The international community is not taking the action necessary to avert dangerous increases in greenhouse gases. Facing a potentially bleak future, the question that confronts humanity is whether the best of bad alternatives may be to counter global warming through human-engineered climate interventions. 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? If states or private actors undertake geoengineering ventures absent the blessing of the international community, what recourse do the rest of us have?