In order to demonstrate that economics is capable of joining the environmental sciences in a seamless way, it will prove useful to begin with a discussion of two issues that are much in the news today. The first is the subject of an acrimonious debate between those who favour free trade and those who are opposed to it on grounds that it often hurts the poorest in Desta’s world. The second is the belief that because the economic effects of carbon dioxide emissions into the atmosphere are likely to be felt by a generation or two further down from us, we needn’t do anything about climate change now.