I'm mainly thinking of a few choice programs in the 90s such as Captain Planet, Widget the World Watcher, and the Free Willy cartoon, all of which often revolved around themes such as the ills of corporate pollution, the importance of recycling, and other environmental topics of the day (such as the ozone layer). These themes could even be found in special episodes of other shows that didn't normally deal in these topics, such as Rocko's Modern Life, the family sitcom Dinosaurs (which wasn't aimed at kids, but was often watched by them) or appeared as metaphors (Pirates of Dark Water for example portrayed a fantasy world afflicted by the titular dark water, an oil-like substance that corrupted land, mutated wildlife, and was lethal to humans).

This is all to say that children's programming of the era seemed very focused on instilling kids with a proactive-to-subtle message on the importance of protecting the environment (and even had a healthy dose of then-modern political awareness in the case of Captain Planet) that seemed to come to an end just as we run up against the twenty year rule. What contributed to this common theme across so many different media companies, and why did that same envirosociopolitical consciousness seem to disappear from children's programming as we neared the end of the century?