Ecological economics is the study of the economic value of intact natural systems, and the true (dollar) cost of their destruction. It's an exploding field, but usually pretty dry stuff, downright desicated even. Lissa Harris has done us all a favor by putting together three profiles of leaders in the field which are not only readable, but somewhat entertaining.
"Compared to pork bellies and Palm Pilots, most goods and services provided by the environment are peculiar and ill-behaved: They don't respect property rights, they may take millennia to turn a profit, they benefit those who pay for them and those who don't alike. Neoclassical economists -- the intellectual scions of Adam Smith -- have generally been content to treat the environment as a particularly vexing sector of the overall economy, developing a group of theories collectively known as environmental economics to sort out the thorny problems presented by goods that don't fit the market mold.
"But recently, a group of mavericks known as 'ecological economists' have begun to hammer out a new paradigm that stands economic theory on its head. Rather than the environment being a subset of the economy, they argue, the market is a subset of the global environment, and all the goods and services we trade ultimately depend on natural resources and processes."