Al Gore would be proud: so far, Season 21 is the most environmentally-friendly season of The Simpsons yet. What makes this season so green? Each episode is made from a recycled plotline from an earlier episode:
Homer the Whopper: Radioactive Man but with Homer instead of Milhouse
Bart Gets A ‘Z’: Sweet Seymour Skinner’s Baadasssss Song but with Mrs. Krabappel instead of Principal Skinner
The Great Wife Hope: The Homer They Fall but with Marge instead of Homer
Congratulations on reducing your carbon footprint, Simpsons writers! 
[Simpsons Archive]
In a top ten list of the top ten environmental films (#9: FernGully), Ken Eisner rounds off his appraisal of Al Gore’s An Inconvenient Truth with a solicitation to “look for some of these themes to emerge in The Simpsons Movie, from Al’s pal Matt Groening.” [