Carbon Dioxide Levels in the Atmosphere Hit Highest Level in 3 Million Years

According to a recent National Oceanic and Atmospheric Administration (NOAA) report, the last time carbon dioxide levels were this high was 3 million years ago “when temperature was 2°–3°C (3.6°–5.4°F) higher than during the pre-industrial era, and sea level was 15–25 meters (50–80 feet) higher than today.”

That period, the Pilocene Era, is unrecognizable from today. Earth first passed the 400 million parts per million of CO2 in the atmosphere in 2013. 

But what was once seen as an alarming threshold has now become business as usual. This year, scientists are forecasting that atmospheric concentrations of carbon dioxide will likely peak at around 417 ppm, signifying that for every 1 million molecules of gas in the atmosphere, 417 are carbon dioxide.

And with that, humanity will be charging into wholly unfamiliar territory. “For millions of years, we haven’t had an atmosphere with a chemical composition as it is right now,” said Martin Siegert, co-director of the Grantham Institute at Imperial College London, to NBC News.

In fact, just two weeks ago, on Feb. 10, NOAA’s Mauna Loa Observatory, an atmospheric baseline station in Hawaii, recorded the daily average of CO2 levels on as 416.08 parts per million, according to Common Dreams.

The concentration of carbon dioxide is closely watched as an indicator of how humans are influencing Earth’s climate. Burning fossil fuels releases carbon dioxide and other greenhouse gases that trap heat in the atmosphere. Elevated concentrations of carbon dioxide are associated with higher global temperatures, melting ice and rising seas, among other effects of climate change.

“We’ve done in a little more than 50 years what the earth naturally took 10,000 years to do,” said Siegert to NBC News.

University of Exeter geography professor Richard Betts, head of the climate impacts division at the UK’s national weather service, expects this year’s CO2 concentrations to be 10 percent higher than normal, with one or two percent of that carbon rise attributed to the Australia wildfires, as NBC News reported. The fires, which raged for nearly five months, released about 900 million tons of carbon dioxide into the atmosphere.

The Pliocene Era from 5 to 2.6 million years ago provides a window of what a world with such high carbon dioxide concentrations can look like. It was a period well before humans evolved. Temperatures at the poles then were likely about 15 degrees Fahrenheit higher than they are now, according to Siegert, who spoke to NBC News.

Image from: Kate Geraghty / The Sydney Morning Herald via Getty Images