Climate Monday: The xkcd Earth Temperature Timeline

April 30th, 2018

It’s the final week of the semester, so it’s time for a little fun in the world of weather and climate visualizations.  One of the toughest things that Geologists have to deal with is conveying a sense of time scales.  It’s difficult for present-day humans to conceive of how long ago (or recent) the Roman Empire or Han Dynasty were, let alone 4.6 billion years of Earth history. We often use interesting comparisons, like how the time gap between Tyrannosaurus (68-66 million years ago) and humans is smaller than the gap between Tyrannosaurus and Stegosaurus (155-150 million years ago).  Sometimes we use analogies, like how an average human lifespan is 0.00000204% of all Earth’s history, which is about the same percentage of your life you just spent reading this paragraph.

With climate change, scientists often are approached with the question: “Climate has changed before, so why is this time worse?” An important is that this time it’s changing very fast, and rapid change is more problematic than gradual change. The faster the change, the harder it is for plants and animals (and humans) to adjust.  But conveying that sense of rapid change can be difficult when our time series are so long, stretching tens of thousands of years.  It rarely looks good on a single powerpoint slide or a single 8 1/2″ by 11″ piece of paper.  You either have to scrunch everything into a very condensed and crowded graph, use an inset box to zoom in on today, or use multiple slides/figures.  Or… you could use the tendency for modern webpages to scroll indefinitely to convey a sense of time.  This is the tactic of the webcomic xkcd.

No, seriously. The main reason for reading the comic is to laugh at the little bits of humor slipped in, but Randall Munroe at xkcd is diligent about scientific research.  The temperature data for the visualization are based on a combination of  HADCRUT4 (from the UK Meteorology Office), the Intergovernmental Panel on Climate Change (IPCC, funded by the UN), and peer-reviewed journal articles in the journals Nature (Shakun et al. 2012), Science (Marcott et al. 2013), and Climate of the Past (Annan and Hargreaves 2013). Those last three are all paleoclimate reconstructions.

2 Responses to “Climate Monday: The xkcd Earth Temperature Timeline”

  1. Faruk Emre Büyükkabaon 30 Apr 2018 at 1:06 pm

    Thank for the post

  2. Bill Reinthalon 01 May 2018 at 6:49 am

    That’s a great cartoon, Alex! One of the things we have to be careful about, in discussing ancient (pre-instrumental, i.e., thermometer) temperatures is that there is quite a lot of wiggle-room (error) in the data (I don’t see enough error bars in any of this). First, we have calibration uncertainties in isotopic fractionation, then we have lab/extraction procedure errors, and finally, we have unknowns regarding resetting of stable isotopes in the notoriously chemically-mobile-under-geological-conditions Ca-carbonates that are used for much of this data set (this was infamously reported on just last year, i believe in forams).

    As a recent editorial in the Wall Street Journal stated, climate scientists have been really bad salesmen. They choose/have chosen to focus on temperature-based data sets whose analysis is fraught with extreme statistical manipulation (that might not be a good word choice–I don’t mean to suggest malfeasance, just normal statistical procedure) and prone to the errors stated above, all when attempting to demonstrate relatively small temperature changes over time.

    Instead, they/we should be focusing on the visceral types of data sets you discussed in an earlier post; things the layperson can really sink their teeth into, like rapid glacial retreat, the northward march of the boreal forests, the (mostly) temperature-induced death of massive amounts of coral, the changing migration/mating habits of wild animals (etc.).

    In addition, some of the best scientists in the field have fallen into the popularity trap of “finding religion” in their quest, and have lost all their objectivity in their (unscientific) certitude in their truth, losing all credibility as scientists. This has been a popular topic amongst ethicists, as they debate whether scientists should stay in the background or become populist-activists in support of their cause.

    We have, collectively, done a really bad job as teachers to get us to this point where we have such deeply rooted skepticism. However, I think the tide is slowly changing, but perhaps not before lower Manhattan and Miami are knee-deep in the sea.

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