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We have just passed the 400 ppm threshold of carbon dioxide (CO₂) levels in the atmosphere. The climate change problem is urgent, and our response so far inadequate. Most scenarios where we avoid very serious impacts – at least those scenarios that do not involve immediate economic collapse and the ensuing social chaos – rely on new technologies. For example ones that suck CO₂ out of the atmosphere and sequester it underground. The technologies needed, however, have yet to be implemented on any scale: in some cases they still only exist on a theoretical level.

These new technologies also come with their own serious problems: both technical and political. Some technologies would take significant areas of land away from food production. Others risk disrupting other aspects of the climate system, for example monsoon patterns.

Very hard choices may need to be made. How all of us, and policy makers in particular, understand what choices are facing us really matters. This of course involves knowing the facts, but is also about how we define and classify these climate changing technologies in the first place.

Definitions matter

In recent years, the main concept through which we discuss these technologies is ‘geoengineering’ or ‘climate engineering’, defined as a set of technologies that promise to counterbalance global warming.

I and colleagues at King’s College, London, and Eurecat, Barcelona have been exploring public understanding of ‘geoengineering’ through a recently published study of how the concept is presented on Wikipedia.

Wikipedia, like most other presentations of ‘geoengineering’, classifies the technologies into two categories: those that suck CO₂ out of the atmosphere (carbon dioxide removal, CDR) and those that reflect some sunlight back out into space (solar radiation management, SRM). But this classification is based solely on their scientific properties, rather than on any political aspect.

Our study used data from Wikipedia to analyse the discrepancy between this dominating, science-based model of how to define and classify geoengineering technology, and the actual practice of how the technologies are classified when discussed in more depth by knowledgable people in public fora.

Wikipedia is, on one hand, an encyclopaedia, favouring scientific apolitical accounts of things, well suited for the dominating model of how to think about geoengineering. But Wikipedia is also an inter-linked network of articles, which generates a structure where we could analyse what technologies are strongly associated with each other. Analysing this structure helped us identify the alternative distinctions and classifications.

How is ‘geoengineering’ discussed in practice?

In practice, we discovered, people tend to actually mean the sun-reflecting SRM when they say ‘geoengineering’, and often, even more specifically, they mean a controversial technology that would work by injecting sulphate particles into stratospheric clouds, which would have global effects. Such a technology comes with practical problems, as you might imagine, but also serious political problems in terms of who decides when and where to implement them and what regional impacts to accept.

The distinction between CDR and SRM type technologies also obscures other relevant political dimensions. For example, technologies that sequester CO₂ on or under land tend to be less controversial than ones proposing sequestration in open seas. Intervening in open systems are in some ways inherently more risky, and risk is an important consideration.

Another example is the distinction between large scale interventions, such as mirrors or lenses in space, and small scale modular technologies, which build up slowly, like painting roofs white. Again there is a different level of risk involved.

So the strong emphasis on the umbrella term of ‘geoengineering’ and the CDR-SRM distinction are problematic in themselves. They tend to hide controversial and politically sensitive issues. 

Dig a little deeper

When digging deeper into how people write about geoengineering in public fora, distinctions other than the CDR-SRM divide become more important. For instance the distinction between technologies that intervene with open systems, or closed systems discussed above. 

Another distinction that becomes visible when you dig deeper is between those geoengineering technologies that have potential for military use and those that don’t. You will also find that some of the technologies have industrial involvement and others do not.

But will the policy makers dig deep enough?

Based on this study, it’s clear that policy makers need to be aware that the umbrella term of ‘geoengineering’, and the CDR-SRM distinction, may hide as much as they reveal. Policy makers would be well advised to dis-aggregate the umbrella term. They should also use multiple classifications of the technologies, including ones that explicitly address political as well as scientific aspects.

Read Nils’ research article in Big Data & Society here.