DOI: 10.5061/dryad.hqbzkh1mp
title: Sonification of the atmospheric carbon record over the Holocene epoch

description: This piece is part of a collection of sound compositions called
 Timescales, which sonifies datasets spanning different time scales of the
 atmospheric carbon record. The Holocene is a geologic epoch which began
 approximately 11,700 years ago as the last glaciation ended. At the onset
 of the Holocene, atmospheric carbon dioxide concentrations were
 approximately 265 ppm, and they remained below 280 ppm until the 18th
 century and the dawn of the industrial revolution. The Holocene
 composition creates an experience of listening to the stable climate of
 the Holocene epoch, and hearing the end of the Holocene and the beginning
 of the Anthropocene. 
description: <em>Holocene</em> uses a repeated
 melody that is three measures long, each measure is a three-tone sequence
 with scale degrees: [3,1,3], [3,3,5], [3,3,8].  Each measure corresponds
 to one data point, and the pitch for all notes in the measure are
 determined by the mapped carbon midi value, so that repeated
 CO<sub>2</sub> midi values create a repeating melody. When the
 CO<sub>2</sub> value shifts up or down, the whole measure
 shifts by the same degree, preserving the interval between notes. This
 way, the melodic structure stays the same, but is translated up or down
 the scale according to the carbon record.  The CO<sub>2</sub>
 value in ppm is mapped to a pentatonic (five-note) equal-temperament scale
 spanning six octaves, from 392 Hz to 5587.65 Hz (assigned as MIDI
 values).  This pitch value determines the pitch of the first note in each
 measure. The other two pitches in the measure are determined in relation
 to the first pitch, by the aforementioned scale degrees. The mapping of historical time to musical time is
 as follows; in the first 70 beats, each beat represents 75 historical
 years. Then, this shifts to 50 historical years represented per beat for
 63 beats, and gradually reduces to 1 historical year per beat. This
 nonlinear time mapping stretches out the recent rise in
 CO<sub>2</sub> relative to the stable period.  To remind listeners that historical time ‘slows
 down’ as musical time progresses, this piece includes a digital instrument
 that plays the number of historical years represented per beat. The sound
 is a simple thud sound made with FM synthesis. For the first three
 intervals (75, 50, and 25 years per beat), the instrument sounds like
 buzzing. When the time interval reaches 10 or fewer historical years per
 beat, each individual thud sound is audible and becomes
 rhythmic. Data sonified is from the
 following two sources: Law Dome ice core (Rubino et. al., 2019) for years
 1 CE  to present, and Epica ice core (Lüthi et al., 2008) of years 8000
 BCE to  1 BCE. Both of these ice cores are from Antarctica, and are
 significantly correlated with Antarctic temperature. Rubino, Mauro; Etheridge, David; Thornton, David; Allison, Colin; Francey, Roger; Langenfelds, Ray; Steele, Paul; Trudinger, Cathy; Spencer, Darren; Curran, Mark; Van Ommen, Tas; Smith, Andrew (2019): Law Dome Ice Core 2000-Year CO2, CH4, N2O and d13C-CO2. v1. CSIRO. Data Collection. https://doi.org/10.25919/5bfe29ff807fb
description: Data is in a 24-bit, 44100Hz stereo wav file, and can be played through any digital music player.