Eric Worrall’s post Making Global Warming Scarier at WattsUpWithThat included an animation of global surface temperature anomalies from Ed Hawkins of the University of Reading. [Thanks, Eric.] I’ve included the gif edition as my Animation 1, which is available from Ed Hawkins’s post Spiralling global temperatures at his blog ClimateLabBook. (The post is archived here.)
Ed Hawkins’s animation infills the data spirally as time progresses. He describes that animation:
The animated spiral presents global temperature change in a visually appealing and straightforward way. The pace of change is immediately obvious, especially over the past few decades. The relationship between current global temperatures and the internationally discussed target limits are also clear without much complex interpretation needed.
Curiously, Ed Hawkins doesn’t explain the changes in color. They appear to be time related, not temperature related.
BUT DOES THAT DATA PRESENTATION DEFEAT ITS PURPOSE?
Something caught my eye on the first viewing of the animation. See Figure 1. Did others notice the same thing?
I’ve highlighted the March 1878 anomaly in Figure 1.
Watching the animation on the first pass, I waited and waited and waited some more for those February, March and April 1878 values to be exceeded. And I was still waiting more than 100 years later on the animation. See Figure 2.
As shown in Figure 3, it wasn’t until 1990 that the March and April 1878 values were surpassed.
Did Ed Hawkins really want to draw everyone’s attention to that curiosity? See the summation in Figure 4.
Figure 4 (Click to enlarge.)
It’s simply an easy-to-overlook (statistically insignificant) blip in a time-series graph. See Figure 5.
Maybe the long-term trend of the time-series graph (about +0.05 deg C/decade or about +0.5 deg C/century) was too low for Ed Hawkins?
It shows up as a multi-year blip when the data are smoothed with a 61-month running-mean filter…basically the same as the 5-year running mean filter used by GISS and Berkeley Earth. See Figure 6.
Now Ed Hawkins has introduced that 1878 blip to people who may normally have not noticed it before…especially when GISS and NOAA conveniently begin their data two years after it in 1880.
Will most people see those February, March and April temperature anomalies from 1878 sitting there unsurpassed for over 100 years, my Figures 1 and 2 ?
What will they think when they see it?
Will it help them to continue to dismiss global warming as a problem?
Will it make skeptics out of others, when they see it?
Or will Ed Hawkins’s graph have the impact he desires?