magic-3
Explanation
This comic shows two farmers in a rural setting. One is distraught, explaining that they gave their crops water, fertilizer, and sunshine, "but nothing will grow. Nothing! Why?!" The other farmer calmly responds with two words: "Magic. Beans."
The caption at the bottom provides a fun science fact: "If Jack's beanstalk was 1000 miles tall, and about a mile thick, it'd use up all atmospheric CO2."
The joke operates on two levels. On the surface, it is a parody of agricultural frustration where the obvious (and absurd) solution is to use magic beans, referencing the fairy tale "Jack and the Beanstalk." The humor comes from the deadpan delivery of a fairy-tale solution to a real-world farming problem, as though magic beans were a legitimate and well-known agricultural technique that the struggling farmer simply overlooked.
The caption adds a layer of nerdy scientific speculation typical of SMBC. It takes the fairy-tale concept of an impossibly large beanstalk and calculates a real-world consequence: a plant that massive would consume all the CO2 in Earth's atmosphere. This functions as both an interesting thought experiment and as an implicit commentary on climate change -- suggesting that the scale of plant growth needed to solve atmospheric CO2 problems is literally the stuff of fairy tales.