“In operationalising the Absolute Global Warming Potential concept, the Kyoto Protocol sets 100 years as the reference time frame over which cumulative radiative forcing is to be measured. Over this 100-year period, the decay curve integral is equivalent to the forcing effect of approximately 55 tonne-years of CO2. Hence, we can infer that removing 1tCO2 from the atmosphere and storing it for 55 years counteracts the radiative forcing effect, integrated over a 100-year time horizon, of a 1 t CO2 pulse emission. Under the terms of the Kyoto Protocol, the AGWP100 of CO2 represents the radiative effect of a pulse emission which any sequestration-based activity is designed to counteract (or indeed, any emission reduction activity is designed to avoid or delay). In effect therefore, as understood by the Protocol, carbon sequestered at t=0 and stored until t=55 is directly equivalent to an avoided emission at t=0 and could be credited accordingly. Any new emission from the subsequent release of the stored carbon at t=55 would not be deemed to have caused any additional radiative forcing effects to those which characterized the start point of the project, measured over the 100-year reference period from the point of emission/sequestration. This timeframe of equivalence between sequestered and emitted CO2 is here called the ‘Equivalence Time’ (Te). The re-emission of sequestered carbon after its storage for t=Te does not affect this equivalence.”[1]
[1] Pedro Moura Costa and Charlie Wilson, An equivalence factor between CO2 avoided emissions and sequestration – description and applications in forestry, Mitigation and Adaptation Strategies for Global Change, Volume 5, Number 1, 51-60
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