Deep time
Forty-two datasets read as strata. The deepest coverage sits at the bottom.
Most of the CleanZones grid is a photograph. A layer arrives as one release (one epoch, one composite, one bake) and that single state is what a cell reads today. A few layers carry a real record: cyclone tracks back to 1975, the tsunami and storm-event catalogue back to 1950, ten years of ADS-B. This chart puts the two side by side so nobody has to guess which kind they are holding.
Reading it
Traced to the live dataset manifest, the release we ingested and the years that release covers. A layer that is one dated edition draws as a single mark on its year. A hollow mark means the manifest records the harvest date and the upstream release names no year, so the mark shows when we pulled it.
Each of these names a dataset that is identified, licensed for this use, and deeper than the slice sitting in the database. SPEIbase publishes 122 years of drought and one month of it is ingested. GHSL publishes seven population epochs and one is ingested. The distance between the tones is back-fill that exists and has not been run.
Some layers have no depth to draw. Soil, distance to coast, fault geometry and aquifer state each describe one condition, and the seismic hazard model rests on a record measured in geological time. Those sit at the bottom of the chart with the year axis left empty, because a bar across it would invent a series that was never there.
The chart opens on the deep end. Drag or scroll it rightwards to reach the present. Hover or tab a row for its sources.
Fine print
Four holes in the record. Here they are, in the open.
Light pollution runs on a VIIRS DNB annual composite. The manifest records the harvest and the licence, and it never records which annual composite was taken. Until that is written down the mark shows the harvest date.
The climate layer's vintage reads 33yr window / 2024 spectral. The length is recorded and the first and last year are not, so that bar is drawn hatched and anchored on the only year the manifest names.
Air quality, pollen, forest cover, lightning, microplastics and reservoirs all carry a vintage string with no release year in it. Each draws as a hollow mark on its harvest date, which is a weaker claim than a dated release and is shown as one.
It says the years exist under a licence we can use. It says nothing about the harvest, the storage or the reprocessing needed to put them on the grid, and none of that is scheduled on this page.
Every figure above comes from the live dataset manifest that ships with the grid, version 2026.08. If a layer's coverage changes, the manifest changes first and this page follows it. The Bulk API serves the same lineage per metric, and the metric reference explains what each layer measures.