Traces in the ice

Because of lead’s connection to precious metals like silver and the fact that natural lead levels in the environment are very low, scientists have found that lead deposits in layers of Arctic ice are a sensitive indicator of overall economic activity throughout history.

The Scientists used thirteen Arctic ice cores from Greenland and the Russian Arctic to measure, date, and analyze lead emissions captured in the ice from 500 to 2010 CE, a period of time that extended from the Middle Ages through the Modern Period to the present.

“We have extended our earlier record through the Middle Ages and Modern Period to the present,” explained Joe McConnell, Ph.D., lead author on the study and Director of DRI’s Ultra-Trace Ice Core Chemistry Laboratory in Reno, Nevada.“ Using an array of thirteen ice cores instead of just one, this new study shows that prior to the Industrial Revolution, lead pollution was pervasive and surprisingly similar across a large swath of the Arctic and undoubtedly the result of European emissions.”

The research team found that increases in lead concentration in the ice cores track closely with periods of expansion in Europe, the advent of new technologies, and economic prosperity. Decreases in lead, on the other hand, paralleled climate disruptions, wars, plagues, and famines.

“Sustained increases in lead pollution during the Early and High Middle Ages (about 800 to 1300 CE), for example, indicate widespread economic growth, particularly in central Europe as new mining areas were discovered in places like the German Harz and Erzgebirge Mountains, “McConnell noted. “Lead pollution in the ice core records declined during the Late Middle Ages and early Modern Period (about 1300 to 1680 Ce) when plague devastated those regions, however, indicating that economic activity stalled.”

Even with ups and downs over time due to events such as plagues, the study shows that increases in lead pollution in the Arctic during the past 1500 years have been exponential.