2. FAO definition of sustainability “Sustainability is: “Sustainability is: the handling and conservation of natural resources and the handling and conservation of natural resources and the orientation of technological and institutional change the orientation of technological and institutional change so as to ensure the continuous satisfaction of human needs for present and future generations” so as to ensure the continuous satisfaction of human needs for present and future generations”

3. Sustainability Let X t be a vector of ecosystem services (clean water, forest products, food, aesthetics, etc.) in time t Let X t be a vector of ecosystem services (clean water, forest products, food, aesthetics, etc.) in time t The “Natural Capital” of the world The “Natural Capital” of the world Strict sustainability criterion: Every element in X must be the same or greater in the future Strict sustainability criterion: Every element in X must be the same or greater in the future Total Natural Capital does not decrease Total Natural Capital does not decrease Weak sustainability criterion: Weak sustainability criterion: U(X future ) - U(X now ) > 0, where U is utility U(X future ) - U(X now ) > 0, where U is utility In effect, one or more ecosystem services can decrease in abundance, as long as there are appropriate substitutes In effect, one or more ecosystem services can decrease in abundance, as long as there are appropriate substitutes Natural capital -> Economic capital Natural capital -> Economic capital

4. Issues implicit in sustainability Distribution of resources currently (developed versus developing) Distribution of resources currently (developed versus developing) Distribution of resources over time (how much does the future matter?) Distribution of resources over time (how much does the future matter?) The scale of analysis The scale of analysis