Dear polar scientists, engage with climate reality
Image: Pietari Purovaara
Assessments of climate interventions, or geoengineering, are much needed, and we welcome critical contributions. A recent article¹ by Siegert et al. brings forth many real flaws and concerns of some interventions, and in our perspective, we have a shared mission to preserve polar regions, and mitigate global warming. However, contextualization and framing matter, and they come with great responsibility when experts are talking about the climate crisis. In our view this study unfortunately distorts intervention discourse with cheap rhetoric and argumentative flaws. As non-scientists but younger civil society actors, we wish to highlight five perspectives of our own.
1. There is no alternative to emission reduction measures. Arguing that geoengineering would generally be proposed as such is misleading.
Having worked over three years close to the field of geoengineering research, Operaatio Arktis has never encountered a scientist who would suggest we should not accelerate mitigation efforts. However, Siegert et al. reject further research efforts in geoengineering while arguing that we should rather focus on mitigation than turn to geoengineering. Basing argumentation on an “either-or” framing between emission mitigation and geoengineering research creates a biased view on our options. In the field of geoengineering research, it is well known and communicated that any consideration of geoengineering activities in fact highlights the need for decarbonisation further.
2. Lowest-emission scenarios should not be treated as default trajectories.
Siegert et al. argue that mitigation is accelerating and suggest that by 2100 we are headed for roughly 3°C under current policies, 2.5°C if all pledges are met, and 2°C if long-term targets are fulfilled. In other words, we are heading with full speed towards an overshoot, which means more extreme weather events and triggering several irreversible Earth System Tipping Points especially in the polar regions.
Authors then conclude: “While this shortfall in climate action is concerning, it does not justify turning to geoengineering as a solution.”
While geoengineering should not be seen as a silver bullet solution to the climate crisis, we partly disagree. That shortfall is precisely why research on geoengineering should remain on the table. At this stage, relying purely on emission mitigation and the limited scaling of CDR to keep us within safe limits looks increasingly risky.
Siegert et al. also cite figures suggesting a 1-in-5 chance of limiting warming to 1.5 °C – derived from the most optimistic scenario (Scenario E) in Rogelj et al. (2023)2. But Rogelj et al. (2023) explicitly warn against treating these scenarios as likely:
“Although these figures may suggest that the Paris Agreement climate goals are well within reach, the fact that about 90% of assessed net-zero targets score a lower or much lower confidence of achievement confirms that, in reality, concrete and credible efforts to achieve these low-temperature projections remain a long way off.”
In other words: Scenario E is aspirational, not a default trajectory. Suggesting it as such understates the risks we face and arguably represents an even stronger form of “techno-optimism” than exploring geoengineering research itself.
Further, any relevant estimate on how we could still reach Paris Agreement targets needs to consider the current geopolitical landscape and social trends. It is clear, we have so far failed to communicate what climate change means and we need to work harder for ambitious decarbonisation efforts to be achieved with democratic support. Considering the ongoing scientific debate on the acceleration of global warming², we should also seriously study potential complementing climate intervention measures if minimizing suffering is in our interests.
3. An assessment on geoengineering methods should also consider their potential benefits along with risks.
Evaluating interventions without seriously considering their benefits is not a fair assessment.
Pointing out that deployment of geoengineering is not likely until around mid-century is in line with our understanding – especially considering large-scale interventions.
Around mid-century:
The Arctic Ocean is forecasted to be experiencing its first blue-ocean events, with many key species on the brink of extinction, as these scientists certainly know.
The AMOC could be nearing its tipping point, which according to leading oceanographer Stefan Rahmstorf is a “disaster we must avoid at all cost”. Meanwhile, SRM modeling studies are clearly showing a strengthening AMOC and increased sea ice extent compared to scenarios without it³,⁴.
Worsening permafrost thaw will be locking in remarkable GHG-emissions for decades or centuries to come. (SAI could mitigate this too⁵.)
The Amazon rainforest could be close to reaching its tipping point, transforming much of the forest to a savannah like state.
Heat waves, intensified storms, desertification, intensification of the hydrological cycle, and the rest of the more linear impacts of global warming will be actively impacting the lives of billions of people.
Surely interventions would still be relevant if a deployment would be considered around mid-century, even if interventions are unlikely to offer any climate stabilisation until that time? Perhaps SRM could aid CDR in bringing temperatures down in the second half of the 21st century? On the other hand, if GHG emissions have not been mitigated properly by mid-century time, and the “proven to work” strategy of Siegert et al. has failed, future generations will be left with very limited options, having put all eggs in the fast mitigation-basket.
Furthermore, if climate sensitivity, by a strike of bad luck perhaps, happens to be at the higher end of the spectrum⁶,⁷, putting humanity on track for mass extinction type temperatures, will you not feel safer knowing that interventions, although imperfect, are being studied?
Regardless of the Earth’s true climate sensitivity, the GHG-scenario humanity ends up following, or the timeline for interventions, we should assess interventions based on their potential ability to make dangerous climate change less dangerous as complementary measures in a comprehensive and adaptive climate strategy.
4. Negative impacts of interventions should ideally be displayed in proportion to their scale.
Negative side effects of interventions should be portrayed in a way that gives the public a chance to understand the actual scale of these impacts. Listing negative impacts – such as ozone loss (more likely a delay in ozone recovery or even an increase⁸ in the Arctic?), acid rains (marginal compared with contemporary and historical SO2-emissions⁹), or a shift in the ITCZ (Intertropical Convergence Zone) due to single-hemisphere SAI-deployment (which no one is proposing) – without providing a sense of scale leaves readers to imagine the seriousness of these impacts by themselves. This is likely to mislead readers away from what the research papers actually state about the magnitude of these effects. It’s also worth noting that a true threat of a southern shift of the ITCZ comes from the risk of AMOC collapse or weakening, which could potentially be mitigated with SRM³,⁴, as a supplementary measure to rapid mitigation.
The source cited9 to confirm ozone depletion in Siegert et al. is modeling a hypothetical scenario with two 10-year model runs with 8Mt/y SO2-injections in 2016 climatic conditions, and it concludes the following:
Under sulfate SAI, total column ozone decreases by ~15% at high latitudes and ~5% in the tropics, allowing ~1.6% more UV into the troposphere. That extra UV accelerates tropospheric O₃ photolysis (+20%), boosts OH (+9%), and shortens methane lifetime (-8%), which lowers surface ozone globally. Accounting for these feedbacks, the study estimates ~67,000 fewer ozone-attributable deaths per year, partly offset by ~6,400 additional PM2.5 deaths (notably in India) and ~1,000 additional UV deaths, for a net decline of ~60,000 deaths per year in their representative scenario. In other words, the very paper used to highlight the ozone concern simultaneously reports a net global health benefit via reduced tropospheric ozone under the modeled SAI setup.
We would say SAI is still well worth a thorough risk analysis, also based on the sources Siegert et al. cite.
5. Continued, transparent and inclusive research on different climate interventions is in line with the precautionary principle, and remains crucial to give people agency to take part in decision-making in a meaningful way.
One assessment is not enough to cover such a complex range of emerging climate intervention methods while scientific debate is still going on. We need to understand different approaches better and doing this research now will allow us to make informed decisions in the future. It is not the time to stop research, but to learn what can be done to mitigate the damage that has already been locked in for young people and other climate vulnerable groups for example in the Arctic area.
We encourage everyone to engage with the current reality as uncomfortable as it is. Weaponizing uncertainty and undermining research is not the way if we wish to come together to respond to the growing threat of global warming.
Respectfully,
Operaatio Arktis
References
Siegert, M. et al. (2025). Safeguarding the polar regions from dangerous geoengineering: a critical assessment of proposed concepts and future prospects. Frontiers in Science. Vol 3. https://doi.org/10.3389/fsci.2025.1527393
Rogelj, J. et al. (2023). Credibility gap in net-zero climate targets leaves world at high risk.Science. 380. 1014-1016. DOI:10.1126/science.adg6248
Tilmes, S., MacMartin, D. G., Lenaerts, J. T. M., van Kampenhout, L., Muntjewerf, L., Xia, L., Harrison, C. S., Krumhardt, K. M., Mills, M. J., Kravitz, B., & Robock, A. (2020). Reaching 1.5 and 2.0 °C global surface temperature targets using stratospheric aerosol geoengineering. Earth System Dynamics, 11(3), 579–601. https://doi.org/10.5194/esd-11-579-2020
Xie, M., Moore, J. C., Zhao, L., Wolovick, M., & Muri, H. (2022). Impacts of three types of solar geoengineering on the Atlantic Meridional Overturning Circulation. Atmospheric Chemistry and Physics, 22(7), 4581–4597. https://doi.org/10.5194/acp-22-4581-2022
Chen, Y., Liu, A. & Moore, J.C. Mitigation of Arctic permafrost carbon loss through stratospheric aerosol geoengineering. Nat Commun 11, 2430 (2020). https://doi.org/10.1038/s41467-020-16357-8
Hansen, J. E., Kharecha, P., Sato, M., Tselioudis, G., Kelly, J., Bauer, S. E., … Pokela, A. (2025). Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed? Environment: Science and Policy for Sustainable Development, 67(1), 6–44. https://doi.org/10.1080/00139157.2025.2434494
Jiang X, Su H, Jiang JH, Neelin JD, Wu L, Tsushima Y, Elsaesser G. Muted extratropical low cloud seasonal cycle is closely linked to underestimated climate sensitivity in models. Nat Commun. 2023 Sep 11;14(1):5586. doi: 10.1038/s41467-023-41360-0. PMID: 37696809; PMCID: PMC10495370.
Tilmes, S., Visioni, D., Jones, A., Haywood, J., Séférian, R., Nabat, P., Boucher, O., Bednarz, E. M., & Niemeier, U. (2022). Stratospheric ozone response to sulfate aerosol and solar dimming climate interventions based on the G6 Geoengineering Model Intercomparison Project (GeoMIP) simulations. Atmospheric Chemistry and Physics, 22(7), 4557–4579. https://doi.org/10.5194/acp-22-4557-2022
Samuels-Crow, K., & Irvine, P. (2024, November 26). Would stratospheric aerosol injection add to acid rain? SRM360. https://srm360.org/article/would-sai-add-to-acid-rain/