Spray and Pray – The risky business of geoengineering Africa’s climate

Solar geoengineering, whether through space mirrors or stratospheric particles, is a complex, controversial and contentious field. In a webinar on Tuesday, atmospheric scientists and other experts from across Africa agreed that it is completely rational to explore its role in a portfolio of climate change responses. 

Geoengineering refers to deliberate, large-scale interventions in the Earth’s natural systems with the aim of counteracting climate change. The primary goal of geoengineering is to mitigate the adverse effects of global warming and manage the Earth’s climate system. There are two main categories of geoengineering: Solar Radiation Management (SRM) and Carbon Dioxide Removal (CDR).

The webinar focused on the former, which The Alliance for Just Deliberation on Solar Geoengineering says refers to “deliberate, large-scale interventions in the global climate system to increase the amount of sunlight reflected away from the planet to reduce global temperatures”.

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The Intergovernmental Panel on Climate Change (IPCC) in its Sixth Assessment Report defines SRM as “a range of radiation modification measures not related to greenhouse gas mitigation that seek to limit global warming. Most methods involve reducing the amount of incoming solar radiation reaching the surface, but others also act on the longwave radiation budget by reducing optical thickness and cloud lifetime.”

(Source: The Alliance for Just Deliberation on Solar Geoengineering)

Hassaan Sipra, director of global engagement at The Alliance and a climate researcher, explained that SRM – in line with conclusions by the IPCC – is not meant to stop climate change but only to buy time for the deep reductions in greenhouse gas emissions needed to limit global warming. He also set out the context wherein SRM was an increasingly attractive area of research. 

During the UN climate conference in Paris, the world agreed to accelerate efforts to limit the global average temperature increase over pre-industrial levels to below 1.5°C. At present, we are on a trajectory to exceed even 2°C. This is important because every fraction of a degree drastically increases the risks associated with anthropogenic climate change. 

“And typically, now, within this context,” said Sipra, “what is being talked about is the use of carbon dioxide removal technologies. So we know that we’re not going to get to net zero emissions until about 2100 if we’re looking for 1.5°C. If it’s 2°C, we’re not going to get there until after 2100. So in the meantime, we also need to start scaling up our carbon dioxide removal technologies so that whatever carbon is in the atmosphere, we are immediately able to capture it and bring that back.”

Put differently, carbon removal will still be necessary in the future because even with significant reductions in greenhouse gas emissions, existing atmospheric carbon levels must be reduced to meet net zero targets and stabilise global temperatures, as outlined in the Paris Agreement. This ensures long-term climate goals are achievable by offsetting any remaining emissions.

Read more: Earth could exceed 1.5°C ‘dangerous climate change’ threshold by December 2034 – WHO

Sipra explained that the problem with carbon dioxide removal was the interrelated problems of cost and scale. 

It’s “an expensive technology or a set of technologies that would take a long time to scale up and would require a tremendous amount of resources, and at present, those resources are not yet scalable… they’re not yet available, the technologies are not yet fully tested, and so we need a lot of time before we’re going to get to carbon dioxide removal technologies.

“We need time to cut emissions and we need time to get to carbon dioxide removal technologies. Yet climate impacts are continuing to rise in the meantime. And this is the point where for scientists, policymakers, civil society, the deliberation has begun as to what might be the possibility of buying some additional time; putting in a potential stopgap measure.”

Napkin diagram roughly showing SRM’s role in managing climate risks.(This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.)

SRM is a “stopgap measure”, Sipra explained, in contrast to emissions reductions or carbon dioxide removal because “it does not actually offer a solution to our climate problems, it merely masks it. And so, without addressing the root cause of climate change, you are kind of just giving yourself this, in essence, a drug which may delay – potentially – some of the impacts of climate change”.

But just how is SRM meant to achieve this? 

Prof Babatunde Abiodun, an expert in climate model developments and applications, shared some details on the state of SRM research and the various approaches being explored and experiments undertaken. Three of the projects he noted are highlighted here:

• Stratospheric Aerosol Processes, Budget and Radiative Effects (SABRE): SABRE investigates how tiny particles in the stratosphere may reflect sunlight to cool the Earth. The project is “an extended airborne science measurement programme” and aims to understand the effectiveness and potential impacts of these aerosols so as to strengthen the “scientific foundation to inform policy decisions related to regulating global emissions that impact the stratosphere (eg ozone depleting substances, rocket exhaust) and the potential injection of material into the stratosphere to combat global warming (climate intervention)”.


• Stratospheric Controlled Perturbation Experiment (SCoPex): SCoPex, a Harvard University-led project, explores the feasibility of dispersing reflective particles in the stratosphere to mimic volcanic cooling effects using a high-altitude balloon to release small amounts of aerosols over a small area. However, the project has recently moved away from its focus on science related to solar geoengineering.


• Geoengineering Assessment Across Uncertainties, Scenarios and Strategies (GAUSS): GAUSS evaluates the potential risks and benefits of various geoengineering methods by using complex computer simulations. Early findings suggest that while geoengineering can reduce global temperatures, it may also lead to regional climate changes, emphasising the need for careful, scenario-based planning. They explain that “one challenge today is a degree of arbitrariness in the scenarios used in current SRM simulations”.

SRM and other geoengineering approaches, however, are not without controversy. The main concerns are the potential for unintended environmental side effects, ethical issues regarding the manipulation of natural systems and the risk of unequal impacts on different regions potentially exacerbating global inequalities.

The IPCC says in the Summary for Policymakers of its Sixth Assessment Report that, with high confidence, “solar radiation modification approaches, if they were to be implemented, introduce a widespread range of new risks to people and ecosystems, which are not well understood. Solar radiation modification approaches have the potential to offset warming and ameliorate some climate hazards, but substantial residual climate change or overcompensating change would occur at regional scales and seasonal timescales.

“Large uncertainties and knowledge gaps are associated with the potential of solar radiation modification approaches to reduce climate change risks. Solar radiation modification would not stop atmospheric CO₂ concentrations from increasing or reducing resulting ocean acidification under continued anthropogenic emissions.”

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To this, the gathered scientists and experts said that while they recognised the potential risks, these should be weighed against the risk of the status quo or inaction.

“It makes sense to think about SRM as a very risky proposition, but it’s a risky proposition that has to be compared to an alternative risky proposition, which is worsening climate change. So, climate change increases risks to peoples and ecosystems. With each ton of carbon dioxide we’re adding into the atmosphere, with each incremental bit of warming, those risks rise exponentially.

“So, just like climate change has its risks, SRM has risks. It also has potential benefits, and it has a large amount of uncertainties, and none of them are well understood. So, in order to make a comparison against climate change with SRM, we need to really have an informed decision-making process around SRM so that we can have a better sense of its benefits and its drawbacks,” said Sipra.

“We need to explore SRM in the context of worsening climate change,” he said, adding that geoengineering would “not be a discussion if the climate situation had been resolved after the Rio summit when they formulated the UN Framework Convention on Climate Change.

The fact that the climate is getting worse; the fact that we are not mitigating, is the reason people are beginning to have a conversation about SRM. So, it can only ever be contextualised in comparison to climate change.” DM

https://www.youtube.com/watch?v=REeWvTRUpMk