The Roman Empire had official historians—but can we trust their accounts, or were they burnishing history to please the emperors? A closer look at Roman silver has helped find the answer.

And surprisingly, this closer look came in Greenland. The ice there has recorded 130,000 years of history, as the atmospheric particles of each year are deposited in a layer of ice, one atop the other.

By drilling ice cores, then analyzing these layers with microscopes and spectrometers, we can read them like tree rings to build a detailed picture of the atmosphere over time.

This has helped today’s scientists study ancient climate, volcanic eruptions, and the success or failure of agriculture as told by pollen grains. It’s also revealed a lot about Rome.

The coin of the realm was the denarius, made of silver smelted from galena, a lead ore.

When the Roman economy was booming, smelters across the Empire pumped out silver, and spewed lead fumes into the atmosphere—which wafted across Europe to Greenland, where they settled on the ice and were preserved.

When the economy slumped, the smelters went quiet, and lead-laden emissions declined.

Researchers have now analyzed the lead levels, and they closely correspond to Rome’s official history—falling during wars and in times of plague, rising after wars and in times of peace.

Rome’s imperial storytellers largely agree with the ice cores, an admirable truth in journalism that spanned 600 years.