The primary objective of this report is to provide a tutorial to the climate analysis and decision-making communities on current best practice in describing and analyzing uncertainty in climate-related problems. The report discusses a number of formulations of uncertainty and the various ways in which uncertainty can arise. It introduces several alternative perspectives on uncertainty including both the classical or frequentist view of probability, which defines probability as the property of a large number of repeated trials of some process such as the toss of a coin, and the subjectivist view, in which probability is an indication of degree of belief informed by all available evidence. A distinction is drawn between uncertainty about the value of specific quantities and uncertainty about the underlying functional relationships among key variables. Finally the report addresses a number of issues that arise in communicating about uncertainty. The report includes lessons from both the mitigation and adaptation domain. Reference: Granger Morgan, M., Dowlatabadi, H., Henrion, M., Keith, D., Lempert, R., McBride, S., Small, M. and Wilbanks, T. (Eds.) (2009) Best Practice Approaches for Characterizing, Communicating, and Incorporating Scientific Uncertainty in Decisionmaking, A Report by the Climate Change Science Program and the Subcommittee on Global Change Research. National Oceanic and Atmospheric Administration, Washington, DC, US.