Purpose <p>The future reduction of greenhouse gas emissions towards climate neutrality requires efficient methods and models to assess transition pathways with effective technology combinations of every economic sector over time. In this paper, we present a novel computational approach which allows modifying time-dependent scenario parameters using the dynamic prospective life cycle assessment (LCA) tool <i>Prosperdyn</i>.</p> Methods <p>Previous prospective LCA models modify a time series of foreground and background inventories for each time step, which is a challenge concerning the required storage capacity and computation time. The presented tool addresses this challenge by modifying foreground and background data independently in separate databases and linking them in a computationally time-efficient way. Dynamics of foreground data are described by absolute as well as quasi-simultaneous time-dependent functions. Additionally, the novel approach considers emissions related to the construction of long-living infrastructure in the actual year of their occurrence, instead of dispersing them among the systems lifetime. Background data is modified using <i>premise</i>, delivering data prospectively modified using selected SSP-RCP paths of integrated assessment models. Scenarios for the production and operation of a future bus fleet serve as a fictitious use case.</p> Results <p>The use case illustrates the significantly reduced computational effort of <i>Prosperdyn</i> in comparison to previous computation methods. The separate consideration of bus operation, bus production, and infrastructure construction allows considering temporal sequences of all main contributors comprehensively. This justifies to apply, in addition to the year-specific global warming potential, the radiative forcing as an absolute climate metric, which provides detailed insights on the environmental impacts without aggregation.</p> Conclusion <p><i>Prosperdyn</i> overcomes recent computational restrictions by decoupling the large and inert background databases from the foreground. Foreground scenarios of effective technology combinations can be iteratively rearranged and recalculated without computationally time-consuming changes in the background. This enables calculations of many scenarios in high temporal resolutions in a short time. Finally, applying relative as well as absolute climate metrics, the new method describes a comprehensive approach for dynamic life cycle assessment of climate neutrality pathways.</p>