Fwd: Retire the concept of residual emissions
Greg Rau
Retire the concept of residual emissions
Either you accept carbon removal as a climate solution, or you reject it to avoid lock-in. Either way, residual emissions is not a thing.
READ IN APP The concept of residual emissions have played out its role.
Residuals most often refers to remaining emissions to counterbalance with carbon removal at the year net zero is reached. As I explained in my latest article, they only exist because a modelled pathway assumes other mitigation alternatives won't have scaled enough by then.
If CDR counted as mitigation like any other solution, residual emissions would not exist. Then there would only be emissions and carbon removal. When they are of the same magnitude net zero has been reached.
There is also no strong reason to allow CDR at net zero if it isn't allowed to count as mitigation for near-term targets. The usual arguments against CDR substitution, such as lock-in, removal scarcity etc, apply just as much to emissions labelled “residual” at the net zero year.
For the concept of “residual” emissions to make sense you would need some argument for why CDR is allowed at net zero but not before.
Residuals are usually justified as the emissions with no alternative. But CDR is not a must for any CO₂-emission, there are always other alternatives, some are just expensive.
The money spent on carbon removal could have been spent on other mitigation solutions for example scaling e-fuels faster. You cannot derive from first principles where CDR should be allowed if you do not see it as a normal climate solution to be used when it’s the cheapest option (with strict guardrails on quality, permanence and safety).
Either you accept carbon removal as a climate solution, making net zero cheaper and faster, or you reject it to avoid lock-in. Either way, residual emissions is not a thing.
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Michael MacCracken
You might also add permafrost thaw as well. Why these need to be mentioned is not just that they happen, but that the IPCC definition of net-zero is for direct human emissions only---and does not include the imbalance to the natural carbon cycle being created by human-induced climate change. If one wants to end the increase in radiative forcing that leads to warming, humans must not only not be adding additional warming agents to the system, but there must be a balance for the increase in natural system emissions and reductions in sinks that are being caused by climate change. If these emissions are not counted as residual emissions that must be eliminated or have their warming influence counter-balanced by climate intervention, then what are these human-induced emissions to be called?
Mike MacCracken