What? Littering is just slovenly and piggish, unless you're tossing something biodegradable out like a apple core. This is sort of a non-sequiter though. Littering to global warming. What do they have to do with each other? Is this woman just clueless as she doesn't know where her kid gets it?
Littering is certainly rude. It’s ugly and destroys property value.
But as far as not being biodegradable- neither is a rock, generally. As long as animals can’t choke on it or become tangled, there is no great harm caused by non-biodegrading trash.