This project was inspired by another project that I did in 2015: a Sky Scarf. The Sky Scarf is a project concept from Lea Redmond over at Leafcutter Designs: the idea is that you go outside every day for a year and see what color(s) the sky is, and knit or crochet a row in those colors. At the end, you have a scarf that is a reminder of your personal weather throughout that year. As soon as I started that project, I started thinking about the possibilities of representing other data series using some sort of color assignment that would make sense to describe the data.
In my line of work, we appreciate the value of a long dataset. It’s actually pretty difficult to commit to measure the same thing over long periods of time. One of the things that we humans have been pretty good about measuring, because it’s so important to us, is weather. But we’ve really only been doing a good job of it for less than 150 years. Fortunately, the natural world does some recording of its own: tree growth rings, glacial ice cores, and accumulated deep lake sediments preserve information that tells us about what the temperature and atmosphere were like centuries ago. Scientists have been able to put all these records together with observations from instruments to reconstruct what temperatures were like before we had the ability to measure them directly.
I decided to use data describing the average surface temperature of Earth each year and color-code it to create a scarf pattern. The color code uses shades of blue for cooler-than-normal, shades of red for warmer-than-normal, and purple for normal (because, as you will learn if you visit this blog much, I like purple!).
But temperature changes, so what is “normal”? This dataset doesn’t portray the daily or even seasonal swings in temperature that we are most familiar with in our daily lives, wherever we may live. It is an average over time (a whole year at a time) and over space (representative points around the globe, both land and sea), and that value has been fairly stable for very long periods. The period from 1600-1900 is an example of a long time when the annual global temperature varied over a small range, so I used the average from those three centuries as my reference point and called up to 0.1 degrees C above or below that “normal”. During those 300 years (the left three-quarters in the picture below), cool years (blue) were only a little cooler (0.1-0.3 degrees C below normal) and happened for a few years about once or twice per century, and warm years (red) were only a little warmer (0.1-0.3 degrees C above normal) and also happened for a few years once or twice per century. (Temperature fluctuations for centuries before 1600 were not too different from this: I just started with the year 1600 because I wanted about 400 rows for my scarf.)
Starting in the late 20th century, temperatures started to exceed this normal range that had persisted for centuries, and this is represented in the scarf by darker shades of red for every 0.1-0.3 degrees C increase. The last year in the typical historical cool range was in the early 1930s. More importantly, the last year in the typical historical normal range was in the 1970s, and since then the global average temperature has been increasing dramatically. These may seem like small temperature changes compared to the normal daily and seasonal temperature swings that we experience, but making the whole seasonal cycle just 1-2 degrees warmer overall across the globe represents a tremendous amount of extra heat that can melt polar ice, feed energy to hurricanes, and shift agricultural zones.
One of the things I learned during this project was that, even though I was already familiar with this dataset scientifically, I experienced it in a new and more personal way while creating my scarf: putting a yarn color away because I wouldn’t need it again, or getting out a new color that I hadn’t needed before, really drove home the changes as I worked through the timeline. I enjoyed sharing this more emotional connection to the science when I exhibited my scarf in November 2015 at the Coastal and Estuarine Research Federation meeting during an experimental session called “Artistic Pathways to Scientific Understanding”. We had a wonderful time learning about how other researchers integrate their scientific and artistic interests, and it was interesting to see how many different ways a scientific study could be presented without losing its core messages.
My scarf was constructed using Tunisian crochet, but the stripe pattern can be adapted to many crafts including knitting and conventional crochet. If you’d like to make a global temperature scarf yourself, I’m offering the pattern free of charge: use the download button below. I give complete directions for the Tunisian crochet version in my pattern because it’s the technique I used, and it’s less well known than other yarn crafts. I give some guidelines for how to choose yarn and stitch patterns if you want to try this with another craft technique. As with all craft patterns, please credit the author (me) when describing the pattern for your reproduced work. References to the temperature datasets that I used are included with the pattern. If you create your own representation of the data, please credit the researchers for their work in producing these complex analyses.
If you’re interested in the details behind how the data were converted to a color sequence, or if you’re interested in the color sequence for years before 1600 (the reconstruction goes all the way back to 200!), please email me.
Another feature of this scarf is that I invented a new Tunisian crochet stitch pattern for it, which gives the scarf some texture and combats the tendency of Tunisian crochet to curl. If you’re interested in a more complete description of this stitch pattern including variations, that will be the subject of a later post.
Let me know in the comments if you are interested in making a scarf or another project using this stripe pattern!