The average temperature on earth has always had its ups and downs. Changes in the tilt of the earth’s axis, volcanic activity, changes in solar activity and more have all helped make the planet warmer and colder over time. During the Paleocene Earth was so warm that crocodiles swam above the Arctic Circle. Just 20,000 years ago, it was so cold that thick glaciers covered Canada and about half of the United States.
Usually scientists share that information about the Earth’s changing temperature in graphs that look like this:
If that’s as hard for you to relate to as it is for me, then you’ll probably like Randall Munroe’s illustration more. His timeline puts these temperature changes in perspective. To get you started, all the temperatures in the graph, whether colder or warmer are compared to the average temperature between 1961 and 1990. One degree Celsius is equal to almost 1.8 degrees Farenheit.