Ever since the "hockey-stick graph," climate science and graphic design have been intimately associated with one another. It's a tough science to communicate, since it plays out over the course of generations, taking potentially hundreds or even thousands of years to complete a global climactic shift. How do you effectively communicate a subtle but potentially catastrophic shift for our planet? Do you use a log scale, or a linear one? Do you use annual averages, or high temperature records, or what?
A new visualization from University of Reading climate scientist Ed Hawkins has a novel approach: putting monthly average temperatures on a circular graph and animating the outward spiral toward certain amounts of deviation from that month's global average in the 1850-1900 range.
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The graph chose 1850 as the earliest year in the animation because that's when we begin to see the temperature data we need to make the comparison. The red lines represent 1.5 and 2.0 degrees Celsius deviation from the 1850-1900 global temperature average for that month. Those thresholds were chosen by the international community, not Hawkins — at the end of the day they're just nice, round numbers we can use for comparison, but they are useful because they tend to be associated with major shifts in global climactic behavior. The goal, seemingly impossible at this point, is to stop the outward spiral before it hits the 1.5 degree mark, but the 2.0 mark is clearly the more achievable goal at this point.
A few things are immediately obvious, upon glancing at this infographic. The first is that an astonishing amount of the progress we've made toward the internationally-discussed thresholds of deviation from past averages has come in the past few decades. The rate of outward movement toward the first threshold temperature is somehow more effective than an upward-sloping graph.
If you look more closely, you'll see some interesting points in climactic history. There's the various El Nino events that increase temperatures for a short time, the most memorable of which came in 1877. In the 1880s to the 1910s we observe a bit of cooling, which the graphic's creator claims was partially due to volcanic eruptions changing the permeability of the atmosphere to sunlight. There's a marked recovery in the 1910-1940 range, as the effects of those eruptions cleared, and the sun happened to naturally increase its energy output. At this point, the greenhouse effect caused by the industrial revolution had yet to build up to a harmful extent.
The controversial "hockey stick" visualization of uptick in global temperature, created by Mann, Bradley & Hughes in 1999.


El Nino is also somewhat responsible for the big jumps since 2000, naturally pushing up temperatures in 1998 and 2016. Still, it can't account for anywhere near the entirety of the discrepancy.
One thing pointed out by Hawkins himself is that while this trend might seem to be taking on a momentum all its own, the reality is it is still moving outward in response to human behavior, so in principle it should still be possible to reverse that trend by changing those behaviors. Many climate scientists have spoken of a "tipping point" past which climate change could become temporarily self-sustaining — but despite the visuals on this graph, there are still optimists among the best educated on this topic.
We'll see how long that lasts.