The Last Time Carbon Dioxide Levels Were This High, Humans Hadn’t Evolved

The Last Time Carbon Dioxide Levels Were This High, Humans Didn't Exist

This month carbon dioxide concentrations in the atmosphere surpassed 400 parts per million globally for the first time since the National Oceanic and Atmospheric Administration (NOAA) started tracking it.

Concentrations are measured at 40 sites globally including two Arctic sites and a site in Hawaii.

“It was only a matter of time that we would average 400 parts per million globally,” Pieter Tans of NOAA’s Global Greenhouse Gas Reference Network said in a news release, reported by IFL Science. “This marks the fact that humans burning fossil fuels have caused global carbon dioxide concentrations to rise more than 120 parts per million since pre-industrial times.” Half of that rise came about after 1980.

The last time carbon dioxide levels were this high, humans had not even evolved yet, so we’re not quite sure what this means for the human race. But it’s no good.

According to IFL Science:

[G]lobal concentrations are expected to stay above 400 ppm through May: While decaying plant matter and soil microbes give off CO2 all year long, a dormant period in plant growth means respiration of CO2 is heightened during these months. Levels drop as plants start to bloom late in the spring and summertime, since CO2 is used during photosynthesis.

Carbon dioxide is emitted mostly by humans, who account for 82 percent of greenhouse gas emissions. Though the gas is naturally present on Earth, human activities are adding carbon to the atmosphere as a result of the combustion of fossil fuels for electricity, transportation, and industrial processes. Prior to the industrial revolution, the carbon cycle was balanced, that means that it was constantly being emitted and absorbed by the atmosphere, but fossil fuel combustion has led to more carbon that can be safely absorbed. That’s why levels are on the rise. It’s a process that’s difficult to turn around, but it can be done.

“Elimination of about 80 percent of fossil fuel emissions would essentially stop the rise in carbon dioxide in the atmosphere,” says James Butler of NOAA’s Global Monitoring Division. “But concentrations of carbon dioxide would not start decreasing until even further reductions are made and then it would only do so slowly.”

If carbon dioxide levels continue to rise the atmosphere will continue to warm because greenhouse gas emissions block heat in the atmosphere from escaping. Just to give you an idea, humans have increased carbon dioxide concentrations by one-third since the industrial revolution. That’s a huge number. If you’re wondering the easiest way that we as a society can reduce the greenhouse gas emissions that are warming our atmosphere, stop the combustion of fossil fuels like crude, coal, and natural gas. Additionally, stop eating the animal products which come from livestock that produce methane. It’s no easy feat, but when you consider the alternative, greenhouse gas emissions must be reduced and rapidly.

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Image of greenhouse gas emissions from Shuttershock