Solar geoengineering could reduce climate change, but poses risks. This volume explores how it is, could, and should be governed.

Climate change is among the world's most important problems, and solutions based on emission cuts or adapting to new climates remain elusive. One set of proposals receiving increasing attention among scientists and policymakers is 'solar geoengineering', (also known as solar radiation modification) which would reflect a small portion of incoming sunlight to reduce climate change. Evidence indicates that this could be effective, inexpensive, and technically feasible, but it poses environmental risks and social challenges. Governance will thus be crucial. In The Governance of Solar Geoengineering, Jesse L. Reynolds draws on law, political science, and economics to show how solar geoengineering is, could, and should be governed. The book considers states' incentives and behavior, international and national law, intellectual property, compensation for possible harm, and non-state governance. It also recommends how solar geoengineering could be responsibly researched, developed, and - if appropriate - used in ways that would improve human well-being and ensure sustainability.

The National Research Council report Climate Intervention: Reflecting Sunlight to Cool Earth (NRC, 2015) reviewed the state of the science and provided high-level findings and recommendations regarding SG methods. This current study was tasked to update the 2015 assessment of the state of understanding and to provide recommendations for how to establish a research program, what to encompass in the research agenda, and what mechanisms to employ for governing this research.

The sobering reality of the disconnect between the resolve of the world community to effectively address climate change, and what actually needs to be done, has led to increasing impetus for consideration of a suite of approaches collectively known as “climate geoengineering,” or “climate engineering.” Indeed, the feckless response of the world community to climate change has transformed climate geoengineering from a fringe concept to a potentially mainstream policy option within the past decade. This volume will explore scientific, political and legal issues associated with the emerging field of climate geoengineering. The volume encompasses perspectives on both of the major categories of climate geoengineering approaches, carbon dioxide removal and solar radiation management.

The growing problem of changing environmental conditions caused by climate destabilization is well recognized as one of the defining issues of our time. The root problem is greenhouse gas emissions, and the fundamental solution is curbing those emissions. Climate geoengineering has often been considered to be a "last-ditch" response to climate change, to be used only if climate change damage should produce extreme hardship. Although the likelihood of eventually needing to resort to these efforts grows with every year of inaction on emissions control, there is a lack of information on these ways of potentially intervening in the climate system. As one of a two-book report, this volume of Climate Intervention discusses albedo modification - changing the fraction of incoming solar radiation that reaches the surface. This approach would deliberately modify the energy budget of Earth to produce a cooling designed to compensate for some of the effects of warming associated with greenhouse gas increases. The prospect of large-scale albedo modification raises political and governance issues at national and global levels, as well as ethical concerns. Climate Intervention: Reflecting Sunlight to Cool Earth discusses some of the social, political, and legal issues surrounding these proposed techniques. It is far easier to modify Earth's albedo than to determine whether it should be done or what the consequences might be of such an action. One serious concern is that such an action could be unilaterally undertaken by a small nation or smaller entity for its own benefit without international sanction and regardless of international consequences. Transparency in discussing this subject is critical. In the spirit of that transparency, Climate Intervention: Reflecting Sunlight to Cool Earth was based on peer-reviewed literature and the judgments of the authoring committee; no new research was done as part of this study and all data and information used are from entirely open sources. By helping to bring light to this topic area, this book will help leaders to be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.

The first book to focus on the legal aspects of climate engineering, making recommendations for future laws and governance.

Stabilizing the world’s climates means cutting carbon dioxide pollution. There’s no way around it. But what if that’s not enough? What if it’s too difficult to accomplish in the time allotted or, worse, what if it’s so late in the game that even cutting carbon emissions to zero, tomorrow, wouldn’t do? Enter solar geoengineering. The principle is simple: attempt to cool Earth by reflecting more sunlight back into space. The primary mechanism, shooting particles into the upper atmosphere, implies more pollution, not less. If that doesn’t sound scary, it should. There are lots of risks, unknowns, and unknowables. In Geoengineering: The Gamble, climate economist Gernot Wagner provides a balanced take on the possible benefits and all-too-real risks, especially the so-called “moral hazard” that researching or even just discussing (solar) geoengineering would undermine the push to cut carbon emissions in the first place. Despite those risks, he argues, solar geoengineering may only be a matter of time. Not if, but when. As the founding executive director of Harvard’s Solar Geoengineering Research Program, Wagner explores scenarios of a geoengineered future, offering an inside-view of the research already under way and the actions the world must take to guide it in a productive direction.

In this book, eleven prominent authorities on climate change consider the legal, policy, and philosophical issues presented by geoengineering. The book asks: When, if ever, are decisions to embark on potentially risky climate modification projects justified? If such decisions can be justified, in a world without a central governing authority, who should authorize such projects and by what moral and legal right?

The Royal Society has published the findings of a major study into geoengineering the climate. The study, chaired by Professor John Shepherd FRS, was researched and written over a period of twelve months by twelve leading academics representing science, economics, law and social science. Man-made climate change is happening and its impacts and costs will be large, serious and unevenly spread. The impacts may be reduced by adaptation and moderated by mitigation, especially by reducing emissions of greenhouse gases. However, global efforts to reduce emissions have not yet been sufficiently successful to provide confidence that the reductions needed to avoid dangerous climate change will be achieved. This has led to growing interest in geoengineering, defined here as the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change. However, despite this interest, there has been a lack of accessible, high quality information on the proposed geoengineering techniques which remain unproven and potentially dangerous. This study provides a detailed assessment of the various methods and considers the potential efficiency and unintended consequences they may pose. It divides geoengineering methods into two basic categories: 1. Carbon Dioxide Removal (CDR) techniques, which remove CO2 from the atmosphere. As they address the root cause of climate change, rising CO2 concentrations, they have relatively low uncertainties and risks. However, these techniques work slowly to reduce global temperatures. 2. Solar Radiation Management (SRM) techniques, which reflect a small percentage of the sun's light and heat back into space. These methods act quickly, and so may represent the only way to lower global temperatures quickly in the event of a climate crisis. However, they only reduce some, but not all, effects of climate change, while possibly creating other problems . They also do not affect CO2 levels and therefore fail to address the wider effects of rising CO2, including ocean acidification. The report recommends: Parties to the UNFCCC should make increased efforts towards mitigating and adapting to climate change and in particular to agreeing to global emissions reductions of at least 50% on 1990 levels by 2050 and more thereafter; CDR and SRM geoengineering methods should only be considered as part of a wider package of options for addressing climate change. CDR methods should be regarded as preferable to SRM methods. Relevant UK government departments, in association with the UK Research Councils, should together fund a 10 year geoengineering research programme at a level of the order of £10M per annum. The Royal Society, in collaboration with international science partners, should develop a code of practice for geoengineering research and provide recommendations to the international scientific community for a voluntary research governance framework. The Royal Society issued a call for submissions and convened a small ethics workshop as part of the evidence gathering process. More information is available in the main report.

A leading scientist argues that we must consider deploying climate engineering technology to slow the pace of global warming. Climate engineering—which could slow the pace of global warming by injecting reflective particles into the upper atmosphere—has emerged in recent years as an extremely controversial technology. And for good reason: it carries unknown risks and it may undermine commitments to conserving energy. Some critics also view it as an immoral human breach of the natural world. The latter objection, David Keith argues in A Scientist's Case for Climate Engineering, is groundless; we have been using technology to alter our environment for years. But he agrees that there are large issues at stake. A leading scientist long concerned about climate change, Keith offers no naïve proposal for an easy fix to what is perhaps the most challenging question of our time; climate engineering is no silver bullet. But he argues that after decades during which very little progress has been made in reducing carbon emissions we must put this technology on the table and consider it responsibly. That doesn't mean we will deploy it, and it doesn't mean that we can abandon efforts to reduce greenhouse gas emissions. But we must understand fully what research needs to be done and how the technology might be designed and used. This book provides a clear and accessible overview of what the costs and risks might be, and how climate engineering might fit into a larger program for managing climate change.