Miskatonic University Press


climate.change talks

I was at Libraries and Archives in the Anthropocene: A Colloquium, 2017 on 13–14 May. I’ll be posting more about it soon, but here is the audio and text of the five-minute talk I gave: “GHG.EARTH.” I was delighted to be there. My thanks to Rory Litwin, Madeleine Charney and Casey Davis Kaufman for organizing it.


I have five minutes.

Before I start: this talk is CC-BY; it is licensed under a Creative Commons Attribution 4.0 International License.

Near NYU.
Near NYU.

5: Introduction

Minute five. Introduction.

Hello. I’m William Denton, a librarian at York University in Toronto, Canada. I’m going to talk about GHG.EARTH. GHG is for “greenhouse gases” and EARTH is for “earth.”

This is a web site. But do not look at it right now! Please get ready to look at it. Open a tab in a browser (Chrome or Firefox, any device), type in GHG.EARTH, but don’t hit Enter yet. Do not hit Enter! Wait until minute four.

Some background. I’ve been working on sonifications, turning data into sound. Climate change research produces a lot of data, especially time series, and it’s interesting and useful to turn that into sound or music. Sonifying atmospheric carbon dioxide you hear the yearly fluctuations as the northern hemisphere takes in carbon in the summer and releases it in the winter. And you hear the rise, year after year, of the greenhouse gases we are adding to the atmosphere. Sonifying long time series of climate data makes very clear the sudden changes we have caused since industrialization.

GHG.EARTH, however, just does one thing. It plays yesterday. It turns yesterday’s CO2 measurement into sound.

4: Performance

Minute four. Now we’re going to perform it.

Get ready: when I say “now,” hit Enter. You’ll see a number and you’ll hear a sound. At the end of the minute I’ll count down to five, then please close the tab. Everybody ready? Now!

[At the end of the minute, count down: five, four, three, two, one, STOP.]

Thank you for the performance.

3: The Number

Minute three. The number.

The number is yesterday’s CO2 reading, in parts per million (ppm), taken at the National Oceanic and Atmospheric Administration observatory in Mauna Loa, Hawaii. This is where the famous Keeling Curve is from. A script scrapes the data every day from its web site. Follow the details link for the code and everything else.

The usual estimate is that before the Industrial Revolution CO2 was at 280 ppm. We’re over 400 now, and it won’t go back under in our lifetimes.

IPCC models make predictions about how much CO2 will be in the air depending on different actions we take. In the best-case scenario emissions peak very soon, then decline, and by about 2070 we’re actually removing CO2 from the air. In that case in 2100 we’ll be at about 420 ppm.

In the worst-case scenario, by 2100 we’re at 936 ppm, which would mean unprecedented global catastrophe.

So far we have consistently been beyond the worst-case scenario. There is no indication that will change.

2: The Sound

Minute two. The sound.

This is a composition. The score is: “Play the tone (Hz) equal to the atmospheric CO2 concentration (ppm).” There is no end specified. There is no arrangement or instrument specified. Anyone can play this for as long as they want, however they want, wherever they want. Like we just did.

A piano has just over seven octaves, with pitches from 27.5 Hz to almost 4200 Hz. All current and historical CO2 readings map to a pitch somewhere in that range. 440 ppm, for example, is A above middle C, “concert pitch”—what an orchestra plays when it tunes up.

280, the pre-industrial number, is a C#, the black key above middle C in the fourth octave of the piano.

410, where we are now, is a little higher, just below G#.

420, best case, is just over G#, still in the same octave.

936 is an octave up, into the fifth octave, at A#5. That is incredibly, dangerously high.

It’s hard to hear the day-to-day changes in GHG.EARTH because it’s microtonal. I’ve never been able to remember yesterday well enough to distinguish it from today, but I keep trying.

1: One Octave to Live In

Minute one. One octave to live in.

Doubling the frequency makes a pitch go up one octave. 440 is A in the fourth octave and 880 is A in the fifth octave. The musical scale is a geometric progression. It’s exponential.

An arithmetic progression is linear: it changes by the same amount every time. Annual CO2 concentration is almost arithmetic. It actually grows slightly differently every year, 2 or 3 ppm, but close enough.

The two numbers, the musical and the atmospheric, are literally working on different scales.

That means we only have one octave to live in. That fourth octave on the piano, from middle C up to B, that’s where we have to stay.

Pre-industrial we were at C#. Now we’re getting close to G#. All of human existence has been in just a few piano keys above middle C. We need to stay there. We definitely do not want to get into the next octave, which starts at about 525.

But that’s long term. GHG.EARTH is there to tell us what CO2 concentration sounds like right now. Play it in the background, quietly, and after a while it will fade out of your attention. You’ll start thinking about other things, but then it will come back—sharply. You’ll remember what it means, and you’ll remember the situation we are in.

Thank you.