The False Dilemma of Decarbonization and Solar Radiation Management

This post is based on the preprint “Safeguarding the polar regions from dangerous geoengineering” by Martin Seigert from University of Exeter and 41 other authors.

Let me start by saying I sympathize with and support their effort to scrutinize Solar Radiation Management (SRM) proposals. Unfortunately, I am missing a risk-risk analysis, comparing the risks of interventions with the risks of non-intervention.

Arctic wallpaper from https://wallpapercave.com/wp/wp4329543.jpg

While the authors recognize that we are approaching a catastrophe in the Arctic (I added boldface):

Human-caused global warming reached 1.3°C above the preindustrial level in 2023 (Betts et al., 2023; Forster et al., 2024). The Arctic is currently warming three times  faster than the global average (AMAP, 2022; Rantanen et al., 2022), resulting in unprecedented loss of sea ice extent and volume (Meier et al., 2023; Notz & Stroeve, 2018), changes in snow duration and extent (Mudryk et al., 2020), widespread permafrost thaw (Biskaborn et al., 2019), glacier retreat (Hugonnet et al. 2021), accelerating Greenland ice loss (Otosaka et al., 2022), increasing wildfires (Descals et al. 2022), changing vegetation distributions (Myers-Smith et al. 2020), and other profound ecosystem changes. These changes are already impacting the daily lives of indigenous and local communities (AMAP, 2022) that rely on local-to-regional resources.

They (still) seem to believe the 2015 Paris goal of 1.5 C max 2.0 C global warming can be reached with “rapid and deep decarbonization to “net zero” carbon dioxide emissions” by 2050.

While this is a laudable aspiration, that I fully support, we cannot and should not ignore that fossil fuel emissions are still increasing globally. In addition to the complexity of the energy transition, it seems that the climate is warming more quickly than expected by the IPCC [see for example: Global warming in the pipeline].

Yes, we need to press for decarbonization ASAP, without a doubt, but it seems irresponsible to me to ignore the fact that current strategies have failed to reduce global emissions, and that the 1.5 C Paris goal is essentially history. Given these realities, we need to prepare for inevitable, dangerous global warming.

Personally, I advocate for dual action: i) yes indeed, an agressive emissions phase-out strategy, personally I advocate for a carbon takeback obligation for fossil fuel producers and geological net zero by 2050 in countries with the highest historic per capita carbon footprint ii) research into planetary cooling options (with Tycho Consultancy I work on marine cloud brightening).

The Seigert et al. consider six polar geoengineering proposals:

1. Stratospheric aerosol injection

2. Sea curtains

3. Glass beads

4. Arctic ice thickening

5. Slowing ice sheet flow

6. Ocean fertilization

Frankly, I essentially agree with the objections presented by the authors. But contrary to the authors, I do not support a ban on research. Partly because I believe in intellectual freedom, and partly because better proposals may emerge from such investigations.

Ultimately, the desirability of geoengineering depends on risk assessment. While the authors of the manuscript do a good job discussing the risks associated with polar geoengeering proposals, I am missing an assessment of the risks that could be mitigated, if the proposals were able to achieve their stated goals.

SRM debunked?

Part 2 of the manuscript is called “Debunking geoengineering arguments”

Argument 1: Mitigation is not happening fast enough

The authors admit that the world is not on track to meet the 2030 Paris Agreement goals, but they maintain that net zero by 2050 could still be reached. This to me appears wishful thinking. And a rather meaningless assertion, without discussing the pathway towards net zero, and assessing the likelihood of actually achieving this goal by 2050.

Essentially, the authors agree that mitigation is not happening fast enough, but, against all odds, they suggest we should trust it will be all fine in the end. Although, I hope they are right, this sounds a bit like a fairy tale to me.

Argument 2: It is our moral duty to look at “all the options”

Here the authors present geoengeering research as a “moral hazard”, without acknowledging that refraining from geoengineering research also constitutes a “moral hazard”. A moral hazard is understood to be an action that increases our exposure to risk. In this context I would like to point out that banning geoengineering research also counts as an action, and that the risks associated with this action may be huge.

The second objection against geoengineering research is “mitigation deterrence”. In my opinion rightfully, the authors argue:

Discussions of geoengineering can lull actors, whether individual or collective, into complacency […] there is the risk that attention to geoengineering might reduce engagement with decarbonization […]

And I also share their concern about “predatory delay”:

Predatory delay differs from the form of delay discussed above, which is a largely unintended consequence of the complacency generated by a particular action. First introduced by Steffen (2016), the term predatory delay refers to deliberate efforts by powerful institutions, such as fossil fuel firms and petrostates, to slow the implementation of actions that address root causes of problems in order to preserve their own financial and political power.

And this makes sense as well:

There is also a growing literature on how geoengineering funding (including from super-rich individuals and foundations), while being based on a perception of “moral duty”, may lead to the installation of undemocratic values and power relations […]

Considering the risks of mitigation deterrence and predatory delay, and the fact that SRM by nature has wide and potentially far reaching impacts, both desirable and undesirable, I think we should be encouraging public funding, rather than dismissing it. The figure below shows that SRM research is dominated by private interests. In this light, I think it is wise the UK Advanced Research and Invention Agency (ARIA) is now supporting SRM research.

From Germany's main environmental protection agency: Umwelt Bundesambt (UBA) [source PDF]

Argument 3: Geoengineering will “buy us time” to adapt and find other solutions

In short the argument presented here is that developing geoengineering will take time and that decarbonization can and should be achieved more quickly. Again, this argument pivots on the net zero by 2050 scenario discussed in Argument 1.

Argument 4: Geoengineering will prevent tipping points being crossed

While several studies frame SRM as a means to delay the crossing of potential tipping points (Xie et al., 2022; Moore et al., 2019; Sutter et al., 2023; Chen et al., 2023), they indicate that it is less effective than GHG mitigation strategies.

Given the substantial uncertainties and challenges associated with geoengineering, it should  not be relied upon as a dependable solution to prevent Earth system tipping points being passed.

Agreed, and agreed. But should geoengineering not be researched for this reason? One could say exactly the same about relying on rapid decarbonization:

“Given the substantial uncertainties and challenges associated with geoengineering decarbonization, it should not be relied upon as a dependable solution to prevent Earth system tipping points being passed.”

Weren’t we all told not to put all the eggs in one basket? Why bet on one horse, I wonder.

Net zero by 2050. Yes. But how? And what if…

They continue The focus, therefore, should remain on aggressive emission reduction strategies, robust adaptation measures, and developing a deeper understanding of Earth system tipping  points to minimize associated risks. Yeah, sure, agreed again. What should such “aggressive emission reduction strategies” look like? Saying this, without offering viable examples of such strategies is very disconcerting to me.

Surely, the authors are not oblivious to the fact that, so far, emission reduction strategies have been largely ineffective, despite the establishment of the United Nations Framework Convention on Climate Change in 1992, and 29 Conferences of the Parties (COPs) since 1995. In this regard the authors seem a bit out of touch with reality.

Sure enough, the authors again mention decarbonization in Part 4: “Protecting the polar regions without geoengineering”. But again they do not get any further than stating the goal: “Rapid decarbonization to “net zero” emissions by mid-century”, without offering a pathway that might get us there.

My 2 cents

I think the public debate should be more frank about the likely very serious impacts of global warming that are upon us, such as, but not limited to, mass suffering and death, and associated mass migration, ecosystems collapse, and the crossing of irreversible climate tipping points.

Given these extreme risks, I think it should be clear that the root cause of climate change should be tackled as a national and global security issue, allocating adequate policy and financial resources to reach geological net zero. (Why geological net zero rather than just net zero is discussed in this post: What to do with the Remaining Fossil Fuel Reserves?)

I think it is also fair to inform the public that dangerous global warming is probably inevitable. In fact, impacts are already felt, and they will become more severe under any mitigation scenario. Accepting this, we are confronted with a moral dilemma regarding cooling options.

Suppose we follow the recommendations by Seigert et al. and a refrain from SRM research. Then, what will advocates of a ban on research tell their children, say 25 years from now, I wonder. By then the world may be suffering severe consequences from global warming and people may wonder “Why on Earth did they refuse to consider cooling options back in 2025?” Under such circumstances, I doubt the arguments offered in the manuscript will sound convincing.

Decarbonization versus climate cooling is a fase dilemma in my opinion. I would rather argue that decarbonization is a necessary condition for SRM. It should be made clear that SRM should never be deployed without a credible net zero strategy, because of termination shock risks and ocean acidification. Considering SRM as an alternative to aggressive decarbonization is completely irresponsible. In my opinion, this point should be made every time SRM is mentioned.

Decarbonization versus climate cooling is a fase dilemma in my opinion. I would rather argue that decarbonization is a necessary condition for SRM.

In Kim Stanley Robinson’s science fiction novel “Ministry of the Future” India is struck by a horrendous heatwave and unilaterally decides to try and protect the people from deadly heat stress with stratospheric aerosol injection. A move that in reality indeed could lower temperatures in India, but not without changing the climate across the globe for years to come. I think that many agree that this type of geoengineering should be avoided, while they will also appreciate a country’s desperation under extreme heat stress.

To be able to have a meaningful discussion about SRM we will have to do research and assess feasibility, benefits and risks. If we do not do our homework now, my fear is that we might end up with less than optimal climate interventions, such as the scenario in “Ministry of the Future”. Therefore, I believe, we need to assess a range of cooling methods, with the emphasis on approaches that are inherently less risky, and more controlled, such as marine cloud brightening.