This chapter explores the evidence on the unique challenges and opportunities posed by climate change. It considers the additional important aspect of the international context associated with climate change, but also more comprehensive strategies and policies that treat mobile and stationary sources together in a way that enhances the cost-effectiveness of the policy approach. The chapter focuses on mitigation and adaptation. The most significant mitigation strategy deals with our use of fossil-fuel energy and examines the negotiations aimed at reducing ozone-depleting gases broke the ice. Fortunately, economic analysis of the climate change problem not only defines the need for action, but also sheds light on effective forms that action might take. The first global pollutant problem confronted by the international community arose when ozone-depleting gases were implicated in the destruction of the stratospheric ozone shield that protects the earth's surface from harmful ultraviolet radiation.