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 signals are everywhere that our planet is experiencing significant climate change. It is clear that we need to reduce the emissions of carbon dioxide and other greenhouse gases from our atmosphere if we want to avoid greatly increased risk of damage from climate change. Aggressively pursuing a program of emissions abatement or mitigation will show results over a timescale of many decades. How do we actively remove carbon dioxide from the atmosphere to make a bigger difference more quickly? As one of a two-book report, this volume of Climate Intervention discusses CDR, the carbon dioxide removal of greenhouse gas emissions from the atmosphere and sequestration of it in perpetuity. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration introduces possible CDR approaches and then discusses them in depth. Land management practices, such as low-till agriculture, reforestation and afforestation, ocean iron fertilization, and land-and-ocean-based accelerated weathering, could amplify the rates of processes that are already occurring as part of the natural carbon cycle. Other CDR approaches, such as bioenergy with carbon capture and sequestration, direct air capture and sequestration, and traditional carbon capture and sequestration, seek to capture CO2 from the atmosphere and dispose of it by pumping it underground at high pressure. This book looks at the pros and cons of these options and estimates possible rates of removal and total amounts that might be removed via these methods. With whatever portfolio of technologies the transition is achieved, eliminating the carbon dioxide emissions from the global energy and transportation systems will pose an enormous technical, economic, and social challenge that will likely take decades of concerted effort to achieve. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration will help to better understand the potential cost and performance of CDR strategies to inform debate and decision making as we work to stabilize and reduce atmospheric concentrations of carbon dioxide.

Reaching net zero emissions will not be the end of the climate struggle, but only the end of the beginning. For centuries thereafter, temperatures will remain elevated; climate damages will continue to accrue and sea levels will continue to rise. Even the urgent and utterly essential task of reaching net zero cannot be achieved rapidly by emissions reductions alone. To hasten net zero and minimize climate damages thereafter, we will also need massive carbon removal and storage. We may even need to reduce incoming solar radiation in order to lower unacceptably high temperatures. Such unproven and potentially risky climate interventions raise mind-blowing questions of governance and ethics. Pandora's Toolbox offers readers an accessible and authoritative introduction to both the hopes and hazards of some of humanity's most controversial technologies, which may nevertheless provide the key to saving our world.

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.

Reaching net zero emissions will not be the end of the climate struggle, but only the end of the beginning. For centuries thereafter, temperatures will remain elevated; climate damages will continue to accrue and sea levels will continue to rise. Even the urgent and utterly essential task of reaching net zero cannot be achieved rapidly by emissions reductions alone. To hasten net zero and minimize climate damages thereafter, we will also need massive carbon removal and storage. We may even need to reduce incoming solar radiation in order to lower unacceptably high temperatures. Such unproven and potentially risky climate interventions raise mind-blowing questions of governance and ethics. Pandora's Toolbox offers readers an accessible and authoritative introduction to both the hopes and hazards of some of humanity's most controversial technologies, which may nevertheless provide the key to saving our world.

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.