Because you can never have enough time series charts that show increases of CO2 and temperature over decades. By Kevin Pluck:
Differing from the variations we’ve seen before, time is on the circle, and the metrics are on the vertical. Then it rotates for dramatic effect.
See also the the two-dimensional Cartesian version from Bloomberg and the polar coordinate version by Ed Hawkins. There are also plenty more temperature charts. I think after this, we’re set for a while.