As discussed in my previous post, geoengineering can be broadly categorised into Carbon Dioxide Removal (CDR) and Solar Radiation Management (SRM). Some make the distinction that CDR is not true geoengineering since it aims to reverse carbon emissions and so is more like pollution mitigation. However the scale at which CDR would need be implemented and the potential side-effects mean that it raises many of the same concerns as its cousin, SRM. SRM is often presented as the more sinister and risky side of geoengineering, but while CDR might be seen as the lesser of two evils it is far from ideal.
Examples of carbon dioxide removal include carbon capture and storage (CCS) and air capture (AC). The distinction is that CCS removes CO2 from fixed point sources such as power plants, i.e. before the CO2 has been released to the atmosphere (and so is a form of pollution mitigation), while AC aims to remove CO2 directly from the atmosphere. In order to have a significant impact on global atmospheric CO2 concentrations AC would need to be implemented on a large scale for a long time, which puts it more into the realm of global climate engineering. The thing is however that this AC technology does not currently exist on a commercial scale (Keith et al. 2006).
In either case, supposing that the CO2 can be successfully captured, it needs to be stored and the most frequent suggestion is in the ocean. Oceans already operate as carbon sinks and by absorbing anthropogenic CO2 emissions the oceans may have diminished and disguised the impact of global warming. The Global Carbon Project estimate that 27% of total emissions from human activities during 2003-2012 were absorbed by the ocean sink. For this reason the ocean is central to many CDR proposals.
One suggestion is to store CO2 so deep in the ocean that the low temperature would change the CO2 from a gas to a liquid, which would be more dense than the water and so would remain in storage. Concerns surrounding this approach are that it would alter the chemical composition of the water, resulting in ocean acidification. Ocean acidification has ramifications for marine species and the development of coral, and in turn would impact human societies that subsist from the ocean. There are also concerns about leakage of carbon from these ocean stores (Nevala & Madin, 2008).
Another proposal to increase the absorption of carbon from the atmosphere into the ocean is to fertilise the ocean with nitrogen in order to promote phytoplankon blooms, which would remove carbon from the atmosphere. Once the phytoplankton die, they sink to the ocean depths, along with the carbon they are storing. The concerns with this approach are the scale on which it would have to be implemented to be effective, and again the potential for altering the chemical composition of the ocean is great. Not to mention the other side-effects, such as the promotion of toxic algae blooms. The cons are troubling and difficult to reconcile, particularly since the effectiveness of this approach is far from guaranteed (Nevala & Madin, 2008).
The Ocean Nourishment Corporation (ONC) however, sees so much potential in ocean fertilization that it “is developing its unique patented ocean nourishment technology”
"ONC’s agenda is to assist in providing scalable solutions to global environmental problems including the excess carbon dioxide waste in the atmosphere and its effects on climate security, ocean acidification and the decline of world fisheries from overfishing, poor management and environmental degradation. These are lofty goals and therefore ONC is no ordinary business, our triple bottom line is environment first, social second and economic third."
So the bottom bottom line is economic?
ONC describe Ocean Acidification as an important issue that “is seriously under investigated”. They acknowledge that “work is needed to clarify the processes, to gain a better understanding of what is happening”. They don’t mention if they are undertaking this work.
I think that understanding the issue of ocean acidification should precede research and development into site selection and nutrient delivery technology, but ONC and I must disagree on this point. The priorities of ONC are particularly interesting since ocean acidification has the potential to diminish ocean biodiversity and productivity, which seems directly at odds with the mission of ONC.
The below link highlights why ocean acidification is so troubling and why it could be worth reconsidering the ocean for carbon storage.
My views were formed by Alan Robock's 20 reasons why geoengineering may be a bad idea. There's also good reasons to doubt the motives of organisations like the ONC, and countries are only likely to get behind geoengineering from a militaristic point of view, at least according to Clive Hamilton's Earthmasters which I've yet to finish.
ReplyDeleteI think you might find my latest post about geoengineering's military associations interesting. I hope it is alarmist to consider that the motivations behind geoengineering could be solely militaristic, but the connections and concerns are still valid.
ReplyDeleteWhile Robock's list of reasons why geoengineering may be a bad idea is both comprehensive and compelling, I don't think that he completely rules out geoengineering, but rather encourages further research with caution and with greater emphasis on mitigation (see Geoengineering: It's not a panacea). That is certainly my own viewpoint; while at present geoengineering is too problematic to be a realistic solution that does not mean that its potential does not merit further investigation, if only to definitively rule it out as an approach.