Many voices, domestic and international, have called upon the United States to increase foreign assistance to address climate change. Proponents maintain that such assistance could help promote low-emissions and high-growth economic development in lower income countries, while simultaneously protecting the more vulnerable countries from the effects of a changing climate. Recent studies estimate the needs for climate change financing in the developing world to range from US$4 billion to several hundred billion annually by the year 2030. This book examines the needs, sources and delivery methods for international climate change financing with a focus on the fundamental dispute concerning who should pay for it and how.