ncx-gitbot
commented
1 year ago NCX response: A tonne-year is simply a unit of carbon account like a kilowatt hour is to a kilowatt for electricity, a unit of volume over time. While tonne-year accounting may not be used widely today in the voluntary carbon market, it has been supported as an alternative to traditional carbon accounting in the scientific literature for many years. One cannot adequately know the full benefit of a solution without adding in the time or duration term. Fundamentally, tonne-year accounting allows for the delivery of realized impact, not presumed future impact on timescales incongruent with the variability of natural systems. Furthermore, tonne-year accounting allows the direct comparison of benefits of different carbon offsets approaches over many different time scales and technologies.
Commenter Organization: Carbon Solutions Lead, Pachama Inc.
Commenter: Cindy Chiang
2021 Deferred Harvest Methodology Section: No Section Indicated
Comment: Tonne-year accounting is fundamentally arbitrary. In addition to arbitrary economic assumptions (e.g. time horizon of cost-benefit analysis, discount rate, etc.), any tonne-year method rests on enormous assumptions about the atmospheric lifetime of carbon dioxide. This atmospheric lifetime is an emergent property of the earth system. It changes through time and can only be quantified with large uncertainty. Tonne-year accounting represents this atmospheric lifetime with an impulse response curve, an extreme simplification. Crediting outcomes are highly sensitive to the shape of this impulse response curve.
Proposed Change: No Proposed Change