Sonification of the atmospheric carbon record over the past 800,000 years

This piece is part of a collection of sound compositions called Timescales, which sonifies datasets spanning different time scales of the atmospheric carbon record. Glaciations is a musical sonification of atmospheric carbon dioxide inferred from ice cores, from 800,000 years ago to the present. This scale encompasses the small shifts in earth’s orbit which drove the rise and fall of eight successive ice ages and alternating warm periods. The intention behind the compositional choices in this composition is to evoke a sense of vastness and wonder, and to create a sonic landscape of planetary motion and deep time., Glacial cycles are the central organizing feature of this composition. Historical time is linearly mapped to musical time: one beat in musical time represents 2,000 years. The carbon record is mapped to a pentatonic scale spanning six octaves, with 170 ppm and 420 ppm at the lower and upper limits, respectively, of CO2 measurements. 
A simple sine wave tone glides up and down to sonify CO2. Three additional longer sonic layers rise and swell with each successive interglacial warm period, all using FM synthesis. One layer is a beating sound, with three or four beats per data point. The carrier frequency of this sound is set by the first value of CO2 in the cycle, and stays constant for the duration of the cycle.  A second layer is sustained over three data points, or approximately 6,000 historical years. This sound is created with complex modulation FM synthesis. The carrier frequency is one octave below the CO2 value.  A third sound is held over the duration of the whole glacial cycle. ...,
This is a stereo wav file and can be played through any digital music player.