Dynamic carbon accounting alters the interpretation of emissions in forest–wood product systems

Engineered wood products are widely promoted as climate mitigation options in the building sector, yet their assessment remains dominated by static lifecycle metrics that aggregate emissions and removals over fixed time horizons. Such approaches obscure the temporal separation between rapid industrial emissions and delayed biogenic carbon uptake in forest–wood product systems. Whether explicitly resolving time changes the interpretation of mitigation outcomes for bio-based construction materials remains unclear. Here, we develop a dynamic carbon accounting framework that links forest growth, harvesting, manufacturing, and residue fate on a common time axis. Applied to an Australian plantation-to-cross-laminated timber supply chain under alternative residue and energy scenarios, the framework shows that static 100-year global warming potential (GWP₁₀₀) and dynamic characterisation produce different interpretations of carbon payback timing and long-horizon cumulative outcomes from the same underlying inventory. Carbon payback occurs at around 12 years under static characterisation, but at around 13–19 years under dynamic characterisation. The results indicate that forest-side carbon accumulation determines the broad payback conditions, whereas downstream industrial processes, energy assumptions, and residue routing more strongly shape post-payback trajectories. Dynamic carbon accounting therefore complements static assessment by clarifying when climate benefits occur under time-bound decarbonisation goals.