So yesterday the Royal Society’s report on geoengineering came out, with a launch event and a press conference. It (82pp PDF, press release) is undoubtedly the best overall briefing on geoengineering technologies and their policy/governance implications that you can find right now; John Shepherd and his team did a comprehensive and thoughtful job.
I’m sure that when I get into it in depth I’ll find lots of interesting gems, but here are some highlights
- The overall frame is that none of these options in any way takes the place of emissions control.
- The report makes a clear distinction between carbon dioxide reduction (CDR) techniques — afforestation, burning biomass with carbon capture, biochar, “artificial trees” (possibly the most misleading label any technology is currently labouring under) and so on — and “solar radiation management” (SRM) techniques — sulphate aerosols, cloud-whitening, mirrors in space, etc. CDR interventions will always be very slow to have their effects, while some SRM techniques could be very quick.
- Some of the CDR techniques — those that involve no major interventions in ecosystems — are seen as pretty much unproblematic, if not currently affordable; transnational issues only arise if they start to reduce the carbon dioxide level too far (whatever that might be). CDR that gets into major ecosystem issues — eg ocean fertilization techniques — give greater cause for concern.
- Pretty much all of the SRM techniques are seen as having significant risks, except for painting roofs white, which simply doesn’t do much good.
- In CDR, two technologies stand out: direct-air carbon capture and BECS, biomass energy with carbon sequestration. Both cost a fair bit, but a decent carbon price would help sort that out. BECS has the advantage of producing energy rather than using it; but though direct captureuses quite a lot of energy has the advantage of a footprint that is hundred or thousands of times smaller per tonne of carbon sucked up. Both assume that there are places to put the carbon once it has been purified.
- There’s also more discussion than I’ve seen elsewhere of “enhanced weathering” — reacting carbon dioxide with rocks ground into the soil and things like that. Low on affordability and readiness, and requires a massive new global mining industry, but since it can scale up in a big way worth keeping an eye on…
- In SRM, stratospheric aerosols are the most impressive option, ranking as high as or higher than anything else with comparable potential. The impacts on other things, though, most notably the hydrological cycle, are a worry. In the 1990s the sulphates from Mt Pintaubo not only dimmed the sun — the also dried the world’s rains and reduce the flow of its rivers. Working out how much this effect matters is probably the most important open scientific question in geoengineering (that’s my opinion, not something the report says).
- Cloud-whitening proponents will be disappointed, possibly a little aggrieved, at being seen as consierably less effective than aerosols; proponents argue that they can offset a doubling of CO2. On the other hand the report is kinder than one might expect to space-based systems. “Kinder” here means saying someone should go and think about everything so far proposed in that arena a bit more seriously for a few years and then come back and make a case, rather than simply laughing.
- There needs to be a thorough audit of the many international agreements currently in place for other reasons — the UN framework convention on climate change, the London convention, the Montreal protocol, the law of the sea, the convention to combat desertification, the outer space treaty, the convention on biological diversity, and various others — to see which currently have bearing on any of these techniques, and how they could be used to exert control or to provide incentives.
- The UK should commit to £10m a year for ten years in research; worldwide a suitable figure might be ten times that. As John Shepherd put it, this would be ten times current spending on such things, a tenth of total climate research spending and a hundredth of spending on energy technologies.
All reasonable stuff, it seems to me, and well referenced if not well illustrated. The launch event and press conference, though, did feel a little stifled by worries about being seen as championing the technologies under discussion. The press release was actually headed “Stop emitting CO2 or geoengineering could be our only hope”, framing geoengineering principally as a threat. A little more of a sense that some or more of these technologies might be useful adjuncts to emissions reduction rather than a dread alternative could have been helpful — a little less of a sense that they all must be bad. Interestingly, one of the people discussing the issues at the launch event did go further than others in this, pointing out that if you want to get carbon dioxide levels low enough to do something about ocean acidification you are undoubtedly talking about CDR, not as a “plan B”, but as part of the basic strategy. That was John Beddington, the UK government’s chief science adviser.
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