The way we think about carbon emissions and storage is evolving. While much attention is paid to fossil-derived carbon emitted into the atmosphere, researchers are increasingly focusing on how much is retained in human-made products. A recent study published in Cell Reports Sustainability estimates that each year, approximately 400 million tons of fossil carbon are added to durable products like plastics, buildings, and infrastructure. This “technosphere” —the total sum of all human-made artifacts— could be seen as a growing carbon sink, though it also presents significant challenges for waste management.

The Technosphere: A Growing Reservoir of Carbon
“We have accumulated more carbon in human-made stuff on the planet than there is carbon in the natural world, but we completely overlook it, and those stocks get bigger and bigger,” says Klaus Hubacek, an ecological economist at the University of Groningen and senior author of the study. The research highlights the need to shift focus from carbon flows (emissions) to carbon stocks (stored carbon in products).

Using global data from 2011, the team analyzed the fossil carbon content in products, factoring in both end-use products like plastics and bitumen as well as intermediate feedstocks used in industry. They found that 9% of extracted fossil carbon in 2011 was retained in durable goods within the technosphere. If this carbon had been emitted as CO2, it would have almost equaled the European Union’s emissions for that year.

Carbon in Construction and Materials
The construction of buildings and infrastructure accounted for the highest share of accumulated fossil carbon (34%), followed by rubber and plastics (30%), and bitumen, a material commonly used in roads and roofing (24%). Machinery and equipment accounted for an additional 16%. Between 1995 and 2019, researchers estimate that 8.4 billion tons of fossil carbon were added to the technosphere, equating to about 93% of global CO2 emissions in 2019.

This growing reservoir of fossil carbon represents both an opportunity and a challenge. While these materials act as a form of carbon storage, their disposal often results in environmental hazards. Products end up in landfills, incinerated, or as litter, with only a small fraction recycled. During the studied period, 3.7 billion tons of fossil carbon were disposed of, with 1.1 billion tons recycled, 1.2 billion incinerated, and the rest buried or lost as litter.

The Role of Design and Policy
The study emphasizes the importance of increasing product lifetimes and improving recycling rates to minimize the environmental impact of fossil carbon-based products. Designers, architects, and product developers can contribute by prioritizing circular design principles, using materials that are easier to recycle or biodegradable, and exploring alternatives like biogenic carbon. Policies aimed at reducing landfill waste and promoting recycling infrastructure are also crucial.

Future Directions: Biogenic Carbon in Durables
Looking forward, researchers plan to assess the potential of biogenic carbon—carbon derived from plant materials—for durable goods. By diversifying carbon sequestration strategies, including using wood and other bio-based materials in construction, it may be possible to create products that both store carbon and reduce reliance on fossil-derived materials.

The findings provide valuable insights for material innovators across disciplines, particularly those working in construction, architecture, and product design. With a focus on sustainability and circularity, the technosphere’s growing carbon stocks could become part of the solution to global carbon challenges.

Source: Science Daily
Photo: anna-m. w.