(CN) – Long before humans explored the world's highest peaks of the Himalayas, new research released Monday reveals our pollution got there first.
The study, published in the Proceedings of the National Academy of Sciences, posits that pollution from coal-burning Europeans during the early Industrial Revolution in the late 18th century was found in the Dasuopu glacier, about 6,400 miles from London.
"The Industrial Revolution was a revolution in the use of energy," said Paolo Gabrielli, lead author and research scientist at The Ohio State University Byrd Polar and Climate Research Center. "And so the use of coal combustion also started to cause emissions that we think were transported by winds up to the Himalayas."
The researchers were part of a larger team that traveled to the glacier, located about 23,600 above sea level, to gather data about environmental changes that affected Dasuopu over time. The glacier sits atop Shishapangma, one of the 14 tallest mountains in the world.
Drilling ice cores from the glacier, the team was able to piece together a climate record. The scientists said the ice cores "operate as sort of timeline," able to show exactly when new layers of ice formed.
Gabrielli and the rest of the team analyzed the ice core and discovered the presence of toxic metals like nickel and cadmium in the ice dating back to around 1780, the start of the Industrial Revolution. The metals are byproducts of burning coal, largely used by emerging factories and industries at that time.
The scientists believe the pollutants were likely carried by winter winds that travel from west to east. They also said some of the metals, including zinc, could have originated from large forest fires used to clear out land for farms.
"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."
Gabrielli noted that the contamination in the glacier arrived before humans did. Shishapangma, at 26,335 feet, wasn't climbed until 1964. He said the metals found in the glacier were not at a level considered dangerous but cautioned that continual build-up of such metals could change that.
"The levels of metals we found were higher than what would exist naturally, but were not high enough to be acutely toxic or poisonous," he 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."
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