Overshoot Commission’s veneer of neutrality is solar radiation modification PR by stealth

Calls for a moratorium on solar radiation modification (SRM) today by the Overshoot Commission seem sensible – such sun-blocking technologies are highly risky. Yet in the same breath, the Commission appears to encourage moratorium-busting SRM testing, begging the question – is their new report a trojan horse?

The science-lite report is heavy on political recommendations and weak on what’s most important – reducing the risk that we’ll overshoot the 1.5°C limit in the first place. To do this, the IPCC is clear that the world needs to peak emissions by 2025 before slashing them in half by 2030 to meet the Paris goal. Yet the Commission is silent on this.

The report does state that phasing out fossil fuels must be a priority. Yet, its recommendations lack any specificity, concrete dates or targets from the IPCC and the International Energy Agency (IEA). They mention fossil fuel subsidies, but not the need to end all fossil fuel financing (which still exceeds financing for mitigation and adaptation).

Conversely, SRM – a fringe technofix – is strongly weighted in its report. Yet it is put on par with the other main areas of the Commission’s CARE agenda (cutting emissions, adapting to climate, removing carbon from the air, and exploring SRM). This doesn’t match up with the latest science or government-led discussions at international climate negotiations.

Carbon dioxide removal (CDR), which is also too prominently featured equally comes with sustainability concerns, yet we’ll need it to some extent to bring concentrations of greenhouse gases back down. SRM on the other hand does nothing to address emissions. If for any reason we had to stop deployment, the termination shock would cause temperatures to shoot back up within about a year, triggering climate chaos.

Deploying this highly risky technology could directly trigger droughts and floods, impacting food crops and human health.

The SRM moratorium

The Commission is right to propose a moratorium on SRM deployment and large-scale outdoor experiments. But looking at the fine print, the report appears to actually encourage smaller scale experiments as long as they do not carry risk of “significant transboundary harm.” Who defines what constitutes transboundary harm is unclear, while allowing any kind of testing would chip away at the resolve to ban wide-scale deployment.

The report also “only” proposes further research and governance efforts under specific conditions. But, as carefully mapped out as that might be, the idea that research would only take place in this perfect and controlled state seems idealistic. Especially when testing of SRM, even at a smaller scale, has led to controversies.

A dangerous distraction

Putting faith into SRM at the expense of emission reductions would also squander what we don’t have – time. The report itself acknowledges that any SRM deployment would need to be preceded by decades worth of research and testing. We could waste decades of energy and resources on a hypothetical technology which would be better spent on what we can do today, and we know works: phasing out fossil fuels, accelerating renewable energy, and cutting emissions to zero.

There is a substantial moral and political hazard in potentially proposing a “get out of jail free card” for continuing to emit greenhouse gases. Fossil fuel companies, in particular, are keen at this point to pursue any solutions that could prolong the use of their products.

The discussion around SRM could be a dangerous distraction from the urgently needed emission reductions in this critical decade and the much-needed focus on unlocking the finance and resources needed to roll out renewable energy and its supporting technologies at scale. The report appears to recommend diverting attention, scientific focus, and research budget away from climate science and mitigation research towards SRM, while being light in other areas including loss and damage, for instance.

What the science says about SRM

While uncertainties are high around SRM technologies, the most recent cycle of IPCC reports capture what we do know:

• SRM would not return the climate back to its previous state, as the climate would respond differently to SRM than to greenhouse gases (CWGB SRM). In other words, using SRM won’t be a reliable stopgap in an overshoot scenario while we reduce emissions.
• SRM would introduce a wide range of new risks to people and ecosystems, and none of these risks are well understood scientifically (WGII SPM).
• SRM ‘masks’ climate change, rather than address the cause: greenhouse gas emissions (CWGB SRM). Relying on this technology could therefore cause complacency and delay action to cut emissions.
• As SRM doesn’t deal with ocean acidification, which itself poses major risks to marine life (CWGB SRM).
• Effects only last as long as deployment, so for example ongoing aerosol injections would be needed to counter the long lifetime of CO2 (CWGB SRM).
• There are significant uncertainties on costs (WGIII Chapter 3).
• Sudden termination could cause rapid climate change (CWGB SRM).
• SRM would introduce potential novel risks for international collaboration and peace (CWGB SRM).

In addition to the above, we published new research this year which shows that SRM, often touted as temporary, could well lock the world into a commitment of hundreds of years to fend off higher temperatures.

We analysed over 350 climate emissions pathways out to 2500, based on where governments’ current climate targets are taking us. We found that if solar radiation management is deployed to limit warming to 1.5°C without emissions cuts beyond those currently envisioned by governments, it would have to be maintained for at least a hundred years. In fact, most of the scenarios see deployment needing to take place between 150-300 years and deployment needs of more than 400 years cannot be ruled out.

In short, it would be a multigenerational commitment, putting the sword of Damocles over the heads of generations to come.