Ice cores reveal that atmospheric oxygen has declined 0.7 percent over the past 800,000 years
Earth is losing its oxygen, though it’s not nearly enough to trigger any panic, a new research suggests.
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Researchers from Princeton University have analyzed the air bubbles trapped inside the ice cores from Greenland and Antarctica and found that atmospheric oxygen levels have dropped by 0.7 percent over the past 80,000 years, which is a normal pace by geological standards. However, if we look at the past 100 years, oxygen has declined relatively speedily at 0.1 percent. The pace of oxygen loss is likely accelerated by burning of fossil fuels and industrial revolution.
In the study, researchers have tried to figure out how much oxygen is drained out of Earth’s atmosphere in the past millions of years. So, they can determine the current levels of oxygen in the atmosphere and also predict the amount of oxygen available in the future. But determining the oxygen content in the atmosphere is not easy because oxygen in our planet is constantly recycled by humans, animals, plants, and even silicate rock. And it is widely accepted that weathering of silicate rocks could control long-term climate change.
In the last 800,000 years, there has been a slow decline in atmospheric oxygen: https://t.co/TawhURoZwp #PrincetonResearch pic.twitter.com/2b86LTJn6B— Princeton University (@Princeton) September 23, 2016
Weathering of rocks involves chemical reaction between atmosphere and the rocks over millions of years. As temperatures rise due to higher carbon dioxide in the atmosphere, silicate-weathering rates are hypothesized to increase and remove oxygen from the atmosphere faster.
“The oxygen record is telling us there’s also a change in the amount of carbon dioxide (that was created when oxygen was removed) entering the atmosphere and ocean,” said co-author John Higgins.
“The Earth can take care of extra carbon dioxide when it has hundreds of thousands or millions of years to get its act together. In contrast, humankind is releasing carbon dioxide today so quickly that silicate weathering can’t possibly respond fast enough.”
“The Earth has these long processes that humankind has short-circuited.”
However, researchers are unable to explain what major processes are controlling atmospheric oxygen levels. If detected, researchers could use them to better understand the fluctuations in oxygen levels or rapid acceleration compared to prehistoric times.