This chapter provides the fundamentals of the relation between energy and climate change, presenting: (i) The scientific evidence that climate change is occurring; (ii) How human use of energy resources contributes to climate change; (iii) How current patterns in global energy use are expected to affect future levels of greenhouse gas emissions. It then outlines the current and expected future impacts of climate change, and presents strategies that can be followed to both mitigate and adapt to the worst expected impacts. To conclude, the chapter discusses the global institutional process to respond to climate, including successes and remaining challenges.