Solar Geoengineering

This page is about the intersection of solar geoengineering and machine learning. For an overview of solar geoengineering as a whole, please see the Wikipedia page on this topic.

Solar geoengineering (also known as "solar radiation management") refers of proposals aimed at increasing the amount of heat the Earth releases, in order to counteract global warming caused by the greenhouse effect. In particular, solar geoengineering proposals seek to "reflect a small fraction of sunlight back into space or increase the amount of solar radiation that escapes back into space to cool the planet." Examples of such proposals include attempting to make clouds brighter so they reflect back more sunlight, installing sun shields in space, and scattering aerosols into the stratosphere in order to scatter a small amount of sunlight.

It is worth noting that solar geoengineering proposals come with many uncertainties and risks (regarding both implementation and effects), as well as governance challenges and ethical considerations. In addition, since solar geoengineering proposals do not address the amount of CO₂ or other greenhouse gases in the atmosphere, they do not necessarily address issues related to rising CO₂ levels, such as ocean acidification. As a result, solar geoengineering proposals are widely considered to be very much a "last resort" for addressing climate change.

Although it has been argued that the "hardest and most important problems raised by solar geoengineering are non-technical," there are a number of technical problems that remain to be addressed, some of which may (speculatively) benefit from machine learning.

Machine Learning Application Areas

There are a number of speculative applications of machine learning to solar geoengineering. (For more details on these problem areas, see the chapter on Solar Geoengineering in the paper "Tackling Climate Change with Machine Learning.")

• Designing aerosols: Many solar geoengineering proposals rely on injecting aerosol particles into the atmosphere to partially reflect sunlight. ML can (speculatively) accelerate the search for new aerosols that are chemically nonreactive but still reflective, cheap, and easy to keep aloft. See also the page on accelerated science.
• Modeling aerosols: Many solar geoengineering proposals rely on injecting aerosol particles into the atmosphere to partially reflect sunlight, but their physics is not fully understood. ML can help speed up physical models and quantify the uncertainty of predictions. See also Fletcher et al. (2018) for a discussion on how uncertainties in aerosol model affect our models of climate change, as well as the page on climate science.
• Engineering a planetary control system: Controlling a geoengineering system comes with a multitude of challenges and a host of possible side effects, many of which could be catastrophic. Speculatively, ML can help fine-tune geoengineering interventions by suggesting control actions and emulating the complex dynamical systems involved. See also MacMartin and Kravitz (2019) for a deeper discussion of the "engineering design aspects of climate engineering."
• Modeling geoengineering impacts: It remains unclear what consequences will result from geoengineering proposals such as injecting aerosols into the stratosphere. ML can help model the impact of aerosols on human health, the effect of diminished light on agriculture, and other potential consequences of solar geoengineering. See Irvine et al. (2016) for a review of the literature on solar geoengineering impacts, and Proctor et al. (2018) for an analysis of the effects of stratospheric sulfate aerosols created by historical volcanic eruptions. See also the discussion on integrated assessment models on the public policy and decision science page.

Background Readings

• Governance of the Deployment of Solar Geoengineering (2018): A comprehensive report is based on a workshop organized and hosted by the Harvard Project on Climate Agreements. Available here.
• An Overview of the Earth System Science of Geoengineering (2016): An introductory article regarding approaches in geoengineering and the considerations to take into account. Available here.
• Towards a comprehensive climate impacts assessment of solar geoengineering (2016): A paper exploring the impacts of solar geoengineering on natural and human systems such as agriculture, health, water resources, and ecosystem. Available here.
• The Engineering of Climate Engineering (2019): A review of "the engineering design aspects of climate engineering," discussing both progress to date and remaining challenges that will need to be addressed. Available here.
• Quantifying uncertainty from aerosol and atmospheric parameters and their impact on climate sensitivity (2018): A quantitative assessment of how uncertainties in aerosol modeling and atmospheric parameters affect climate models' ability to accurately simulate global temperature change. Available here.
• Estimating global agricultural effects of geoengineering using volcanic eruptions (2018): An assessment of the effects on stratospheric sulfate aerosols on crop yields based on historical volcanic eruption data, as a step towards understanding the effects of solar radiation management techniques. Available here.

Online Courses and Course Materials

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Conferences, Journals, and Professional Organizations

Major conferences

• Climate Engineering Conference: An annual conference bringing together the research, policy, and civic communities to discuss the highly complex and interlinked ethical, social and technical issues related to climate engineering. Website here.
• American Geophysical Union (AGU) Fall Meeting: The annual meeting of the American Geophysical Union, presenting thematic research on the latest topics in geophysical sciences. Website here.

Major journals

• Journal of Geophysical Research: Atmospheres: A journal publishing original research articles that advance and improve the understanding of atmospheric properties and processes, including the interaction of the atmosphere with other components of the Earth system, as well as their roles in climate variability and change. Website here.
• Atmospheric Chemistry and Physics: An international scientific journal dedicated to the publication and public discussion of high-quality studies investigating the Earth's atmosphere and the underlying chemical and physical processes. Website here.
• Earth's Future: A transdisciplinary journal examining the state of the planet and its inhabitants, sustainable and resilient societies and the science of the Anthropocene. Website here.

Libraries and Tools

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Data

• The Geoengineering Model Intercomparison Project: A resource describing solar geoengineering simulation data. Website here.

Relevant Groups and Organizations

• Harvard's Solar Geoengineering Research Program (SGRP): A group under the Harvard University Center for the Environment that aims to "further critical research on both the science and governance of solar geoengineering" by "advancing science and technology," "assessing efficacy and risks," and "laying out governance options and social implications." Website here.
• Stratospheric Controlled Perturbation Experiment (SCoPEx): A Harvard research project that aims to "to advance understanding of stratospheric aerosols that could be relevant to solar geoengineering" by collecting empirical data on aerosol microphysics and atmospheric chemistry via a high-altitude balloon. Website here.