the composition of the soil carbon pool and enhance the potential for soil to release GHG such as carbon CO2 (Liu et al. 2017). Traditional MPs tend to exhibit reduced priming effects due to their stability and resistance to degradation (Lin and Su 2022). Chen et al. (2022d) found that the pristine MPs increased DOM humification and promoted the formation of larger molecular weight components, thereby reducing DOM bioavailability by approximately 16% to 23%, and inducing a negative priming effect. Yu et al. (2021) discovered that MPs inhibit the degradation of native organic matter. In soils contaminated with MPs, the mineral-associated SOC content increased by 52.5%, while the microbially available SOC content decreased by 18.9%.

Biodegradable plastics are more commonly used domestically and in agriculture to minimize plastic pollution as they exhibit biodegradable properties (Pratt et al. 2020). However, soils contaminated with biodegradable plastics may emit more CO2 (Greenfield et al. 2022). The “positive priming” hypothesis can explain how biodegradable plastics accelerate the decomposition of organic carbon in the soil carbon pool by providing a labile carbon source for microbial acitivity (Zhang et al. 2022d). Sanz-Lazaro et al. (2021) observed that biodegradable plastics can stimulate the decomposition of carbon in marine sediments. If biodegradable plastics become a major component of marine pollution, the biogeochemical cycling of carbon and nutrients in sediments may be significantly affected, potentially impacting the carbon sequestration in coastal ecosystems and compromising their ability to respond to climate change.

When exposed to the natural environment, MPs often undergo gradual colonization by microbial biofilms on their surfaces, resulting in the formation of a phenomenon termed the “plastisphere” (Zhai et al. 2023). The plastisphere encompasses microorganisms such as bacteria, algae, and fungi, which attach to the surface of MPs, forming intricate ecosystems (Wright et al. 2020). Microorganisms within the plastisphere can decompose the organic substances present on the surface of MPs, facilitating the degradation of MPs. However, this degradation process may also lead to the liberation of MPs fragments, consequently augmenting the overall quantity of MPs in the environment (Sooriyakumar et al. 2022). Simultaneously, within the biofilms formed on the surfaces of MPs, microbial metabolic activities may prompt the release and degradation of organic carbon, subsequently converting it into biomass and CO2 (Catania et al. 2020; Cornejo-D'Ottone et al. 2020). Research on the generation of GHG during the degradation process of MPs is still in its infancy. Further exploration of the MPs degradation mechanisms, microbial activities, as well as field monitoring and experiments are needed to develop more targeted measures for reducing GHG emissions and protecting the environment (Table 1).

Table 1 Degradation of microplastics produces greenhouse gases
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4.2 Indirect impacts on greenhouse gas emissions

MPs affect carbon sources, CO2 emissions, and carbon transformation processes, primarily by influencing plant and animal activities, altering gene abundance, enzyme activity, microbial community composition and soil structure (Rillig et al. 2021b). This can greatly alter carbon allocation in the plant-soil system, which also has significant implications for the downstream cycling of other macronutrients such as nitrogen (N) and phosphorus (P) (Zang et al. 2020). Numerous studies have demonstrated that the addition of MPs significantly promotes soil CO2 emissions. Gao et al. (2021) found that 18% of MPs in the soil can increase soil CO2 emission flux by 28.67%, and CO2 emissions are significantly positively correlated with microorganisms tolerant to MPs, such as Bacillus, Pseudomonas, and Arthrobacter. Polyacrylamide (PA) accelerates soil carbon sequestration by enhancing the abundance of accA and pccA genes, and it facilitates the degradation of organic carbon and CH4 metabolism by altering the abundance of MNP, CHIA, mcrA, pmoA, and mmoX gene, i.e., “positive priming” (Li et al. 2023c). On the other hand, the “negative priming” hypothesis speculates that when exogenously added organic carbon (MPs) is more easily accessible than natural SOC, microorganisms preferentially allocate resources to utilize the substrate, thus reducing SOC mineralization (Yang et al. 2023). Under the influence of MPs in the environment, microorganisms experience stress during metabolic processes, requiring more substrates and energy. The microbial stress resulting from environmental contamination can lead to a decrease in carbon-use efficiency by microbes, thereby resulting in poor carbon assimilation and greater CO2 release (Xu et al. 2019). This may explain why the observed dose of MPs induces an increase in CO2 emissions (Zhang et al. 2022e).

Nitrogen cycling is an essential component of the global biogeochemical cycles, and the main processes involved in nitrogen cycling in ecosystems are ammonification, nitrification, and denitrification (Dai et al. 2020). MPs profoundly influence nitrogen cycling from genes to metabolic processes. They can affect nitrogen sources, nitrogen fixation, ammonification, nitrification, and denitrification processes, which in turn impact N2O emissions by stimulating enzyme activity and altering microbial community structure and composition (Wang et al. 2022b). MPs pollution can result in an augmentation of soil organic carbon content, altering the soil’s C:N ratio, leading to an increase in the abundance of nitrogen-fixing bacteria, ultimately causing a rise in soil nitrogen content, such as PVC and PE (Chia et al. 2022). With increasing MP content in the soil, nitrate nitrogen and the ratios of fungi: bacteria, total iso-branched fatty acids: total anteiso-branched fatty acids, and cyclopropyl: precursor significantly decreased (Shi et al. 2022). N2O flux (water-to-air interface) is significantly negatively correlated with nosZl, napA, narG, and nirS, indicating that nitrification and denitrification interactions are the main influencing factors of N2O emissions. Differences in the niche of nirS and nirK denitrifiers may contribute to different N2O emissions. In soils with MPs, nirK denitrifiers may be the main driving factor in the NO2− → NO process (Huang et al. 2019). Moreover, the abundance of MPs in surface water is significantly correlated with nitrification and denitrification processes (Li et al. 2022a). Table 2 summarizes the effects of different types and concentrations of MPs on the microorganisms related to GHG emissions in the environment.

Table 2 Microplastics influence greenhouse gases emission by affecting microorganism
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4.3 Microplastics influence plant physiological metabolism and photosynthesis

The interaction between plastic particles and plants can induce oxidative stress responses in plant cells, negatively affecting photosynthesis, metabolism, gene expression, and other growth parameters (Dad et al. 2023). This can reduce plants’ efficiency in sequestering and utilizing atmospheric CO2, thereby indirectly impacting the global carbon cycle and exacerbating global greenhouse effects (Chen et al. 2022b; Karalija et al. 2022). Research has revealed that MPs can lower the maximum photochemical efficiency of photosystem II (F-v/F-m) and inhibit the synthesis of chlorophyll a, thus affecting plants’ utilization of atmospheric carbon (Liu et al. 2021). The phytotoxicity of MPs depends on the characteristics of plastic particles (exposure dosage, size, shape, type, age, and surface charge) and plants (species, tissues, and growth stages) (Chen et al. 2022b).

Microalgae are one of the most important primary producers in aquatic ecosystems and are susceptible to contamination by MPs, which can have significant impacts on the aquatic food web. Larger MPs can adversely affect microalgae by obstructing light transmission and disrupting photosynthesis, while smaller MPs can disrupt cell walls by adsorbing onto the surface of algae (Liu et al. 2020a). MPs can induce growth inhibition in microalgae, increase oxidative damage, decrease concentrations of photosynthetic pigments, cause cellular vacuolation, and increase the number and volume of vacuoles. The toxicity of MPs, when combined with heavy metal exposure, is even greater and can affect metabolism-related pathways, leading to inhibition of algal metabolism and exacerbation of toxicity (Liao et al. 2020). MPs may also disrupt the regulatory mechanisms of algal populations in water bodies by reducing the availability or uptake of nutrients (bottom-up) or reducing the number of predator species (top-down) (Prata et al. 2019a, 2019b). In certain aquatic ecosystems, such as blue carbon ecosystems, the presence of submerged vegetation leads to a reduction in water flow velocity due to interception. Consequently, this diminished flow velocity can result in the aggregation of microplastic particles. This phenomenon has the potential to impart adverse effects on the growth of plants within these ecologically sensitive systems, consequently influencing the carbon sequestration capacity of these ecosystems (Huang et al. 2021).

MPs can be internalized by vascular plants, leading to various phytotoxic effects (Yin et al. 2021). The absorption and translocation of MPs by vascular plants can delay seed germination, hinder plant growth, inhibit photosynthesis, disrupt nutrient metabolism, cause oxidative damage, and induce genetic toxicity (Dong et al. 2022). MPs can be taken up by plant roots and then transferred to other tissues through transpiration pull. They can suppress root activity and pyrophosphate ribose carboxylase activity to inhibit biomass accumulation (Liu et al. 2022a). MPs induce oxidative bursts in plant tissues by causing mechanical damage and disrupting the tertiary structure of antioxidant enzymes (Dong et al. 2020) and they also inhibit the biosynthesis of jasmonic acid and lignin (Zhou et al. 2021). MPs inhibit photosynthesis by modulating both non-stomatal and stomatal factors in leaves (Yang and Gao 2022). The toxicity of MPs to plants is illustrated in Fig. 3. The interactions between MPs and plants are presented in Table 3.

Fig. 3
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The toxic effects of microplastics on plants linked to reduced photosynthetic activity and CO2 sequestration potential

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Table 3 The effects of microplastics on the photosynthetic system of plants
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5 The impact of microplastics on the global greenhouse effect in different ecosystems

5.1 The impact of microplastics on the global greenhouse effect in marine ecosystems

Currently, the ocean stores approximately 3.8 × 10^16 metric tons of carbon (equivalent to around 1.4 × 10^17 metric tons of CO2), absorbing approximately 24% of global CO2 emissions (Renforth and Henderson 2017). However, the extensive plastic pollution present in the ocean can have detrimental effects on gas exchange and marine carbon cycling, leading to increased GHG emissions from marine ecosystems and ultimately exerting adverse impacts on global warming and climate change (Mahmoudnia 2023). Over the past two decades, marine pollution caused by plastic debris has been steadily increasing, greatly exacerbating global climate change (Sharma et al. 2023). The combination of floating MPs with other pollutants in the ocean can result in more severe consequences. For instance, MPs can form MP-Oil aggregates when combined with petroleum, which has more pronounced effects on phytoplankton, zooplankton, and high-nutrient species in the marine environment compared to the individual impacts of MPs or oil alone (Yang et al. 2022b).

A study has revealed that approximately 54.5% of the MPs floating in the ocean are composed of PE, while 16.5% are made of PP. The remaining portion includes PVC, PS, polyethylene terephthalate, and PA, among others. Due to their lower density, PE and PP tend to float on the water surface, thereby affecting the ocean’s surface. Conversely, MPs with higher density, such as PVC, impact seafloor sediments (Issac and Kandasubramanian 2021). Additionally, due to biological contamination, MPs can also sink to the seafloor, where microorganisms form biofilms on small MPs, increasing their material density and causing vertical migration (Kooi et al. 2017). Plastics in the ocean undergo mechanical and photochemical fragmentation processes accelerated by factors like waves and sunlight, resulting in the formation of MP particles. UV radiation induces the photodegradation of MPs, leading to the gradual release of soluble organic carbon and, to a lesser extent, the leaching of CO2, carbon monoxide, CH4, and other hydrocarbon gases (Ding et al. 2022b). Research indicates that UV radiation has already degraded 7% to 22% of all floating plastics released into the ocean (Delre et al. 2023).

The sea surface microlayer serves as the oceanic boundary layer that controls the exchange of atmospheric gases. Organic compounds produced by organisms can accumulate in this layer. MPs increase the production and enrichment of carbohydrate-like and proteinaceous gel-like compounds in the sea-surface microlayer, thereby, directly and indirectly, influencing the absorption of CO2 in the ocean carbon cycle (Galgani et al. 2023). Marine plastics can affect the photosynthesis and growth of phytoplankton, impact the marine biological pump, influence the storage of oceanic carbon, and affect the gas exchange and cycling of CO2 in the ocean, potentially impacting GHG emissions (Shen et al. 2020). Furthermore, marine microalgae, influenced by MPs, release Volatile Halocarbons as a protective mechanism to prevent oxidative stress and the toxic effects caused by MPs. However, Volatile Halocarbons are trace GHG that can contribute to ozone layer depletion (Lang et al. 2022). The impact of MPs on GHG emissions in the ocean is shown in Fig. 4.

Fig. 4
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The impact of microplastics on marine ecosystems

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5.2 The impact of microplastics on the global greenhouse effect in terrestrial ecosystems

According to estimates, the concentration of MPs in terrestrial ecosystems may even surpass the number of MPs entering the marine ecosystem (Yang et al. 2022a). Once MPs enter the terrestrial ecosystem, they have the potential to affect the assessment of soil carbon storage and GHG fluxes (Chen et al. 2022e). Plastic particles have the potential to stimulate the decomposition of SOC (i.e., priming effect), and the accumulation of MPs in terrestrial ecosystems can impact GHG production by altering soil structure and microbial functionality (Yu et al. 2022). Soil contaminated with MPs can affect soil physical properties, and once they enter the terrestrial ecosystem, MPs can impact the sequestration of carbon and nitrogen by altering soil properties such as pH, soil aggregate stability, and soil porosity, thereby compromising the sustainability of the soil system (Ingraffia et al. 2022). MPs in soil can also directly impact plants or the physical and microbial metabolic environment of the soil, indirectly affecting plant growth, and altering the quantity and quality of soil carbon and nitrogen inputs through changes in plant litter and root systems (Yao et al. 2022). Some studies indicate that the accumulation of MPs in terrestrial ecosystems can significantly increase the abundance of microbial functional genes encoding enzymes involved in cellulose and lignin degradation, thereby stimulating the potential decomposition of SOC (Yu et al. 2022).

MPs in rivers and lakes may be able to affect greenhouse gas emissions in various ways. In the river, the MPS can hinder the thermal adaptation of microbial communities, decrease species interactions and community complexity, and enhance CO2 release from the microbial community, and under heatwave conditions, MPs can also diminish microbial preference for stable carbon and reduce community carbon metabolism capacity (Wang et al. 2023b). Due to the resistance of MPs to microbial decomposition in water bodies, a significant accumulation of MPs occurs in benthic sediments, where they undergo anaerobic degradation by microorganisms and release substantial amounts of CH4 into the atmosphere (Kumar et al. 2022). The riparian zone serves as a central hub for MPs, and their accumulation alters the functioning of this zone (e.g., carbon storage and ammonium removal from rivers), posing a significant threat to river ecosystems (Chen et al. 2022d). MPs accumulation reduces ammonium removal in sediments by 8.2% to 12.8%, primarily due to a decrease in the abundance of nitrifiers (Nitrososphaera and Nitrososphaeraceae) and genes encoding ammonium and hydroxylamine oxidation (amoA, amoB, amoC, and hao) caused by MPs accumulation. Moreover, the substrate and gene abundance related to the hydroxylamine oxidation process are reduced by MPs accumulation, resulting in a decrease in N2O emissions by 16.3% to 34.3% (Chen et al. 2022c). Currently, research on the relationship between MPs and GHG emissions primarily focuses on soil aspects, where many studies have found that MPs contamination directly contributes to climate change by accelerating GHG emissions from soil to the atmosphere, as well as indirectly impacting climate change by promoting soil respiration and negatively affecting natural carbon sinks such as trees (Chia et al. 2023). The impact of MPs on soil GHG emissions is illustrated in Fig. 5.

Fig. 5
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The impact of microplastics on soil greenhouse gas emissions

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5.3 The impact of microplastics on the global greenhouse effect in atmospheric ecosystems

One key reason for the worldwide dissemination of MPs is their atmospheric dispersion and transport. Due to their small size and relatively low density, MPs are easily carried by the wind and can persist in the atmosphere for extended periods, reaching remote ecosystems and posing significant long-term threats to these fragile ecosystems (Liu et al. 2019a). Suspended atmospheric MPs are widely present in the atmosphere, and can be detected in urban areas, suburbs, and remote regions far from the sources of MPs (Zhang et al. 2020c). Even in the marine atmosphere far from the coast, MPs particles have been found (Trainic et al. 2020), indicating that the potential long-distance transboundary atmospheric transport of MPs is gradually becoming a significant environmental pollution source in the atmosphere (Zhang et al. 2023a). Atmospheric MPs are more transient and transportable than those found in aquatic environments (Bao et al. 2023). Additionally, numerous studies have found that coarser dust particles in the air can induce a warming effect. MPs in the atmosphere affect the Earth’s climate through the absorption and scattering of radiation (direct radiative effects) (Chen et al. 2021). As a result, their continued production could have increasingly significant impacts on future climate systems (Revell et al. 2021).

MPs in the air can be transported over long distances and accumulate in various terrestrial and aquatic environments (Mbachu et al. 2020). The distribution of atmospheric MPs is not only influenced by weather conditions but also potentially related to their sources (Liu et al. 2020d), The main sources of atmospheric MPs include textiles, human activities, and the fragmentation of large plastics (Can-Guven 2021). Atmospheric transport is an important pathway for land-based MPs to be transported to remote areas (Liu et al. 2020c). The correlation coefficient between the characteristics of MPs in the atmosphere and surface seawater tends to increase with increasing proximity to the coastline (Ding et al. 2022a). Currently, bubble bursting is considered an important pathway for MPs to transition from the sea surface to the atmosphere (Masry et al. 2021). Water components (such as high salinity, gel concentration, and viscosity) can regulate the aggregation of plastic gels and subsequent transportation from water to air (Wang et al. 2021c). The mechanisms involved may be closely related to the formation of plastic gel through cationic bridging, thereby enhancing the ejection of plastic gels into the air (Cunliffe et al. 2013; Huang et al. 2020; Shiu et al. 2022).

The primary non-biological degradation process of plastics is initiated by light-induced oxidation. When MPs are directly exposed to sunlight in the atmosphere, it leads to the fragmentation of polymer chains, resulting in the formation of polymer fragments and volatile compounds (Gewert et al. 2015). During the degradation process of MPs, numerous organic compounds are released, ranging from short-chain carboxylic acids to aromatic and aliphatic compounds with different functional groups. These compounds have a significant potential impact on the composition and concentration of the carbon reservoir in the atmosphere. The reactive species formed within the polymer during this process may not only react with oxygen but also with other compounds such as nitrogen oxides (Bianco and Passananti 2020). Wu et al. (2022) observed that following exposure to ultraviolet radiation, PS-MPs exhibited negligible alterations in their physicochemical attributes. Nevertheless, this exposure led to the liberation of numerous toxic compounds such as benzene, toluene, and phenol. Furthermore, these compounds are often subject to subsequent degradation, ultimately transforming into inorganic compounds including CO2. This cascade of events has the potential to exacerbate the greenhouse effect. Vicente et al. (2009) found that the rate of oxidative degradation through photodegradation of MPs depends on radiation energy, the concentration of O2 and H2O in the mixed gas, as well as particle diameter.

Several studies suggest that the presence of MPs may potentially catalyze ozone generation or degradation processes. Due to ozone’s robust oxidative nature, it can interact with MPs, expediting their aging process (Zhang et al. 2022c). As a result of extended exposure to the atmosphere, MPs could engage in chemical reactions with upper atmospheric ozone, resulting in the depletion of high-altitude ozone. Notably, Zhao and You (2022) have ascertained that atmospheric MPs, during the course of photodegradation, yield photochemical ozone, contributing to what is termed “ozone pollution”, which could engender climate change and air pollution. Ozone plays a pivotal role in the Earth’s troposphere, participating in atmospheric temperature regulation (Bornman et al. 2019). The impact of MPs on ozone generation and decomposition might disturb this equilibrium, consequently influencing the energy transfer within the atmosphere and the greenhouse effect. Furthermore, MPs, especially in the form of nanoplastics could act as cloud condensation nuclei or ice-nucleating particles, affecting cloud formation processes. In sufficient quantities, they could change the cloud albedo, precipitation, and cloud lifetime, collectively impacting the Earth’s radiation balance and climate (Aeschlimann et al. 2022). Following an extended period of residence in the atmosphere, MPs could deposit onto plant leaves through meteorological processes like precipitation. This deposition could subsequently undermine plant growth rates and photosynthetic efficiency, ultimately impacting plants’ capacity to sequester CO2 through photosynthesis (Gan et al. 2023; Liu et al. 2020b).

Currently, the majority of research indicates that MPs in the environment can contribute to the emission of GHG through various pathways. While some studies have found that MPs can reduce GHG production in the short term, they significantly impact the carbon pool in the environment, increasing the potential for GHG emissions. Yu et al. (2021) observed that the addition of MPs can decrease the mineralization and decomposition of SOC in the short term, thus reducing soil CO2 and N2O emissions. However, due to the carbon-rich and relatively stable nature of MPs, they are not easily utilized by microorganisms, leading to a significant increase in mineral-associated SOC content. The increase in soil SOC content contributes to enhanced potential for GHG emissions from the soil (Dou et al. 2016). This phenomenon may be explained by the “organic-organic persistence hypothesis” proposed by Rillig et al. (2021b). This hypothesis suggests that the high surface area of MPs facilitates the adsorption of DOC in the environment, thereby limiting the utilization of unstable carbon components by CH4-producing bacteria and suppressing CH4 production. According to this hypothesis, although MPs inhibit CH4 emissions in the short term, they do not alter the soil carbon pool, and therefore, do not reduce the potential for soil GHG emissions. The impact of MPs on GHG emissions varies under different environmental conditions (Table 4), depending on the characteristics of MPs, environmental factors, and climate conditions. Therefore, comprehensive measures need to be implemented to reduce the generation and impact of MPs.

Table 4 The impact of microplastics on greenhouse gas emissions
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6 Nexus between microplastics pollution and climate change

Climate change is a significant global threat that has already impacted every region worldwide, manifesting in elevated ocean temperatures, rising sea levels, ocean acidification, and intensity and frequency of extreme weather events including drought, flood, and wildfire. These occurrences are giving rise to extensive ecological and socio-economic damages, with the expectation of potential exacerbation in the future, leading to heightened frequency and increased severity of ecological disasters (Vicedo-Cabrera et al. 2021; Vitousek et al. 2017). Currently, MPs pollution is influenced by climate and is expected to further spread as climate-driven extreme weather events such as floods increase in intensity and frequency. Previously, remote and vulnerable environments distant from human society were minimally affected by anthropogenic pressures, but they are now facing an inevitable threat of climate change-induced plastic pollution (Ford et al. 2022). Unique and fragile ecosystems, such as polar regions, which were previously distant from human society and minimally affected by anthropogenic pressures, have been found to contain significant amounts of MPs in recent years, especially within the sea ice (Mishra et al. 2021). The light-absorbing properties of MPs may also contribute to accelerated warming and melting of the polar ice caps. Additionally, the melting of sea ice affects the salinity, temperature, and density of polar oceans, all of which influence the density of seawater and the potential aggregation and dispersion of plastic particles (Koelmans et al. 2015; Rowlands et al. 2021). Therefore, MPs pollution and global warming may mutually reinforce each other, ultimately leading to more severe consequences (Evangeliou et al. 2020).

Climate change has increased the amount of plastic entering lakes and has also increased the frequency and intensity of sediment resuspension. The synergistic effect of sediment resuspension and MPs will accelerate eutrophication and introduce more pollutants, especially organic contaminants, into the food chain. Therefore, climate change exacerbates MPs pollution and sediment resuspension in eutrophic lakes, while the presence of MPs and resuspension events further intensify these two environmental impacts (Zhang et al. 2020d). Wang et al. (2023a) observed that the enhanced greenhouse effect amplifies the competitive advantage of MPs-derived DOM. Both the greenhouse effect and MPs pollution diminish microbial utilization of ambient DOM in the natural environment, prompting a shift towards more easily accessible carbon sources, such as DOM originating from MPs reservoirs. This shift aims to enhance growth efficiency and facilitate the microbial community in adopting a K-strategy to effectively exploit recalcitrant carbon. Research has indicated that specific weather conditions, such as precipitation, contribute to the further transport and dispersion of MPs, entering rivers, lakes, and oceans through stormwater outfalls (Li et al. 2020). For instance, after being struck by a typhoon, the abundance of MPs in the seawater and sediments of Sangou Bay in China increased by as much as 40% (Wang et al. 2019). Moreover, studies suggest that global climate warming leads to the loss of marine dissolved oxygen, while MPs pollution affects the grazing of zooplankton on microphytoplankton, further exacerbating the trend of marine oxygen depletion (Kvale et al. 2021), leading to GHG emission. Global warming has significant catastrophic consequences for the global environment, and plastic pollution is exacerbating this impact (Ford et al. 2022).

Currently, plastic pollution and global climate change are often regarded as separate issues, and research on climate change and MPs pollution is typically conducted independently. However, considering the global climate change issue in conjunction with MPs pollution in certain aspects and unraveling the nexus between these two environmental issues may help identify solutions to address both climate change and MPs pollution. Numerous controlled experiments in laboratories have found that while exploring solutions to MPs pollution, methods that contribute to mitigating GHG emissions have also been revealed. For instance, Li et al. (2022b) observed that the co-occurrence of MPs and biochar resulted in a reduction in soil CO2 emissions compared to the individual application of biochar or PE-MPs pollution. Furthermore, this co-presence exhibited an antagonistic effect on the subsequent global warming potential impacts. Generally, MPs increase the emissions of GHG in the environment, but research has also shown that in soil, MPs may reduce N2O emissions (Ren et al. 2020). Transforming plastic effectively into fuel also provides hope for mitigating environmental pollution and addressing the energy crisis (Kumar et al. 2023; Ye et al. 2022). Photocatalysis and microbial degradation technologies have demonstrated prospects at the laboratory scale for converting MPs into water-soluble hydrocarbons, CO2, and in limited cases, into useful fuels (Ebrahimbabaie et al. 2022). These findings indicate that the impact of MPs on GHG emissions can be regulated by creating specific conditions, thus reducing the contribution of MPs in the environment to global climate change.

7 Conclusions

MPs not only pose a significant pollution problem to the environment but also have the potential to contribute to GHG emissions and climate change to some extent. This review provides a comprehensive overview of the current research on the impact of MPs pollution on global greenhouse effects, including the influence of MPs on GHG emissions in marine, terrestrial, and atmospheric ecosystems, while also providing recommendations for prospective research avenues. It is worth noting that MPs are synthetic organic polymers consisting entirely of C-C bonds and C-H bonds, which not only directly release GHG such as CO2 and CH4 during degradation but also impact the relative abundance of C and N cycling-related microorganisms in the environment, impacting the emissions of CO2, CH4, and N2O, among other GHG. Furthermore, the interaction between MPs and plants induces oxidative stress in plant cells, negatively affecting photosynthesis, metabolism, gene expression, and other growth parameters, thereby reducing plants’ photosynthetic efficiency in sequestering and utilizing atmospheric CO2 and indirectly influencing global carbon cycling, exacerbating the global greenhouse effect.

However, these studies mainly obtained data in pot experiments, and these controlled experiments often add more MPs to make it easier to observe noticeable differences. In fact, the number of MPs in natural ecosystems is significantly lower than the amount added in the experiment. This inconsistency raises potential concerns about the reliability of the conclusions and overstatement of the effects of MPs. Therefore, this paper advocates that researchers should try to use the number of MPs present in the actual environment to conduct experiments, rather than artificially increasing the number of MPs added. In addition, some statistical models can be used to estimate the actual impact of MPs, or some correction experiments can be conducted to more accurately reflect the actual situation.

This study found that there are many challenges and uncertainties in the current quantitative analysis techniques for MPs, which can lead to biases in the analysis of the impact of MPs on the environment, especially ecosystems. This uncertainty makes obtaining reliable data a challenging task. To address this issue, researchers can adopt a variety of strategies, including optimizing analytical methods, improving standardization of sample handling, and conducting comprehensive field observations and long-term studies to more fully assess the distribution and effects of MPs.

Lastly, this article emphasizes the significant impacts of MPs from various sources on GHG emissions and calls for further research on the effects of MPs on ecosystems and global climate change. This necessitates global collaboration and the implementation of effective mitigation strategies to address the increasingly severe issue of MPs pollution and protect ecosystems and human health.

8 Future research

In recent years, there has been a growing scholarly interest in the association between MPs and global greenhouse gas emissions and climate change. While the scientific community has gained preliminary insights into the adverse environmental impacts of MPs, there is an urgent need for more in-depth research to thoroughly explore the intricate relationship between MPs, greenhouse gas emissions, and climate change. Of particular note is the emphasis on the following areas in future research:

  1. (1)

    Future research directions should also focus on the weathering-induced aging and degradation processes of MPs and their impact on GHG emissions. It is necessary to investigate the microbial interactions of MPs at a more microscopic level, such as biofilm formation and the consequent “plastisphere,” and their impact on degradation and greenhouse gas emissions.

  2. (2)

    MPs can impact biodiversity, energy flow, and nutrient cycling in ecosystems. Future research needs to consider the synergistic effects of different types and sizes of MPs, as well as the interactions between MPs and other pollutants, on GHG emissions.

  3. (3)

    Our understanding of the long-term behavior and interactions of MPs in terrestrial and aquatic ecosystems remains significantly limited. To delve deeper into this, researchers need to conduct field observations and laboratory studies for a comprehensive assessment of the potential impacts of MPs on ecosystem functionality. Based on these findings, effective monitoring and management strategies should be formulated. These measures will contribute to a better comprehension of the behavior of MPs in natural environments and the mitigation of their potential ecological risks.

  4. (4)

    Currently, our knowledge of the long-term behavior and interactions of MPs in ecosystems is still limited, especially regarding the role of the atmosphere as an important transport pathway for MPs. There is a considerable lack of research on MPs in atmospheric ecosystems. Therefore, future studies should delve into the profound exploration of the impact of atmospheric MPs on climate processes, such as radiative forcing and cloud formation. Additionally, attention should be directed toward investigating the potential health risks posed by the inhalation of MPs and their associated chemical components.

  5. (5)

    Currently, some studies have already focused on the development and application of biodegradable plastics. However, to prevent secondary pollution, it is imperative to conduct a systematic risk analysis of biodegradable plastics. This analysis should include the assessment of whether biodegradable plastics can completely degrade. In cases where complete degradation is not achieved, the generation of micro/nano plastics may, in fact, pose more severe risks. Consequently, it is essential to strengthen the safety evaluation of the degradation products of biodegradable plastics to ensure that the degradation process does not produce environmentally or biologically harmful substances.

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    The interaction between plastics and climate is a pressing global concern. Strengthening research on this interaction will help us comprehend the role of plastics in climate change and offer scientific evidence for policy formulation and management. Global cooperation and interdisciplinary efforts are vital to tackle plastic pollution and climate change. The international community should collaborate, undertake joint research projects, and exchange experiences and best practices.