High atop the Peruvian Andes, the cumulative effect of the Inca civilization’s industrial air pollution is etched into the Quelccaya Ice Cap.
Scientists have assumed as much for a while, since South America is renowned for its long metallurgic history and robust mining activity. But now, for the first time, they’ve quantified the evidence in a report for the Proceedings of the National Academy of Sciences. Their study confirms that humans began polluting the area long before the Industrial Revolution began.
It also suggests that the Anthropocene—a new geologic epoch that began with humans’ direct alteration of the planet—have have begun at different times around the world.
This research required geologists to study layers of ice, just as a rock specialist would survey stratification of sedimentary rock or as a dendrochronologist would inspect tree rings.
Here’s Lizzie Wade, writing for Science News:
For as long as people have been releasing pollution into the atmosphere, ice in Earth’s glaciers has been trapping it. The Quelccaya ice core offers a particularly vivid record of atmospheres past, thanks to the tropics’ annual pattern of wet and dry seasons. The wet season brings snow to Quelccaya, and the dry season brings dust. Once everything gets packed down into the glacier, the alternating seasons show up as stripes of “clean and dusty ice,” explains Paolo Gabrielli, an earth scientist at Ohio State University, Columbus. Anything that’s in the air at the time the snow or dust lands will eventually be trapped inside the glacier.
That means scientists can use ice cores like the one from Quelccaya to reconstruct what Gabrielli calls pollution histories. For example, trace metals released into the atmosphere by ancient Greek and Roman mining operations have been discovered in ice from Greenland. Gabrielli thought South America’s glaciers might have recorded similar human activities, especially because the continent has a long history of mining and metallurgy.
Gabrielli’s team found traces of metals, including copper and lead, in the Quelccaya ice core dating back to the pre-Columbian period. The smelting of copper had begun in South America as early as 1400 B.C.E., but the most prominent smelting industry—and likely the most polluting—was based at a massive silver mine in Potosí, Bolivia, which released previously unheard-of amounts of lead and other metals into the South American atmosphere during the colonial period. (The Spanish colonized South America in the 16 th century.) The ice core reflects this dramatic shift: between 1450 C.E. and 1900 C.E., lead levels in the Quelccaya ice core nearly doubled, and the amount of the metal antimony in the ice increased 3.5 times.
The Peruvian Anthropocene, then, seems to have begun at least 240 years before the Industrial Revolution, which some consider the start of the “Western” Anthrocopene. Analyses of glaciers elsewhere may be able to pinpoint the exact dawn of varying local Anthrocopenes, giving scientists more information about global environmental change and how different civilizations developed.
Photo Credit: Edubucher / Wikimedia Commons