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What are the potential risks and benefits of geoengineering the climate?
Executive summary
Geoengineering splits broadly into carbon dioxide removal (CDR) and solar radiation management (SRM); CDR aims to remove greenhouse gases but is often slow and costly, while SRM (for example, stratospheric aerosol injection) can cool the planet rapidly but carries significant regional and ecological risks [1] [2]. Recent reviews and modeling studies warn SRM could disrupt regional climate systems like ENSO, damage the ozone layer, and create political and moral‑hazard dilemmas—while some benefit–cost analyses argue reduced heat mortality might outweigh aerosol side effects in certain scenarios [3] [4] [5] [6].
1. What geoengineering actually covers — two very different toolkits
Geoengineering is an umbrella term for deliberate, large‑scale climate interventions split into carbon dioxide removal (CDR) and solar radiation management (SRM); CDR removes and stores CO2 over years to decades, while SRM aims to reflect sunlight and can change temperatures within years but does not remove greenhouse gases [1] [7]. This distinction matters because the two families of techniques have contrasting timelines, reversibility and risk profiles [1].
2. Potential near‑term benefits: fast cooling vs. slower fixes
SRM methods such as stratospheric aerosol injection can produce rapid, global cooling that could reduce heat‑related deaths and buy time for mitigation and adaptation, and some studies quantify mortality benefits potentially outweighing aerosol harms under certain assumptions [5] [8]. CDR approaches promise durable reduction of CO2 concentrations and are integral to many net‑zero scenarios, providing co‑benefits like carbon storage and, in some cases, biodiversity gains [1] [9].
3. Known physical risks: regional mismatches, weather and chemistry impacts
Climate modeling and empirical reviews show SRM need not affect the planet uniformly: interventions can alter rainfall, monsoons and major climate cycles such as El Niño–Southern Oscillation, with some strategies potentially disrupting ENSO entirely while others have minimal effect—outcomes depend on the method and geography [3] [2]. Sulfate aerosols—often modeled for SRM—can harm stratospheric ozone and increase air‑pollution mortality even as they reduce heat mortality, creating complex trade‑offs [5] [6].
4. Ecological and polar concerns: experiments may backfire
Targeted ideas—like polar sea‑ice thickening, sea curtains or artificial ice—have been reviewed and found either infeasible at scale, prohibitively costly, logistically challenging in harsh environments, or likely to harm polar ecosystems, meaning several proposed regional geoengineering fixes are judged unlikely to save the poles [10] [4]. Those reviews stress that speculative geoengineering could distract resources from proven mitigation and adaptation [10].
5. Political, governance and security risks
Experts warn that any deployment would create transboundary winners and losers, producing geopolitical friction over who decides goals, timing and termination conditions; the security implications extend to competition for strategic regions as climate niches shift [2] [11]. The growth of private, for‑profit actors and venture capital in SRM heightens governance concerns, because commercial incentives can conflict with the need for transparent, multilateral decision‑making [12].
6. Ethical and social dilemmas: moral hazard and public trust
Civil society and some scientists caution that research or the prospect of SRM creates a “moral hazard” by reducing political pressure to cut emissions, and that secretive or corporate‑led efforts could erode public trust and democratic oversight [11] [12]. Public perceptions are mixed: some communities, including in the Global South, show conditional support for limited field tests but also raise concerns about inequity and who bears risks [13].
7. Scientific uncertainty and the call for careful research
Major assessments and modeling papers conclude that many methods remain poorly understood, with potential for limited effectiveness or severe side effects if scaled; commentators urge coordinated, transparent, international research and governance before any deployment [6] [14]. At the same time, some research groups argue benefit–risk calculations justify more study and quantified comparisons with the harms of unabated warming [5].
8. Competing views and where consensus exists
There is no consensus for deployment: some scientists advocate cautious research to reduce uncertainty and prepare decision frameworks, while others say research itself raises the odds of use and could be a distraction from emissions cuts [15] [12]. What reporting does consistently show is agreement that SRM would mask symptoms, not address the root cause of fossil‑fuel emissions, and that emissions reductions remain essential [15] [16].
9. Bottom line for policymakers and the public
Available reporting shows geoengineering offers potential short‑term relief (SRM) and long‑term mitigation tools (CDR) but comes with large, uneven risks—regional climate disruption, ecological harm, governance and ethical problems—and the danger of drawing attention and resources away from decarbonization; experts therefore call for transparent, multilateral research and robust governance before any deployment [2] [16] [14]. Available sources do not mention a single, uncontested pathway that makes geoengineering a safe substitute for cutting emissions.