Current methods for accounting for natural carbon storage, such as forests, in climate change mitigation efforts do not adequately address the risk of carbon loss due to disturbances, whether natural or human-caused.
Traditional carbon offset and removal credit systems focus solely on the amount of carbon stored and assume it will remain stored indefinitely. However, new research proposes a different approach using the “tonne-year” metric, which factors in both the amount of carbon stored and the duration of its storage.
The tonne-year metric measures the carbon storage’s equivalence in terms of time, recognizing that temporary and permanent storage have different climate impacts and should not be interchangeable. Temporary storage, when credited as equivalent to permanent emissions, does not result in climate neutrality. Instead, it can lead to more long-term warming when the stored carbon is eventually released into the atmosphere.
The new approach suggests measuring and tracking temporary carbon storage independently, considering it as a contribution to climate mitigation rather than merely an offset or removal credit for fossil fuel emissions. The tonne-year metric can accurately measure the climate benefit of temporary storage over time, reflecting its true value in climate mitigation efforts.
Temporary carbon storage can be measured by the rate of increase of tonne-years, allowing for the assessment of climate benefits over time. If carbon is lost due to disturbances like deforestation or wildfires, the climate benefit is negated unless equivalent carbon is preserved elsewhere. This method helps quantify the climate benefit of temporary storage and can be used to monitor and track the actual climate impact of natural carbon storage.
By reimagining tonne-year accounting in this way, it becomes a valuable tool for measuring and enhancing the effectiveness of nature-based carbon storage as a climate mitigation strategy, rather than just an alternative to reducing fossil fuel emissions.