Friday, November 04, 2011

100 Years a Fiction (Part 3)

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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