Image: Markus Spiske (Unsplash)

Scientists across the globe explore the feasibility of innovative techniques to limit global warming to 1.5°C. SAI (Stratospheric Aerosol Injection) proposes spraying particles into the atmosphere to reflect incoming sunlight and decrease Earth surface temperatures. SAI aims to keep air temperatures below 1.5°C degrees but it does not necessarily reduce ocean warming to a safe target. It follows then that it also doesn’t reduce sea level rise to safe levels, nor does it solve the problem of ocean acidification.The controversial proposal would require global cooperation. This article explores the political governance challenges that could arise if SAI were to be deployed, and how we could solve these challenges. This proposition could be opportune for scientists and politicians to work together, to concurrently limit warming to 1.5°C and foster global cooperation.

As the climate changes and the Earth warms the pressing and potentially irreversible threat it poses to life on our planet increases at an alarming pace. The goal is simple: limit warming to 1.5°C above pre-industrial levels. The Paris Agreement brings this goal into focus by setting a net-zero carbon emissions target by 2050 in order to limit warming to 1.5°C. Sadly, the current efforts outlined by many signatories is unlikely to break enough ground to reach the goal. In response to weak commitments from states, scientists across the globe have been exploring alternative solutions to slow down the rate of warming. 

Enter “Solar Geoengineering” – one of the most frequently discussed approaches to mitigating climate change. The aim is to reflect incoming solar radiation back into space in order to cool the Earth’s surface. One of the ways in which this could be done is through SAI, which aims to mimic the known effects that explosive volcanic eruptions have on the climate. When volcanoes erupt, they release enormous amounts of sulphate aerosols into the second layer of the atmosphere – the stratosphere –swelling into a stratospheric aerosol layer. This newly formed aerosol layer reflects incoming heat from the sun, creating a cooling effect on the Earth’s surface. 

In essence, SAI is underpinned by the idea that mimicking this temporary radiative force on the climate, through continuous injections of sulphur particles by aeroplanes, will reflect enough sun away from the earth to slow down the warming.

Ultimately, SAI would play a role in avoiding climate change that exceeds the limits to easily adapt. A benefit is that, it could buy governments more time to implement effective climate change mitigation and adaptation measures, by slowing warming until these measures are in place. Pursuing SAI is both time and cost efficient relative to other solar geoengineering options, and because of this it is important that policymakers set out to anticipate its impact on political institutions and ultimately on society. It has been estimated that the average direct costs of SAI deployment in a program through to the end of the 21st century would be $18 million per 1°C of warming avoided. This is inexpensive when compared to the estimated cost of carbon dioxide removal, an alternate form of climate geoengineering, which costs over $800 billion/year to remove 650 Gt of carbon dioxide (CO2) from the atmosphere, which is the amount quantified to reduce warming from 2°C to 1.5°C.

The planning stages of SAI necessitates good governance practices because the efficiency, effectiveness and climate outcomes of the programme would be strongly influenced by political choices. There are three primary considerations for the governance of SAI: 

  1. The potential for military use of SAI
  2. Unilateral deployment of SAI
  3. The politicisation of weather and unilateral withdrawal

Each of these brings with it anticipated challenges that require governments to make a strong and legitimate commitment to meeting the goals of the Paris Accord. 

First, the interconnected nature of the global climate system means that deploying SAI in one country or area can affect the climate elsewhere in the world. These effects can be planned for but this outcome has the potential to be weaponised by military actors to affect interstate conflict. Research funders and state institutions – specifically those upholding the rule of law – must be responsible for placing firm restrictions that prevent the weaponisation of SAI. 

The second consideration surrounds the fact that SAI could be unilaterally deployed. Since SAI is a relatively cost efficient option, the actors can vary from a single small state to an alliance of nations or even a private citizen that has accumulated a mass of wealth. Consequently, various interests may underpin the deployment of SAI. To this end, regional cooperation is necessary so that all stakeholders are considered through continuous agreements over long time periods. If done right, greater regional cooperation to ensure the success of SAI can also reduce the potential for regionalised conflict by aligning interests. 

It follows on then, that the third, and greatest, governance challenge is rooted in the potential for SAI to politicise weather and offer the opportunity of unilateral withdrawal. The effectiveness of SAI is in part dependent on lengthy periods of deployment, potentially as long as a century. To facilitate this, strong and lasting global agreements are essential. If one country within the agreement halts deployment of the programme, the unpredictable side of the weather might take over and render harmful outcomes for other areas or regions, despite the overall success of slowed global warming.  

This unpredictability plays out as a consequence of climate change regardless of interventions like SAI. Most recently, the winter storm in Texas, in February 2021, was a clear example of not only how slow governance has been to ready itself for increasing weather extremes, but also of how volatile the changing climate can be. When weather extremes devastate society, political parties and civil society can be co-opted to blame programmes like SAI. This might create distrust for climate science and even science as a broader field, ultimately turning populations away from supporting interventions that will have the long-term effect of cooling the Earth. Fostering societal trust in science and research can concurrently increase general awareness and understanding of climate risk, and prevent SAI from being a victim of domestic party politics. 

Although the risks of SAI seem high, so too are the potential benefits. With well-funded research and global cooperation, the success of the programme would not only cool the earth but also create an overarching global interdependence that like trade, might reduce the likelihood of conflict. 

The topic remains controversial. SAI would produce both winners and losers in terms of local and regional climate outcomes, but with each passing day the need for radical intervention grows larger. Many scientists find themselves questioning the collective ability of humans and institutions in reducing emissions and limiting global warming. There is a growing sense that adopting solar geoengineering technologies is crucial if we are to maintain life on Earth as we know it. The time has arrived for scientists and political actors to collaborate so that innovative programmes are planned and deployed through mechanisms of good governance. As the solutions to climate change come into focus, the need for good governance and cooperation emerge as common denominators.

Trisha Patel is a Master of Science student majoring in Climate Change and Sustainable Development at the University of Cape Town. Her research focuses on solar geoengineering, and her interests include geography, palaeoenvironments and climate science. 

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