Plastic pollution involves the buildup of synthetic plastic products in the environment, from large items to microscopic fragments. Climate change refers to long-term shifts in global weather patterns, primarily driven by elevated greenhouse gas concentrations. These two environmental challenges are closely linked, intensifying each other’s effects and creating a complex, interconnected global problem.
Greenhouse Gas Emissions from Plastic Production
Plastic production, from raw material extraction to final product, releases substantial greenhouse gases. Most plastics begin as fossil fuels like oil and natural gas. Extracting and processing these resources demands significant energy, often from burning more fossil fuels, which directly increases atmospheric carbon dioxide and methane levels.
These extracted fossil fuels undergo complex chemical transformations. Refineries convert crude oil and natural gas into simpler hydrocarbon building blocks like ethylene and propylene. These blocks are then polymerized in chemical plants to form long chains, creating various plastic polymers such as polyethylene, polypropylene, and polyvinyl chloride.
Polymerization and manufacturing are energy-intensive, requiring high temperatures and pressures. This demands large amounts of power, typically from fossil fuels, contributing to greenhouse gas emissions. Unintentional leaks of gases like methane, known as fugitive emissions, also occur throughout the extraction, processing, and manufacturing chain, increasing the overall greenhouse gas footprint. For example, in 2015, global emissions from ethylene production alone were comparable to those from 45 million passenger vehicles.
Climate Impacts of Plastic Waste Management
The disposal and management of plastic waste also contribute to climate change. Incineration, a common method, releases carbon dioxide and other air pollutants into the atmosphere. Burning one metric ton of plastic can result in almost one ton of CO2 emissions. Globally, burning plastic packaging alone adds approximately 16 million metric tons of greenhouse gases, equivalent to the electricity use of over 2.7 million homes.
Landfills are another significant component of plastic waste management, where some plastics can break down over extended periods, potentially releasing methane. While organic waste primarily contributes to landfill methane emissions, plastic materials can also release methane and ethylene when exposed to sunlight. Methane is a potent greenhouse gas, estimated to be 28 times more effective than CO2 at trapping heat over a 100-year period. The waste sector, including landfills, is responsible for about 20% of human-driven methane emissions globally.
The collection and transport of waste also require energy, typically from fossil fuels, adding to the overall carbon footprint. Even recycling, while generally reducing emissions compared to virgin plastic production, still involves energy consumption and associated greenhouse gas releases. Most plastics are not infinitely recyclable, meaning even recycled plastics may eventually end up in landfills or incinerators, continuing their contribution to greenhouse gas emissions.
Plastic’s Influence on Carbon Sinks
Plastic pollution, especially in marine environments, can disrupt natural processes that absorb atmospheric carbon, known as carbon sinks. The ocean serves as the Earth’s largest carbon reservoir, regulating climate by transferring atmospheric CO2 into its depths through the biological carbon pump. This pump involves atmospheric CO2 dissolving into surface seawater, followed by its incorporation into phytoplankton through photosynthesis.
Phytoplankton, microscopic marine organisms, play a fundamental role in absorbing carbon dioxide. Microplastic pollution can interfere with this process by attaching to phytoplankton surfaces, obstructing light and CO2 absorption. This interference can reduce carbon fixation rates by up to 45% and impair cellular functions necessary for their growth and reproduction. When phytoplankton are consumed by zooplankton, carbon-rich fecal pellets are created which then sink to the ocean floor, facilitating long-term carbon sequestration.
The presence of microplastics can affect zooplankton’s grazing on phytoplankton and reduce the downward flow of sequestrated carbon to the ocean floor when fecal pellets are contaminated. This disruption in the biological carbon pump can lead to a reduced oceanic capacity to sequester carbon, ultimately allowing more CO2 to remain in the atmosphere. Beyond marine environments, microplastics in soil may also alter microbial communities and affect terrestrial carbon cycles, though the full extent of this impact requires further study.