Geoengineering is the deliberate modification of the climate system. It has been discussed as a technique to counteract changes expected as a result of Anthropogenic Global Warming (AGW).¹ Speculation has occurred that the possibility of geoengineering will reduce or delay efforts to mitigate AGW. This possible delay or reduction in mitigation has been described as ‘moral hazard’ by various authors. We investigate the definitions and use of the term ‘moral hazard’, and the related (but significantly different) concept of ‘morale hazard’, in relevant law, economic and insurance literatures. We find that ‘moral hazard’ has been generally misapplied in discussions of geoengineering, which perhaps explains unexpected difficulties in detecting expected effects experimentally.² We clarify relevant usage of the terms, identifying scenarios that can properly be described as moral hazard (malfeasance), and morale hazard (lack of caution or recklessness). We note generally the importance of correctly applying this distinction when discussing geoengineering. In conclusion, we note that a proper consideration of the risks of both moral and morale hazards allows us to easily segment framings for both geoengineering advocacy and the advocate groups who rely on these framings. We suggest mnemonics for groups vulnerable to moral hazard (Business as Usuals) and morale hazard (Chicken Littles) and suggest the development of an experimental methodology for validating the distinction thus drawn.

Geoengineering is a proposed response to anthropogenic global warming (AGW). Conventionally it consists of two strands: Solar Radiation Management (SRM), which is fast-acting, incomplete but inexpensive, and Carbon Dioxide Removal (CDR), which is slower acting, more expensive, and comprehensive. Pairing SRM and CDR offers a contractually complete solution for future emissions if effectively-scaled and coordinated. SRM offsets warming, while CDR takes effect.We suggest coordination using a blockchain, i.e. smart contracts and a distributed ledger. Specifically, we integrate CDR futures with time and volume-matched SRM orders, to address emissions contractually before release. This provides an economically and environmentally proportionate solution to CO2 emissions at the wellhead, with robust contractual transparency, and minimal overhead cost. Our proposal offers a ‘polluter pays’ implementation of Long & Shepherds SRM ‘bridge’ concept. This ‘polluter geoengineers’ approach mandates and verifies emissions-linked payments with minimal friction, delay, or cost. Finally, we compare alternative market designs against this proposal, finding that this proposal offers several advantages. We conclude that blockchain implementation of the ‘polluter geoengineers’ approach is attractive and feasible for larger wellhead contracts. We also identify a handful of advantages and disadvantages that merit further study.

Solar Radiation Management (SRM) geoengineering is a proposed response to anthropogenic global warming (AGW). Stratospheric aerosol injection (SAI) is one proposed method, reliant on lofting material into the stratosphere. Engineering reviews related to this technology approach have been sparse, with most major primary analyses now at least five years old. We attempt to bridge this gap—with a short, qualitative review of recent developments in various fields of engineering that have potential applicability to SAI. Our analysis shows that a new conventional aircraft design is still likely to be the most dependable and affordable technology solution (cost estimates start around $1000–1500 per ton lofted), with hybrid or vacuum airships a potential challenger. Rockets, gas guns and MAGLEV/coilguns show some potential—although they lack the inherent level-flight capability that would be needed for direct aerosol distribution (versus distribution of gaseous precursors), without substantial additional engineering. Should very high-altitude access be required, rockets, jet-hybrid rockets, and various guns (especially light-gas guns) potentially offer the required capability. Costs and performance for tethered balloons remain highly uncertain. Towers are not found to be promising. The extreme accessibility of free balloons suggests that this method may be used primarily for reasons of political leverage, as opposed to being an optimal engineering solution.

Futures contracts are exchange-traded financial instruments that enable parties to fix a price in advance, for later performance on a contract. Forward contracts also entail future settlement, but they are traded directly between two parties. Futures and forwards are used in commodities trading, as producers seek financial security when planning production. We discuss the potential use of futures contracts in Carbon Dioxide Removal (CDR) markets; concluding that they have one principal advantage (near-term price security to current polluters), and one principal disadvantage (a combination of high price volatility and high trade volume means contracts issued by the private sector may cause systemic economic risk). Accordingly, we note the potential for the development of futures markets in CDR, but urge caution about the prospects for market failure. In particular, we consider the use of regulated markets: to ensure contracts are more reliable, and that moral hazard is minimised. While regulation offers increased assurances, we identify major insufficiencies with this approach—finding it generally inadequate. In conclusion, we suggest that only governments can realistically support long-term CDR futures markets. We note existing long-term CDR plans by governments, and suggest the use of state-backed futures for supporting these assurances.

Solar geoengineering, also known as Solar Radiation Modification (SRM), has been proposed to alter Earth’s radiative balance to reduce the effects of anthropogenic climate change. SRM has been identified as a research priority, as it has been shown to effectively reduce surface temperatures, while substantial uncertainties remain around side effects and impacts. Global modeling studies of SRM have often relied on idealized scenarios to understand the physical processes of interventions and their widespread impacts. These extreme or idealized scenarios are not directly policy-relevant and are often physically implausible (such as imposing global solar reduction to counter the warming of an instantaneous quadrupling of CO2). The climatic and ecological impacts of politically relevant and potentially plausible SRM approaches have rarely been modeled and assessed. Nevertheless, commentators and policymakers often falsely assume that idealized or extreme scenarios are proposed solutions to climate change. This paper proposes 18 scenarios that appear to be broadly plausible from political and Earth System perspectives and encompass futures that could be both warnings or perhaps desirable. We place these scenarios into four groups following broader strategic contexts: (1) Global Management; (2) Regional Emergencies; (3) Coordinated Regional Interventions; and (4) Reactive Global Interventions. For each scenario, relevant model experiments are proposed. Some may be performed with existing setups of global climate models, while others require further specification. Developing and performing these model experiments – and assessing likely resulting impacts on society and ecosystems – would be essential to inform public debate and policymakers on the real-world issues surrounding SRM.