Study: Most carbon dioxide in atmosphere in 3 million years

There is likely more carbon dioxide in the atmosphere now than ever before in the past 3 million years, when sea levels were 20 meters higher, according to a new study released this week.

Researchers at the Potsdam Institute for Climate Impact Research (PIK) used computer simulation to determine the last time the CO2 concentration in the earth’s atmosphere was as high as today, determining it was likely during the Pliocene epoch geological period 2.6-5.3 million years ago.

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The model showed that low levels of carbon dioxide may have contributed to the onset of the ice ages. However, research showed that humans continuing to burn fossil fuels at the current rates will cause global temperatures to jump.

Global mean temperatures have never exceeded industrial levels by more than 2 degrees Celsius in the last 3 million years. The study found the temperatures will exceed that limit in the next 50 years if “current climate policy inaction” continues.

"Our results imply a strong sensitivity of the Earth system to relatively small variations in atmospheric CO2," said Matteo Willeit, the lead author on the PIK study. "As fascinating as this is, it is also worrying."

Willeit told CNN that, according to the simulation, CO2 levels should not be higher than 280 parts per million (ppm) without human activity. They are currently 410 ppm and rising.

Sea levels will also rise one or two meters in the next 200 years if CO2 levels and temperatures continue to spike, Willeit. 

"It seems we're now pushing our home planet beyond any climatic conditions experienced during the entire current geological period, the Quaternary,” Willeit said in a statement. "A period that started almost 3 million years ago and saw human civilization beginning only 11,000 years ago. So, the modern climate change we see is big, really big; even by standards of Earth history."

CNN noted that previous research has suggested today’s CO2 levels are the highest since the Pliocene era, but the researchers in Potsdam say their computer simulation is the first of its kind and more sophisticated than other studies.