It is often assumed that humans began to have a significant impact on the global environment and climate at the turn of the industrial age in the 18th century, but new research shows that the older world was not quite as pristine as we might think.
Researchers analyzing Antarctic ice cores found an unexpected increase in black carbon from soot that began around the late 1200s, traceable to New Zealand, where Maori people at the time practiced burning as a land-cleaning practice.
“Compared to natural incineration in places like the Amazon or southern Africa or Australia, you would not expect Maori incineration in New Zealand to have a major impact, but it does over the Southern Ocean and Antarctic Peninsula,” said Nathan Chellman, a postdoctoral fellow at the Desert Research Institute, in a statement. “Being able to use ice core records to show effects on atmospheric chemistry that reached across the entire southern ocean, and to be able to attribute it to the Māori arrival and settlement of New Zealand 700 years ago was truly amazing.”
Chellman is part of a team that published its findings Wednesday in the journal Nature.
Black carbon is produced by burning biomass. It absorbs light and can contribute to global warming and melting of ice sheets, which can contribute to an increase in sea level. Chellman’s colleague Joe McConnell, who led the study, was surprised that humans had a significant effect on the atmosphere centuries before the modern era.
“It is clear from this study that humans have been influencing the environment across the Southern Ocean and the Antarctic Peninsula for at least the last 700 years.”
The results can help reshape how we understand the atmosphere and climate, because current climate models use information from the climate’s past to predict its future. This study shows that combustion caused by humans can have a more lasting impact on the atmosphere and perhaps the climate and on scales that are much larger than expected.
“From this study and other previous work that our team has done, such as on 2,000-year-old lead pollution in the Arctic from ancient Rome, it is clear that ice core records are very valuable for learning about past human impacts on the environment, “McConnell said. “Even the most remote parts of the Earth were not necessarily untouched in pre-industrial times.”