Developing individual carbon footprint reduction pathways from carbon budgets: Examples with Wallonia and France

Traditional climate strategies focus on long-term emissions targets, neglecting cumulative CO2 emissions and often limiting their scope to territorial emissions. Additionally, individual citizens struggle to connect with community targets. This study addresses these issues by computing a comprehensive carbon footprint pathway that, as a main contribution, can be easily personalized and associated with common carbon footprint calculators. This approach innovatively leverages inverted “S-shaped” patterns based on logistic functions that, unlike common linear patterns, have been documented as relevant for diffusion mechanisms of social or ecological transformations. One challenge lies in efficiently aligning the carbon footprint figures, expressed in CO2eq, with IPCC's +2 °C carbon budgets, expressed in CO2-only. This work first retrieves the current share of CO2-only footprint and then defines two mitigation pathways: one focusing solely on CO2 emissions and one addressing residual GHGs. Except for initial and final emission levels, both targeted pathways are defined by the same logistic function, based on the assumed intrinsic link between CO2 and the other GHGs. As final targets, the CO2-only pathway considers the common net-zero emission goal while the second pathway considers a level of 1 tCO2eq/year per capita of unmitigated non-CO2 emissions, in alignment with IPCC's latest assumptions and anticipated population growth. Besides the new +2 °C compatible suggested pathways, developing this method for France and Wallonia has also revealed that they should reach territorial (nature-based) carbon uptake of at least three times their current levels, necessitating deep land-use changes in their policies (implementing intensive urban vegetation, alternative agriculture techniques, etc).