Quit it.

This conversation needs to stop happening.

Person 1: The weather is so [insert unpredictable craziness here]
Person 2: I know! Global warming...
Person 1: Yeah...
Person 2: I'm serious! It [blanked] in [blank city]. And it's March! Can you believe that?

Person 1 is probably aware of global warming. Person 1 is just commenting on the current situation without starting a deep and depressing conversation about the state of the world. Person 2 should probably stop regurgitating what they hear on the news and presenting it as if it was their own idea. Stop being so uppity about your knowledge of global warming.