(RNN) - Earth's atmosphere is losing oxygen, and it's gotten worse over the past 100 years.
There's no need to panic but the study does show cause for concern.
Princeton University scientists found the concentration of oxygen in the atmosphere declined 0.7 percent in the past 800,000, which is not a big deal. But more worryingly, it fell at a speedy 0.1 percent in the last century.
The world's ecosystem is in no immediate danger from this particular problem, the scientists said. But they did say it's probably caused by increased carbon dioxide from burning massive quantities of fossil fuels over the past 100 years.
The team tested tiny bubbles of air trapped for thousands of years in ice cores taken from Greenland and Antarctica to reach their conclusion and found a steady drop in oxygen.
"We did this analysis more out of interest than any expectation," researcher Daniel Stolper of Princeton University told Gizmodo. "We didn't know whether oxygen would be going up, down or flat. It turns out there is a very clear trend."
They aren't sure what caused the long-term decline, though carbon dioxide concentrations do fluctuate over vast swaths of geologic time.
Earth has a way to regulate the amount of carbon dioxide, but the process takes hundreds of thousands or millions of years, according to their published study in the journal Science.
A slow chemical process between silicate rocks and the air removes carbon dioxide from the atmosphere by trapping it in solid form as calcium carbonate.
That process is far too slow to keep up with skyrocketing CO2 emissions, a co-author of the study said.
"Humankind is releasing carbon dioxide today so quickly that silicate weathering can't possibly respond fast enough," said John Higgins, an assistant professor of geosciences at Princeton. "The Earth has these long processes that humankind has short-circuited."