Until recently I had no troubles to explain what I was studying; I was just an average Maths student. I could predict the reaction of a person informed about this fact: “How can you do that? I’ve always been hopeless at Maths. And I think teaching is boring.” Things got much more complicated since I have started PhD studies at Mathematics of Planet Earth (just to clarify: not all mathematicians end up teaching in schools!). First reaction is usually the question used as a title to this article. After a brief explanation that I am learning how to use Maths in climate and weather predictions, I just get a reassuring statement: “I know that this whole climate change thing is very dangerous/rubbish”.