07.24.2018
The “Temperature Circle” Deception
(For playable video, go to http://www.drroyspencer.com/2018/07/the-temperature-circle-deception/ ) I didn’t pay much attention to the ‘temperature circle’ at the time as it seemed rather gimmicky. But yesterday I was asked on social media about it, and I watched it again. The video has about 163,000 views on Twitter and 175,000 views on Youtube, and its impact on people’s perception is evidenced by some of the recent Youtube comments:
“Excellent presentation of a large mass of data. But the denialists will invent reasons to ignore it.” “We’re toast.” “This is among the scariest presentations I have ever seen. Yes, I have kids.”After thinking about the animation for a minute, it quickly became apparent why warming displayed this way looks so dramatic… and is so misleading. The best way to describe the issue is with an example. Assume all the countries in the world were 2 deg. C below normal, and then at some later time all of them warmed to 2 deg. C above normal. Here’s the way the ‘temperature circle’ plotting technique would display them (ignore the displayed year and ‘real’ data, just focus on the blue and red segments I have superimposed):

Fig. 1. The “temperature circle” animation exaggerates the perception of warming by non-linearly increasing the area of a colored annulus, even if warming progresses linearly.