Feb. 11 (UPI) -- Scientists have discovered evidence of the Industrial Revolution's beginnings trapped in the ancient layers of a Himalayan glacier.
"The Industrial Revolution was a revolution in the use of energy," Paolo Gabrielli, research scientist at Ohio State University's Byrd Polar and Climate Research Center, said in a news release. "And so the use of coal combustion also started to cause emissions that we think were transported by winds up to the Himalayas."
The Byrd Center hosts one of the world's largest collections of ice cores. One of the cores stored at the Byrd Center was extracted from Dasuopu, a glacier on the Himalayan peak of Shishapangma, one of the 14 tallest mountains on Earth.
The layers of ice in the core were formed between 1499 and 1992. For the new study, published this week in the journal PNAS, scientists analyzed the concentration of 23 trace metals in the ice layers.
Because scientists can link layers of ice with years featuring large amounts of snowfall, volcanic eruptions or human-made disasters, researchers can precisely date each layer of ice in the core.
Their analysis of the Dasuopu core, one of the highest elevation cores ever retrieved, showed trace amounts of several toxic metals, including cadmium, chromium, nickel and zinc, which began appearing in ice layers around 1780, the beginning of the Industrial Revolution in Britain.
The trace metals trapped in the ice were produced as byproducts of industrial coal burning. It's like the metals, released into the atmosphere over London, were swept eastward by winter winds and deposited on the Himalaya's tallest peaks.
Scientists suspect some of the trace metals, including zinc, were likely produced by forest fires set to clear trees for agriculture.
"What happens is at that time, in addition to the Industrial Revolution, the human population exploded and expanded," Gabrielli said. "And so there was a greater need for agricultural fields -- and, typically, the way they got new fields was to burn forests."
Researchers found the highest levels of trace metals in glacial layers formed from 1810 to 1880, a period that featured especially wet winter weather across the Himalayas. With more ice and snow compacting to form glacial layers, more dust from the atmosphere was trapped in glacier's layers.
Though the concentrations of trace metals in the glacial layers are extremely small, they could still prove harmful to life at lower elevations.
"The levels of metals we found were higher than what would exist naturally, but were not high enough to be acutely toxic or poisonous," Gabrielli said. "However, in the future, bioaccumulation may concentrate metals from meltwater at dangerous toxic levels in the tissues of organisms that live in ecosystems below the glacier."
Researchers have previously found evidence of Roman mining operations trapped in glaciers in the Alps.