Quirks & Quarks

700 years ago Maori land clearing left a sooty signature in Antarctica, researchers find

Ice core samples suggest that human influence on the atmosphere goes back centuries before the industrial revolution.

Ice core samples suggest human influence on atmosphere goes back centuries before the industrial revolution

Soot from this ice core sample taken from James Ross Island in the northern Antarctic Peninsula, revealed the surprising impacts of Māori burning in New Zealand starting in the late 13th century. Robert Mulvaney, Ph.D., from the British Antarctic Survey, pictured here led collection of the core (Jack Triest)

Ice core samples from Antarctica have revealed sooty deposits dating back 700 years, which researchers have traced to forest burning by the first human settlers on New Zealand. The work suggests human activity has had an influence on our atmosphere for centuries before the industrial revolution. 

Archeological evidence suggests that ancestors of the Maori people first arrived and settled New Zealand from Polynesia, about 1250 to 1300. A recent ice core study led by Joe McConnell and his colleagues has added information that helps refine the date of arrival closer to 1300. McConnell is a professor of hydrology at the Desert Research Institute at the University of Nevada.

McConnell and colleagues from the British Antarctic Survey analyzed samples taken from glaciers on James Ross Island off the northeastern tip of the Antarctic Peninsula.

Ice core mystery

The ice core samples preserve annual records of snowfall and any particulates that fall with the snow. The team was initially surprised to find soot in layers dating to 700 years ago. Soot, or black carbon, usually comes from forest fires, or the burning of fossil fuels, which clearly didn't have a local origin in treeless Antarctica.

Measuring the chemistry in a sample of an ice core in a specific analytical system (Joe McConnell)

The soot had clearly come from elsewhere, and their research suggested that New Zealand was a likely fit. Charcoal deposits in New Zealand sediment indicated a dramatic increase in fire around the year 1300, which coincided with estimates of the date of arrival of the ancestors of the Maori. The charcoal and the soot were likely from the use of fire to clear land by the new settlers. 

Winds carried soot a long way

New Zealand is 7,200 kilometres from James Ross Island, which meant the soot travelled an enormous distance. However the southern hemisphere's powerful prevailing winds would have served to carry the soot to Antarctica. 

In addition to the ice core sample from James Ross Island, four ice cores were taken from continental Antarctica, including two as part of the Norwegian-American International Polar Year Antarctic Scientific Traverse (Stein Tronstad)

Apart from helping refine the arrival date of the Maori in New Zealand, the Antarctic ice cores revealed a previously little-known history of human influence on the Earth's atmosphere.

Produced and written by Mark Crawley.


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