Meerpott is a playful and unique compound word created by the artists, combining "Meer" (sea/ocean) and "Pott" (a colloquial term for the Ruhr area in Germany, but also meaning "pot").
In the song, the 257ers, who are from the Ruhrpott, declare, "Wir machen den Ruhrpott zum Meerpott" (We're turning the Ruhrpott into the Meerpott). This imaginative word perfectly encapsulates their absurd and humorous vision of transforming their landlocked industrial home into a coastal paradise, complete with beaches and surfing. It's memorable because it's a neologism that captures the song's central, fantastical theme.
"Ich will Meer" is satire. 257ers play a narrator who claims to love the sea so much that he's actually rooting for climate change, since rising sea levels mean more beach for everyone.
The joke runs through the whole song: he "rides cargo bikes on purpose," slaps "Fuck you Greta" stickers on his oil rig, wants a "climate upgrade," and can't wait for the polar caps to melt so he can party in the sun. He mocks people who worry about the consequences, brushing off floods, drought, and lost habitats as someone else's problem.
It's a jab at climate change deniers and anyone who treats a global crisis as a personal inconvenience to laugh off, wrapped in absurd, over-the-top bragging about wanting nothing but "meer" (more, and sea).