Radiative forcing-based accounting (RFA): a dynamic framework to replace static GWPs in carbon markets

Abstract Global carbon markets rely on the 100 year global warming potential (GWP 100 ) to convert non-CO 2 greenhouse gases into CO 2 -equivalent units (CO 2 e). While GWP 100 provides simplicity and international consistency, its fixed time horizon involves trade-offs when applied to short-lived climate pollutants, as it does not differentiate between the timing of mitigation within project lifetimes. This can be consequential for short-lived climate pollutants whose radiative forcing is concentrated in the near term. This paper introduces radiative forcing–based accounting (RFA), a time-resolved framework that offers an alternative approach to equivalence metrics in carbon offset crediting. Derived from radiative efficiencies and atmospheric decay functions, RFA replaces fixed multipliers with dynamic integration horizons that reflect project duration and implementation timing. The framework allows policymakers to define a policy horizon ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> </mml:math> ) while adjusting the effective integration period based on project characteristics, expressed as <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>T</mml:mi> <mml:mstyle scriptlevel="0"/> <mml:mo>=</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mi>H</mml:mi> <mml:mstyle scriptlevel="0"/> <mml:mo>−</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mi>L</mml:mi> <mml:mstyle scriptlevel="0"/> <mml:mo>+</mml:mo> <mml:mstyle scriptlevel="0"/> <mml:mi>t</mml:mi> </mml:mrow> </mml:math> , where <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> </mml:math> represents project duration and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>t</mml:mi> </mml:mrow> </mml:math> the implementation year. We apply RFA to four methane mitigation projects under the UNFCCC Clean Development Mechanism, spanning landfill gas recovery, coal mine methane capture, and wastewater treatment. Across all projects, RFA yields higher credit allocations than legacy GWP 100 (Second Assessment Report), with differences ranging from 36% to 40% depending on project duration and abatement timing. These differences arise from the distinct temporal aggregation inherent in the two approaches. Because RFA requires only a computational adjustment and no modification to existing monitoring, reporting, and verification systems, it can be implemented within current carbon market infrastructure while giving incentive for short lived pollutant mitigation. The framework contributes to ongoing discussions on climate metrics by offering policymakers greater temporal resolution in crediting contexts where the timing of climate benefits is a relevant policy consideration.