WHAT IS GEOENGINEERING AND STRATOSPHERIC AEROSOL INJECTION (SAI)?

Geoengineering: The United Kingdom’s Royal Society defines geoengineering as “deliberate large-scale intervention in the earth’s climate system, in order to moderate global warming.”

Stratospheric Aerosol Injection (SAI): A research article from Proceedings of the National Academy of Sciences of the United States of America defines Stratospheric Aerosol Injection (SAI) as,“the theoretical deployment of particles in the stratosphere to enhance reflection of incoming solar radiation—is one strategy to slow, pause, or reverse global warming.”

WHY WE NEED TO RESEARCH STRATOSPHERIC AEROSOL INJECTION (SAI)

More research, in general, is needed to understand the verifiability and the consequences of SAI, which are critical before this strategy can be implemented.

  • Because processes are idealized, simplified, and approximated in computer model studies, more precise measurements and models about SAI and its potential to benefit or harm the planet are needed.

  • Better models and better understanding of their limitations would produce more confidence in predictions.

  • Gaps in observational knowledge are a critical barrier to application.

  • Recommended research of clouds and aerosols in particular and their role in the climate system is needed, which requires complex simulation via computing power.

  • A variety of other climate components that have as yet been almost entirely neglected need more attention such as: impacts on ocean circulations; consequences to ecosystems from possible UV-B changes; dynamic influences of the stratosphere on the troposphere which in turn have profound influence on high-latitude response, i.e., sea ice and glaciers and changes to precipitation patterns remain a particular challenge.

  • Develop experiments at the correct scale to test the models and to have the tools available to observe critical components of SAI.

  • Planetary planning institutions to govern this strategy are lacking and need to be developed.

RISKS AND BENEFITS OF STRATOSPHERIC AEROSOL INJECTION (SAI)

THE RISKS

Risks may be large: As a category within geoengineering, Stratospheric Aerosol Injection (SAI), is a relatively simple and inexpensive technology modeled after natural processes such as volcanic action, and readier to be used than other proposed geo-engineering technologies. However, there are also risks that must be better understood, many of which are important issues of governance.

  • Regional effects may include disruption of seasonal monsoonal rains, affecting food production.

  • The potential for:

    • Damaging shifts in rainfall patterns: (Robock et al., 2009)

    • Reduction of Ozone (Keith, 2013)

    • Drought

    • Migration shifts due to weather patterns (Robock et al., 2009).

    • Well-being effects due to loss of blue skies (Robock et al., 2009).

  • Hi-jacking of technology for harmful reasons ie. Suppresses effects of CO2 which could be used by the oil industry to continue production.

  • Positive effects could discourage a timely transition to renewable energy.

  • Simple and inexpensive technology: other countries can (and will) use this (16 countries capable of deployment in future).

  • Once started SAI must be maintained to avoid risk of “termination shock” following abrupt termination of SAI deployment could be significant (Kosgui, 2011).

  • Other countries benefit by others' paying for deployment (unfair).

  • Detail of delivery mechanisms to be finalized.

  • No appropriate Governance tools are available for a technology of planetary scale effects (Shepherd 2012b) .

  • Due to global dispersion and effects, the likeliness of international governance and agreement is slim (look where we are now).

THE BENEFITS

Benefits may be large: The warming atmosphere is the root cause of violent storms, sea level rise, the melting of the Arctic and Antarctic, and irregularity of climate, resulting in food instability and water shortage, social instability, mass migrations and possibly war. Ultimately, if "business as usual" trajectories are not immediately checked, humanity, itself, is at risk.

SAI is the only plausible tool that can buy us time to transition to renewables and to develop other technologies. SAI is the only feasible technology that can address social equity at a mass level, as poorer nations (south of the Equator) will be the first to sustain the effects of climate change while not causative to climate change. As the only technology presently "on the table" which can offer such major global benefits, it is an option that we must explore.

  • High potential for effectiveness, Capable of delivering planetary cooling within one year (Keith, 2013).

  • Technology is simple, inexpensive, and effective.

  • Low cost of SAI, compared to other geoengineering measures.

  • Cancelling the effects of a doubling of GHG concentrations would cost L25-50 billion (Crutzen).

  • The functioning of aerosols in the atmosphere is understood from studies of volcanic eruptions (Long et al., 2011).

  • Aircraft can deploy at scale (Morton, 2015).

  • Stops polar icecap, glacier and snow melts, thus avoiding massive agricultural disruption.

  • Brings down global temperatures to pre-industrial level for comfort.

  • Creates a healthier environment for humans, as we are not able to adapt to high temperatures.

  • A restructuring of global energy supply systems would not be required (Keith, 2013).

  • Restores a more stable climate, thus restoring agriculture which will provide food and economies, especially in the Global South countries that are based on agricultural economies.

  • Stops glacial melting, stops floods and landslides, and glaciers will remain cold over winters, so spring ice-melt can irrigate agricultural fields and provide drinking water.

  • Restores temperatures so that global biodiversity can regenerate and stops the expansion of vector borne diseases.

  • Cools the oceans thus saving ocean biodiversity (however it cannot remove ocean acidification caused by emissions).

  • Reduction of heat will help stop wildfires and most severe weather events.

  • Reduces permafrost melt and the risk of methane release.

  • Avoids drought (Africa, Middle East, Central China).

  • Avoids continuation of 6th Great Extinction (all "large" mammals, amphibians, coral, phytoplankton etc. by 2050).

  • Potential for accelerated plant growth and food production (Morton, 2015).

  • Provides global social equity by providing natural resources, such as food, water and economies, for the most vulnerable and least culpable societies in the world (all south of the Equator).

  • Avoids mass migration and social disruption (Climate Wars).

SAI needs to be implemented in a symmetrical way across the globe for most positive effects for all regions. If one state actor used it unilaterally for its own benefits, the side effects could be very negative and severe on other regions. With SAI it is assumed that continuous maintenance of the particles will be necessary by regular injections over time. Also requires careful gradual cessation when its use needs to end. Rapid cessation will have very detrimental effects causing the temperature to rise rapidly again.

SAI implementation requires greater international global cooperation to be implemented properly than has ever previously been attempted. Because of the potential for unequal global impacts and its potential to be weaponized, this climate intervention strategy carries extremely difficult challenges for governance. Countries are starting to discuss the possibility of funding further research. Ensuring that all peoples and parties are included in representation for decisions about the implementation of SAI will be a complex challenge.

The risks of severe impacts with an abrupt termination increase with the magnitude of SAI employed. Human history has no precedent for the maintenance, over a long timescale, of a technological intervention at the global scale and sophistication comparable to SAI.

A POLITICAL FIGHT FOR RESEARCHING SAI

Further research into SAI as a cooling strategy, requires complex computer modelling of interactive patterns and systems, including cloud properties, transport of heat by ocean and atmospheric circulations, various complex regional feedbacks, and top-of-atmosphere fluxes. Idealized simulation studies bypass the modeling of this complex chain of events. The real system has far greater complexity than does any model, and thus no model, yet, of this system can provide a quantitatively reliable detailed prediction of how Earth will respond to this occurrence.

For this and other reasons, The Royal society (2009) rejected strategies requiring millennial dependence upon albedo modification techniques, like SAI, finding that it should only be applied for a limited time accompanied by aggressive programs of conventional mitigation and/or CDR so that their use would be discontinued with certainty in near futures. No well-documented field experiments involving controlled emissions of SAI have yet been conducted. Studies of volcanic eruptions offer the only feasible large-scale opportunities to examine stratospheric attenuation of solar energy. Even though there are many differences between a single pulse from volcanoes, and what will be required with SAI, volcanic eruptions still provide the best opportunity to test and improve understanding of the relevant physical processes.

At present, it is not clear whether a small field experiment involving injection of substances into the stratosphere could resolve the outstanding scientific questions without being of a scale large enough to be considered as deployment. Corresponding, clear, transparent guidelines and deliberative process to address these issues is necessary. (Carbon Brief.14.11.2017)