Although addressing greenhouse gases is a leading priority of the President and many members of Congress, the ability to limit these emissions already exists under Clean Air Act authorities that Congress has enacted. In response to the Supreme Court decision, EPA has begun the process of using this existing authority, issuing an "endangerment finding" for greenhouse gases and proposing greenhouse gas (GHG) regulations for new motor vehicles. This book reviews the various options that the EPA could exercise to control GHG emissions from stationary sources under the Act.