Discounting emissions from temporarily stored carbon creates false claims on contribution to cumulative emissions and temperature alignment

There has been renewed interest in equating temporary carbon storage with permanent CO2 emission reductions, both within corporate GHG inventories and for carbon offset accounting. Proposed methods discount future emissions, such that carbon stored temporarily can be accounted for as (some fraction of) a permanent reduction in emissions. These approaches are problematic as long-term temperature change is primarily caused by cumulative CO2 emissions and delayed emissions accumulate in the atmosphere the same as any other emission of CO2. This paper uses illustrative examples to show how discounting future emissions results in false temperature alignment or net zero claims. We recommend that emissions and removals should be reported without discounting to ensure that GHG accounts accurately reflect contribution to cumulative emissions. There is value in temporarily storing carbon, e.g. it buys time to implement permanent mitigation measures, but it cannot be treated as equivalent to permanent mitigation, and alternative approaches should be used to convey the value of temporary storage.