High CO2 atmosphere a first in history of humankind

A new study has proven that Earth’s carbon dioxide atmospheric concentrations only exceeded 320 parts per million in 1965, a high point never before reached since humans first walked the Earth.

A high-carbon dioxide atmosphere only became the norm on Earth in the last 60 years, according to a new study published in Nature Communications.

According to the study, carbon dioxide concentrations averaged 230 parts per million during the entire 2.5 million years of the Pleistocene era. Today’s levels are now more than 410 parts per million. The shift came in 1965, when carbon dioxide atmospheric concentrations exceeded 320 parts per million.

“According to this research, from the first Homo erectus, which is currently dated to 2.1-1.8 million years ago, until 1965, we have lived in a low-carbon-dioxide environment – concentrations were less than 320 parts per million,” said Dr. Yige Zhang, a co-author of the research study and an assistant professor at Texas A&M University.

“So, this current high-carbon-dioxide environment is not only an experiment for the climate and the environment – it’s also an experiment for us, for ourselves.”

The scientists analyzed soil carbonates from the Loess Plateau in central China to quantify ancient atmospheric carbon dioxide levels going as far back as 2.5 million years ago. They then used the data to construct a carbon dioxide history of the Pleistocene. Their results are in line with snapshots of early-Pleistocene carbon dioxide retrieved from old, blue ice in the Antarctic, suggesting that the Earth system has been operating under low carbon dioxide levels throughout the Pleistocene.

According to Yhang, humans evolved in a low-carbon-dioxide environment, making it an open question just how humans will evolve and be affected by today’s unprecedented levels of carbon dioxide.

Image credit: Rich via Flickr

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