Environmental Decisionmaking

Problem Set #2:

1) (4 pts) Draw a schematic stock-and-flow diagram for the amount of water in a pond. Imagine that the amount of water flowing into that point is not a function of the amount of water in the pond, but that as the amount of water increases, the amount flowing out increases as well. You don't need to include any numbers, just draw the diagram.

2) (4 pts) Think about an animal population colonizing a new island. At first, there is plenty of food available for the animals, and the population explodes, but eventually they fill the island. Draw a very rough plot of what you expect to happen to population in time on this island, beginning with the time of initial colonization. How would you represent this in a stock-and-flow type diagram?

3) (6 pts) Lester Brown is far out of the mainstream in the food-supply debate. Most experts believe that genetic engineering and other technological advances will continue to improve the food situation of the world's hungry. Brown's argument, that it is hard to think of a way that we can meet this growing problem, was made in the 70s and turned out to drastically underestimate the human capacity for innovation. And yet, Brown's arguments are compelling. Discuss Brown's "mental model" in relation to more traditional mental models. What can policymakers use to base decisions on in cases like this?

4) (4 pts) What is the basis of the "Population Surprise" (Singer article)? What is it about the mental models that people used that kept people from thinking about the possibility of "depopulation"? Is depopulation something that should be on our minds at this time?

5) (2 pts) Gallopin and Raskin present what they consider to be possible future outcomes, with the hope of informing public debate. Does this exercise differ from numerical modeling in a fundamental way (if so, why, if not, why not)?