Climate change is occurring, is caused largely by human activities, and poses significant risks for-and in many cases is already affecting-a broad range of human and natural systems. The compelling case for these conclusions is provided in Advancing the Science of Climate Change, part of a congressionally requested suite of studies known as America's Climate Choices. While noting that there is always more to learn and that the scientific process is never closed, the book shows that hypotheses about climate change are supported by multiple lines of evidence and have stood firm in the face of serious debate and careful evaluation of alternative explanations. As decision makers respond to these risks, the nation's scientific enterprise can contribute through research that improves understanding of the causes and consequences of climate change and also is useful to decision makers at the local, regional, national, and international levels. The book identifies decisions being made in 12 sectors, ranging from agriculture to transportation, to identify decisions being made in response to climate change. Advancing the Science of Climate Change calls for a single federal entity or program to coordinate a national, multidisciplinary research effort aimed at improving both understanding and responses to climate change. Seven cross-cutting research themes are identified to support this scientific enterprise. In addition, leaders of federal climate research should redouble efforts to deploy a comprehensive climate observing system, improve climate models and other analytical tools, invest in human capital, and improve linkages between research and decisions by forming partnerships with action-oriented programs.

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

Climate change is increasingly recognized as a global threat, and is already contributing to record-breaking hurricanes and heat waves. To prevent the worst impacts, attention is now turning to climate engineering - the intentional large-scale modification of the environment to reduce the impact of climate change. The two principal methods involve removing some carbon dioxide from the atmosphere (which could consume huge amounts of land and money, and take a long period of time), and reducing the amount of solar radiation reaching the earth's surface, perhaps by spraying aerosols into the upper atmosphere from airplanes (which could be done quickly but is risky and highly controversial). This is the first book to focus on the legal aspects of these technologies: what government approvals would be needed; how liability would be assessed and compensation provided if something goes wrong; and how a governance system could be structured and agreed internationally.

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.

Policymakers have raised questions about geoengineering (GE) -- large-scale deliberate interventions in the earth's climate system to diminish climate change or its impacts -- and its role in a broader strategy of mitigating and adapting to climate change. Most GE proposals fall into 2 categories: carbon dioxide removal, which would remove carbon dioxide from the atmosphere, and solar radiation management, which would offset temperature increases by reflecting sunlight back into space. This report examined: (1) the state of GE science; (2) federal involvement in GE; and (3) the views of experts and federal officials about the extent to which federal laws and international agreements apply to GE, and any governance challenges. A print on demand pub.