In short, they have reconstructed year-by-year economic data documenting the rise and fall of the Roman Republic and Empire. The first news of the record was published Monday afternoon in Proceedings of the National Academy of Sciences.

Why does the amount of lead in the atmosphere tell us something about the Roman economy? “It’s a proxy for coin production. That’s the biggest thing,” said Seth Bernard, a professor of ancient history at the University of Toronto. When the Roman government needed to pay for something, it ordered the creation of new silver coins. These coins were produced, in part, in mines on the Iberian peninsula. But these mines didn’t excavate pure silver: Instead, they unearthed an ore of silver, lead, and copper that had to be smelted into silver. This process filled the air with lead pollution.

Once in the air, these lead emissions did not stay in one place. Instead, it wafted with the winds, eventually blowing into squalls and storms over Greenland. When these storms deposited lead-tainted snow or sleet over the Arctic island, the precipitation fused with the ice sheet and became its newest layer. Century upon century of snow and ice fell on the ice sheet, burying but never disturbing that old layer of ice—until 1999, when climate scientists began coring the ice sheet at the NGRIP site. Four-inch tubes, documenting those ancient layers of snow and sleet, were hauled to the surfaces and pristinely preserved.

“There isn’t anything close to this detailed” documenting the Roman economy, said Joe McConnell, a professor of hydrology at the Desert Research Institute and one of the authors of the paper. “Our record is dramatically different both in its temporal resolution and in its dating precision.”

“The paper speaks for itself,” said Seth Bernard, who had early access to its findings but did not work on the research. “It feels sort of like we’ve discovered the Americas. There was another continent over there, that was always there, that we can see now. And I think that continent is scientific approaches.”

The new paper contains findings that Roman historians can already apply to their work. It finds that Rome’s economy waxed and waned, following well-documented events in its history, including wars and plagues. In 218 B.C., for instance, when Rome fought with Carthage in the Second Punic War, lead pollution appears to fall—and then it rises, abruptly, as Roman soldiers seized Carthaginian mines in southern Spain and put them to use. It also detects nonviolent events: When Rome debased its currency, reducing the amount of silver in each denarius coin in 64 A.d., lead pollution in the air fell.

And it provides crucial economic context for some of the most pivotal events in Roman history, including the death of Julius Caesar (and the birth of Jesus of Nazareth). The Crisis of the Roman Republic—the series of civil wars and political strife, spanning 134 B.C. to 27 B.C., that brought the Roman Republic to an end— were associated with a broad period of economic stagnation and disintegration, the study finds. And the early Roman Empire—especially the Pax Romana, the 206 years of mostly uninterrupted peace throughout the Mediterranean—were accompanied by an economic boom. When compared with other studies, research suggests that Western Europe may have seen higher lead emissions during the Pax Romana than at any time prior to the Industrial Revolution, nearly 1,800 years later.