The film manages to lampoon An Inconvenient Truth even as it is obviously on the same side as the Al Gore documentary; that pretty much describes the show in a nutshell, bringing up the issues with just enough self-deflation so that the message and not the preachiness gets through.
Political stuff's here, too, like when Lisa uses a scissor-lift to show how bad the pollution in the lake will get, a la An Inconvenient Truth, but by the end, the townsfolk are really only convinced they need a new lift.
The writers (eleven are credited) take shots at global-warming deniers as well as tweaking An Inconvenient Truth, and there�s some sobering stuff about mob mentality, but mostly the film ends up being character-driven � and nicely character-driven at that, though nothing much that die-hards haven�t seen before.
Lisa Simpson, the family's do-gooder daughter, creates her version of "An Inconvenient Truth" – it's called "An Irritable Truth" – but again, the barbs are blunted.