This report describes the conduct of the cost-benefit analysis of climate proofing investment projects. An important message is that the presence of uncertainty about climate change does not invalidate the conduct of the economic analysis of investment projects, nor does it require a new type of economic analysis. However, the presence of uncertainty does require a different type of decision-making process in which technical and economic expertise combine to present decision makers with the best possible information on the economic efficiency of alternative designs of investment projects.