They claim that the graph in the post shows a good correlation with the succession of new kings and taxes paid on smelting silver and lead ore with the lead in the ice core, but the graph shows a weak correlation at best. However, the graph is on a log scale, so it might be hard to see.

The 1200s was the end of the Medieval Warm Period, the rise of the Bubonic Plague, also associated with a number of famines that wiped out huge portions of the European population. It was a time of great upheaval, so correlating to taxes is just a weird metric. It's interesting to note the decline in lead but I would assume this to be true of any period which led to population decline.

> the team used a laser to carve 120-micron slivers of ice

I want to know more about this process. The kerf of a laser cutter tends to be around 1000 microns, so are they just throwing away 90% of their material or is their laser something special?

Im confused what is so interesting about this. The Greenland Ice Core Project tracked ancient pollution in snow 20+ years ago, and they even discovered interesting spikes all the way back to the Roman Empire

[1] https://en.wikipedia.org/wiki/Greenland_ice_core_project

Does anyone know where to find the longest time series of this kind of data? Would be awesome to see the ebbs and flows against the long term trend of industrialization.