Decay

The same loop of four chords plays once a year and never changes. Only the quality of sound and image changes, driven by one number for the whole region each year. Bright lights and a wide halo at the start, then drained colours, thicker grain, horizontal tears and blocks of pixels, like a recording wearing out.

One value per year for the whole region, mixing three averages weighted by glacier area: how fragmented the snow is (45%), how much snow cover is lost (35%) and the gap to the reference glacier surface (20%). It is rescaled between 0 and 1 and smoothed over three years, and no trend is added. 20,150 glaciers.

Sound and image read the same yearly value, from the same list of 640 notes. The image starts to tear when the value passes 45% of its scale and to pixelate at 55%.

Plucked arpeggios over pads. As the value rises the notes lose their brightness, go out of tune by up to about half a semitone, get coarser and are dropped, and the reverb empties from 61% to 6% of the sound.