Guest essay by Eric Worrall
Back in May, Climate scientist Ed Hawkins published a scary spiral graph which appeared to show global warming leaping out at you. As a homage to Hawkins’ effort, I created a similar graph, covering the last 10,000 years, rather than just covering temperatures since 1850. The effect of the longer timescale is quite different to the Hawkins original.
The spiral graph is obviously more art than science, but it presents some interesting features. The radius of the circle is related to the temperature anomaly – warmer temperatures have a larger radius. The factors are obviously chosen for artistic impact – just as Hawkins’ factors were.
On a 10,000 year timescale the spiral graph does emphasise how cold modern temperatures are, compared to the rest of the Holocene – at least with regard to temperatures on the Greenland Ice Sheet.
Unfortunately the graph ends well before 2016 – the most recent row of the data series on which the graph is based corresponds to the early 1900s. Nevertheless, it would take a really radical warming event to match some of the natural temperature excursions which appear on the graph.
I considered consulting with Dr. Mann, to request his assistance with splicing unrelated temperature series, to plot more recent values, but Dr. Mann is probably busy with all his lawsuits.
The source code for the software which produced the graph is available here. Feel free to play with it and produce your own variations. A possible improvement might be to name the various temperature excursions (warm and cold periods). Let me know if you find any serious mistakes. The code was developed using Apple Xcode.