Driven by burning of fossil fuels, which consumes oxygen and produces carbon dioxide, the rate of oxygen decline from the Earth’s atmosphere has speeded up over the past 100 years, says a study.
Researchers from Princeton University compiled 30 years of data to construct the first ice core-based record of atmospheric oxygen concentrations spanning the past 800,000 years, according to the paper published in the journal Science.
The record showed that atmospheric oxygen has declined 0.7 per cent relative to current atmospheric-oxygen concentrations, a reasonable pace by geological standards, the researchers said.
During the past 100 years, however, atmospheric oxygen has declined by a comparatively speedy 0.10 per cent because of the burning of fossil fuels, which consumes oxygen and produces carbon dioxide.
“This record represents an important benchmark for the study of the history of atmospheric oxygen,” said Assistant Professor of Geosciences John Higgins.
“Understanding the history of oxygen in Earth’s atmosphere is intimately connected to understanding the evolution of complex life,” Higgins noted.
Curiously, the decline in atmospheric oxygen over the past 800,000 years was not accompanied by any significant increase in the average amount of carbon dioxide in the atmosphere, though carbon dioxide concentrations do vary over individual ice age cycles.
To explain this apparent paradox, the researchers called upon a theory for how the global carbon cycle, atmospheric carbon dioxide and the Earth’s temperature are linked on geologic timescales.