The Engineer has posted a lengthy ask-the-experts article on “geoengineering” that addresses both CDR and solar radiation management (“SRM” — techniques that block solar radiation to reduce surface temperatures, but do not directly target the root cause of climate change, i.e. increased atmospheric CO2 concentrations). The article makes many valid points about CDR, but these good points are lost among a number of misleading comparisons of CDR and SRM approaches.
For example, take a claim that one of the article’s experts, Oxford’s Richard Darton, makes about the risks of large-scale CDR:
“[CDR] would be technically easy to turn down or off if needed, but once the industry was up and running there would be a huge investment of capital at risk if it were prevented from operating.”
There are many real risks around large-scale CDR, including land use questions (ensuring biomass feedstocks are grown sustainable, that such feedstocks don’t displace food crops, etc.) that Darton notes near the end of the article… but the inability for us to “turn off” the CDR “industry” is not one of them. If we ever got into a position where we had too many negative emissions and needed higher atmospheric CO2 concentrations, we could just a) stop paying people to sequester CO2 (a likely condition required for large-scale CDR deployments) and/or b) pay people to emit CO2 into the atmosphere. But more importantly, the probability that we face the problem of too many emissions at any point in the next century is so low that it is ridiculous to even state it as a potential concern.
When Darton goes on to state his first “con” to SRM approaches is that the “commitment to SRM would involve complex logistics, let alone political agreement, and this would take several years to put in place,” it makes it seem like this concern about SRM is as important as the concern around “turning off” CDR. While SRM politics/logistics are complex, the biggest concern about SRM by far is that the science of most prominent SRM approaches remains highly uncertain, and that the unintended consequences of SRM could be considerably worse than its benefits to fight climate change. The questions surrounding SRM are of a completely different nature than those around CDR, and this article does little to explain that crucial distinction.
Later on in the article, Darton rightly points out that:
“The challenge for CDR schemes is to reduce their cost and improve their effectiveness, so that the large scale of deployment becomes less burdensome. It is hard to imagine a scenario in which CDR is applied without at the same time instituting a far more severe control of CO2 emissions, so we ought also to see carbon capture and storage, energy efficiency and renewables as part of the CDR deployment mix.”
This discussion on how CDR can complement GHG emission mitigation strategies is exactly the conversation we need to have around CDR today — yet it really has nothing to do with the common “geoengineering” discussions that involve SRM governance, ethics, efficacy, and unintended consequences.
So let’s separate the conversation on CDR from the conversation on SRM (my post on the need for this separation, here), as articles like this one from the Engineer go to show how good points on CDR can get muddled when CDR and SRM are presented as two branches of the same “geoengineering” tree.