Randall Munroe, the author of the fantastic XKCD web comic, created this graphic charting Earth’s average temperature from 20,000 BCE. This visual representation is very helpful in putting our planet’s relative temperature fluctuations in the context of time, planetary events and human expansion. It is not a coincidence that the startling change in the last few hundred years comes directly after the industrial revolution and the human population boom, when carbon dioxide emissions took off.