The store of fossil carbon in man-made buildings and products is rising, as our dependence on fossil ... [+] fuels continues to increase.Getty ImagesNew research has revealed that the amount of fossil-derived material used in construction, manufacturing and industry is now outpacing growth in the burning of oil, gas and coal, amounting to what scientists say is a "ticking time bomb" of emissions.Researchers in the Netherlands found that over a 24-year period, 8.4 billion tons of fossil carbon were added to buildings, products, roads and other infrastructure, while 3.7 billion tons of fossil carbon re-entered the environment as landfill, via burning, and as other sources of waste.The paper, published in the journal Cell Reports Sustainability, reveals that between 1995 and 2019, the share of fossil carbon going into products increased from about 5% to more than 7% of total fossil fuel usage. That's in spite of an ongoing global increase in the burning of fossil fuels for energy, with the Global Carbon Budget last month finding that carbon dioxide emissions from fossil fuels and cement will rise to a record 37 billion metric tons in 2024."The accumulation of fossil carbon in stocks is growing faster than that of fossil carbon-related emissions," says report senior author Klaus Hubacek, an ecological economist at the University of Groningen. "This means that, while we are in some countries on the path of decoupling fossil fuels from economic growth, the global economy is increasingly dependent on hydrocarbons for its material needs."In their paper, Hubacek and colleagues show that products made from fossil fuels, from the plastics used in appliances to bitumen used for road surfaces, are making up increasing proportion of our built environment, which researchers call the "technosphere." Thats a problem because that store of fossil carbon is temporary. In other words, its "a ticking time bomb, due to a potentially huge amount of additional emissions to the atmosphere," Hubacek tells me.MORE FOR YOUThe report is significant because, while a great deal of attention is given to emissions from the burning of fossil fuels, relatively little work has focused on the amount of fossil carbon in the things we make. "It was with amazement that, while doing this research, we realized that never before has been assessed the carbon balance of the technosphere at any level, not national nor global," Hubecek says.Previous research has shown that human-made products exceeded the mass of the living world in around 2020. This new study indicates that humans are continuing to outpace the natural world in the quantity of material we are producing.One explanation for the growing share of fossil carbon entering our buildings and products, suggests report author Franco Ruzzenenti, could be the rapid development of more complex products that require larger quantities of fossil fuel-based materials, such as plastics. The researchers found that synthetic rubber and plastic products, which are made predominantly from oil and gas, now account for 30% of fossil carbon in products and infrastructure. The more complex artifacts become, the higher the ratio between stocks and flows, Ruzzenenti explains.Another important factor is the fossil fuel industry's growth strategy: research earlier this year from Lawrence Berkeley National Laboratory shows that oil and chemical giants are on course to double or even triple the production of plastics by mid-century. As humanity begins to move away from burning fossil fuels for energy, oil and gas giants are looking to pivot to the production of non-fuel products, rather than conventional fuels, to remain profitable."Combined with the rubber and plastics embedded in various types of machinery, rubber and plastics represent more than two-thirds of fossil carbon in stocks of long-term products, both in households and in industry," says Hubacek. It is therefore "not surprising," he adds, "that the oil industry is leveraging on feedstock-related applications amid [the] energy transition. Indeed, our results suggest that the global economic path is heading toward a higher dependency on fossil fuels for feedstock."To tackle this, the researchers say, will require a multi-pronged approach, based on waste hierarchy of "reduce, reuse, recycle." This would require wealthy countries to "reduce consumption, effective management of landfills to mitigate carbon leakage to the environment, extension of product lifetime, and increase recycling to curb reliance on virgin fossil carbon stocks," the authors say.Most important, the authors stress, is the need for material accounting systems at the national and international levels. "A more effective carbon emissions inventory should account for the two-pronged purpose of fossil fuels," Hubacek tells me. "At present, this is rarely done."Earlier this year, researchers at the University of Oxford proposed a four-step roadmap for reducing the production and use of plastics, noting that individual action alone would not be sufficient to tackle the plastics problem. Early in December, negotiations in South Korea for an international treaty to curb plastic waste pollution failed to reach an agreement, with campaigners saying the process had been "captured" by industry.