The authors of the new work analyzed ice core samples from James Ross Island in Antarctica, and found a serious excess in the level of black carbon there: it began 700 years ago.
The pollutant – black carbon or soot – appears in the atmosphere, for example from forest fires or fossil fuel combustion, and is composed of light-absorbing particles.
The soot may have appeared in the area after the Maori people in New Zealand began burning land, the researchers said. This farming practice has affected the atmosphere in much of the Southern Hemisphere, and has also become a major source of environmental emissions in the region over the past 2,000 years.
To determine the source of the contamination, the authors analyzed six ice cores they collected from James Ross Island and mainland Antarctica. As a result, they found that the James Ross Island ice core increased dramatically in black carbon around 1300, and that levels tripled over the next 700 years and peaked in the 16th and 17th centuries.
Then the authors built a model of atmospheric transport and deposition of soot in the southern hemisphere and found that the most likely sources of emissions were Patagonia, Tasmania and New Zealand.
The frequency of fires began to increase in about 1300, at the same time the Maori colonized the territories and began to burn the forests of New Zealand.