This cartoon is obviously about Earth Day and the health of Earth overall!
This cartoon is found humorous due to the fact that even though it gives off goofy vibes and looks like something that should be in a coloring book, it is true! On Earth day it seems like everyone turns into a hippie and wants to do everything in their power to help Mother Nature, but every other day they're their normal, all-business-no-play-selves! Another thing I found funny about this cartoon was that Earth was ON Earth! and that both sides of the cartoon a basically opposites(analyzing the Car to Bike, the Veggies to Superstore, and the Sunshine to Clouds.)
This cartoon is about the damage of nature!
The humor in this cartoon is that the man's allergies are gone because ALL the trees are cut down. While cutting down trees is usually a malicious doing, this man finds a brighter effect of the situation(even though he'll probably die due to oxygen loss because there are no plants! :P) Another humorous thing in this cartoon is just how far the stumps extend into the distance/backdrop!
These cartoons both express the fact that we should car for Earth and its well-being more often through humor and exaggeration! :D