This chapter reviews the role of wetlands in the global carbon cycle and global change, outlining the global extent of wetlands, the significant carbon processes in wetlands, particularly methanogenesis, and the estimates on a global scale. It then reviews the effects that global climate change may have on wetlands and discusses the possible feedbacks. The chapter also reviews some management options that may minimize emissions of methane and protect coastal wetlands in the advance of sea level rise. The sulfur cycle is important in some wetlands for the oxidation of organic carbon. The effects of climate change on wetlands can lead to both positive and negative feedbacks in climate change. One example of a possible positive feedback is increased temperatures expected from global change leading to increased emissions of greenhouse gases as a result of increased metabolism. Water level alteration is one of the easiest and most effective ways to control methane emissions from managed wetlands.