Solar Radiation Management (SRM), is another form of geoengineering aiming to manage and reduce incoming solar energy reaching the Earth, to counteract GHG forcing. Models indicate that the climate system reacts quickly to artificially reduced insolation, and therefore SRM is often branded as a last resort against 'dangerous' warming.
![]() Fig.1 Illustration of geoengineering approaches (source: IPCC / Royal Society). |
Stratospheric aerosols
- Extensive studies have shown major volcanic eruptions to cool global temperatures over short-timescales (Fig.2). The ejection of sulphate particles in the stratosphere from eruptions causes an increase in diffused solar energy and reduction in total energy reaching the Earth. A natural analogue for the stratospheric release of sulphate aerosols. According to models cooling could start within months of release and cool significantly within decades. Thus, receiving growing traction from scientists and policymakers.
Fig. 2 Mean global average temperatures from 1970-2012 with major volcanic eruptions highlighted (source: Kosaka & Xie, 2013). Albedo enhancement
- Approaches that aim to enhance the reflectiveness of surfaces (land, oceans and clouds) to increase the amount of solar energy reflected into space. For instance, painting cityscape roofs white as suggested by Barack Obama in 2009, to seeding marine clouds to enhance the total of cloud condensation nuclei (CCN) present, thus increasing cloud surface area and brightness.
Space reflectors
- Roger Angel (2006), presented the idea of 100 000km wide 'sunshades' (aka space reflectors) to be placed in outer space. Reflecting and/or blocking incoming solar radiation. Calculating that only ~2% of incoming solar radiation would have to be blocked to offset current warming. In line with calculated energy transfer figures.
Fig.3 An article headline from NY Times (source: Friedman & Thrush, 2017) |
However, a consensus within the scientific community is that SRM is bad and infeasible (I'm a little on the fence about it too). A contemporary argument for this would be the justification for the Trump administration to deny climate change (despite the arguments many USA scientists make Fig.3), disregarding the Paris Agreement and continuing fossil fuel exploitation (ie. pipeline exploration destroying indigenous lands and fracking).
Conclusion
Initially, SRM seems to be a viable climate fix. However, SRM is controversial and prone to issues surrounding governance, equity and ethics.
However, there may be a place for SRM especially if we adopt the business-as-usual approach to climate change. SRM may 'save' us and provide us time to change current social, economic and environmental practices. In this regard, I perceive SRM to be a form of adaptation and not mitigation.
Hi Fay, I really enjoyed reading your blog post. You spoke about the consensus within the scientific community, I just wondered what you thought about other stakeholders and groups getting involved with decisions about SRM. Seeing as it such a risky and dangerous approach that will impact us all, surely the general public need to get involved in this?
ReplyDeleteI absolutely agree with you Parmjeet. The debates on geoengineering is very much constrained to scientists, other academics and international organisations like the IPCC or the Conference of the Parties (COP). This may be because scientists are still uncertain of the implications and whether SRM will be a viable approach to tackling climate change. However, this does not mean scientists have been disregarding the public, check out the SPICE Project (2010), looking at real world stratospheric aerosol injection but aiming to build on public awareness and perception. Scientists are aware of the role of the public in whether geoengineering goes through or not.
DeleteBut, I strongly believe that public awareness of geoengineering does need to be raised and that's why I have decided to post about this. I think unless you have a particular interest in climate change you won't come across geoengineering in your day-to-day life. And as you've said its something that will impact us all so it's important that the public is made aware, especially since geoengineering is increasingly being considered by international organisations like COP21.
So before the general public can get involved they first of all need to be made aware. Which we can help by speaking about it, the media through publicising geoengineering more, for instance the film Geostorm may build awareness and stimulate debates. And perhaps we will soon see and hear David Attenborough touching on this subject in his documentaries like he has with marine plastics in Blue Planet II.
Do keep reading my blog, I aim to address stakeholders and governance in my upcoming posts.