Rings

The rings of a tree trunk, made of glaciers. Each ring is a year, with 1984 at the centre and 2025 at the edge, and each slice of the disc is a glacier, about 22,000 sorted from south to north and then west to east. Colour is the share of the glacier covered by snow that year, from cyan (a lot) to red (almost none), and grey-blue where it was not observed.

For each glacier and each year, the share of its surface covered by snow, from 0% to 100%. Missing years are left empty and not filled.

Each pixel is read straight from the table: its distance to the centre gives the year and its angle gives the glacier. Nothing is smoothed, so every coloured cell is a real measurement.