Synthesizing the latest peer-reviewed scientific research, the report systematically maps out three pathways through which plastics affect the climate. Plastics emit greenhouse gases throughout their lifecycle, disrupt key ecosystem processes essential to sequestering carbon, and affect how the Earth reflects and absorbs energy.
Key findings about the state of scientific knowledge on the plastics-climate nexus include the following:
- Greenhouse Gas Emissions: Current estimates do not fully account for the greenhouse gases emitted by plastics during their entire lifecycle. From raw material extraction and manufacturing to transportation, use, and disposal, plastics generate greenhouse gas emissions. Primary production (including fossil fuel extraction and creation of monomers or the building blocks of plastics) is the most emissions-intensive stage of the lifecycle, and incineration of plastic waste and certain forms of chemical recycling can also be emissions-intensive.
- Current data indicate that plastics are responsible for approximately 4% of global greenhouse gas emissions, making the plastics sector at least the world’s fifth-largest emitter if it were a country.
- Current emissions are undercounted due to data gaps. With plastic production expected to triple by 2060, emissions are projected to rise considerably.
- Disruption of the Carbon Cycle: Plastic pollution, including microplastics and nanoplastics, can interfere with the planet’s natural systems that absorb and store carbon, including in soils, plants, and the ocean. Plastics potentially reduce the ocean’s carbon-absorbing ability, increase the release of carbon dioxide from soils, and harm microscopic marine plants vital for carbon storage. While some studies have conflicting results, studies generally find that plastics impact the carbon cycle in ways that contribute to additional warming.
- Impact on Earth’s Radiation Budget: By changing surface reflectivity (albedo) and interacting with clouds and atmospheric energy exchange, plastics can physically alter how the planet reflects and absorbs energy, with possible implications for Earth’s surface temperature. While this is a new and less understood area of research, the limited number of studies that have been done suggest that plastic particles in the atmosphere and on the Earth’s surface might have somewhat of a cooling effect, but much remains unknown.
The clearest finding from the systematic review of the scientific literature is that the body of evidence regarding the impact of plastics on the climate is woefully incomplete, making it impossible, at present, to fully quantify the total climate impact of plastics.
The report stresses that only by enhancing understanding of and rigorously accounting for the ways the global plastics and climate challenges are intertwined will it be possible to address them both effectively.
The report outlines a roadmap for future research to address existing knowledge gaps and fully account for all the climate impacts of plastics. These include:
- More estimates of GHG emissions and emissions intensities across all plastics lifecycle stages (especially for transportation, consumption/use, and unmanaged waste) and for different polymer types.
- More global and national-level GHG emissions and intensity data, particularly since national-level studies have only been done on 14 countries.
- Further investigation into the impacts of plastics on terrestrial, marine, and coastal blue carbon ecosystems, especially on the more understudied carbon sink factors (e.g., the biological carbon pump, marine bacteria, carbon dioxide drawdown into surface waters).
- More experimental and modeling efforts to understand the radiative impacts of plastics, including their influence on clouds, albedo, and ice melt.
The report also calls for this future research utilize realistic mixtures of plastic types, shapes, and weathered states that reflect what is found in the environment, and to report results with greater specificity and standardization to enable data comparability. In addition, as bioplastics production increases, their climate impacts must be studied with the same rigor as conventional plastics.
Recommendations include the following:
- Recommendations for the Public Sector Internationally:
- The Intergovernmental Panel on Climate Change (IPCC) should explicitly include allowance for plastics’ full climate impacts in its assessment reports, emissions scenarios, and models.
- The IPCC should produce a Special Report on Plastics, Petrochemicals, and Climate Change.
- The forthcoming UN Plastics Treaty negotiations should incorporate climate impacts into environmental impact assessments and reporting requirements.
- Recommendations for the Public Sector Nationally and Subnationally:
- Governments should provide financial and other support for research on the plastics-climate nexus and integrate plastics’ climate impacts into GHG emissions inventories, climate vulnerability assessments, and nationally determined contribution (NDC) submissions under the Paris Agreement to the UN Framework Convention on Climate Change (UNFCCC).
- Governments should modify laws and regulations to have the private sector be transparent about the ingredients used in plastics, which will aid in determining full-lifecycle emissions and impacts on planetary processes.
- Recommendations for the Private Sector
- Businesses operating in any part of the plastics lifecycle should monitor and disclose their contributions to greenhouse gas emissions and the release of micro- and nanoplastics, incorporating these into their sustainability reports, targets, and reduction initiatives.
- Companies can contribute to providing information essential to calculating plastics’ impacts on climate by improving transparency about the polymer makeup of plastics and about the ingredients added to plastics.
