What is the theme in The Toxic Donut by Terry Bisson?

The main theme of "The Toxic Donut" is concern for the destruction of earth's environment. While the story takes place in the future, after humanity has devised a solution for environmental destruction, Ron, the administrative assistant, talks about humanity's past—in other words, the time in which Bisson and his readers live: "I mean it all really happened! Dead rivers, dead birds, dioxins." In Ron's time, environmentalism is a worldwide concern, so much so that there is an "International Institute of Environmental Sciences."