Breathing

Each glacier of western North America is a light that breathes: it swells and fades at its own pace, never in step with the others. The more of its reference surface is still detected as glacier, the stronger its light. When a glacier drops by more than 20 points in one year (from 80% to 60% of its reference surface, for example), a white flash goes off on it, at a moment of its own. The year is written in the image.

For each glacier and each year, the part of its reference surface still detected as glacier, from 0% to 100%, measured on satellite images. Missing years are filled by a straight line between the neighbouring years. The map is projected and turned so that the north-west is on the left.

Each glacier is a point of light on a black canvas, blurred to make a halo, that swells and fades every one to three seconds. Image and sound come from the same list of events, so a flash and its note happen at the same instant.

Notes fall at random, more often when many glaciers are still lit. Each note is a glacier, higher when the glacier is healthier, and its position on the map sets where you hear it from left to right. Each flash adds a brighter, higher note, and a long reverb blends everything.