Silver Lining
Explanation
The Joke
Two characters are lying on a hillside looking up at the clouds. One says the familiar optimistic saying, "They say every cloud has a silver lining." The other responds, "That's because of all the mercury pollution." When the first character says "Your generation will probably need to do something," they think this is a metaphorical call to action. But then the conversation takes a dark turn: "I thought that was a metaphor." "It used to be. Environmental damage has ruined a lot of our idioms."
The final panel delivers another example: the saying "There are plenty of fish in the sea" has also been ruined -- presumably because overfishing and ocean pollution have made that statement literally untrue.
The Humor
The comic takes familiar optimistic idioms and makes them literal, then shows how environmental destruction has ruined them. "Every cloud has a silver lining" becomes a grim statement about mercury contamination in the atmosphere. "There are plenty of fish in the sea" becomes a painful reminder of overfishing and collapsing fish populations. The humor works through the unexpected intersection of language and ecology: environmental damage is so pervasive that it has not only destroyed ecosystems but also invalidated our metaphors for hope. There is a particularly clever irony in the fact that the very phrases we use to stay optimistic about the future have been undermined by our failure to protect it.
References
Mercury pollution is a real environmental concern. Mercury enters the atmosphere through coal burning, industrial processes, and mining, and eventually deposits in water and soil. The comic also references overfishing, with many major fish stocks having declined dramatically. The UN FAO reports that roughly one-third of global fish stocks are overfished. The idiom "every cloud has a silver lining" dates back to John Milton's "Comus" (1634), and "plenty of fish in the sea" has been used as a consolation phrase for centuries.