"Carbon dioxide in the atmosphere hasn't been this high for over 800,000 years. Now do you see why we have to stop burning fossil fuels and go to renewables?"
"It hasn't been this high for over 800,000 years? Wow! That's a pretty long time."
"You bet it is."
"And that's all because of burning fossil fuels?"
"So, carbon dioxide in the atmosphere was this high 800,000 years ago and it's happening again now?"
"How many times are you going to ask me the same question?"
"But there's only one thing I don't understand."
"Well, if the carbon dioxide was this high 800,000 years ago and it's this high now, how do you know it's because of burning fossil fuels? I mean, 800,000 years ago there was no industry, no cars, no nothing. Nobody was burning fossil fuels and the carbon dioxide
was just as high as it is now. So, how can it all be because of fossil fuels?"
"Hmm, well actually I saw this movie..."