In a study published in Cell Reports Sustainability, researchers estimate that humans add around 400 million tons of fossil carbon to long-lasting products each year. This carbon is stored in products such as plastics, buildings, and infrastructure, which could be considered a carbon sink. However, proper waste management is essential to prevent these products from becoming environmental hazards. The researchers emphasize the need to focus on stocks of fossil carbon in these human-made products, rather than just the emissions that are commonly tracked.
The researchers utilized publicly available data on material inputs and outputs from different economic sectors globally to estimate the stocks of fossil carbon in the “technosphere,” the sum of all human-made artifacts. They found that in 2011, 9% of extracted fossil carbon was accumulated in long-lasting products within the technosphere, equivalent to almost the entire emissions of the European Union that year. Construction of buildings and infrastructure accounted for the highest accumulation of fossil carbon, followed by rubber and plastic products, bitumen, and machinery and equipment.
By extrapolating their 2011 findings, the researchers estimated that 8.4 billion tons of fossil carbon were added to the technosphere between 1995 and 2019, representing around 93% of global CO2 emissions in 2019. The amount of carbon entering the technosphere increased yearly during this time period. Many of these fossil carbon-based products end up in landfills or as litter, taking decades to centuries to degrade. Recycling, increasing product lifetime, and enacting policies to minimize landfill waste discharge are suggested as ways to reduce fossil carbon entering waste streams.
The researchers highlight the dual nature of fossil carbon stored in human-made products, noting that while it can be considered a form of carbon sequestration if stored in landfills, it also poses environmental hazards, especially when burned. They stress the importance of increasing recycling rates and the lifetime of products to reduce fossil carbon waste. The team plans to further analyze biogenic carbon, derived from plant materials, to assess the potential for diversifying carbon sequestration strategies, such as using wood materials in construction, to reduce the environmental impact of fossil carbon accumulation in human-made products.
Overall, the study sheds light on the significant amount of fossil carbon stored in human-made products and the implications of improper waste management. By focusing on stocks rather than just emissions, the researchers provide valuable insights into the role of these products as potential carbon sinks. Moving forward, the team plans to explore the long-term potential of biogenic carbon sequestration in durables, offering insights into alternative strategies for reducing the environmental impact of fossil carbon accumulation in human-made products.
