Humankind did not live with a high-carbon dioxide atmosphere until 1965

Humankind did not live with a high-carbon dioxide atmosphere until 1965
Analyzing Paleogenic carbonates found in the ancient soil from the Loess Plateau, scientists reconstructed the Earth’s carbon dioxide levels. Credit: Dr. Yige Zhang

Humans have never before lived with the high carbon dioxide atmospheric conditions that have become the norm on Earth in the last 60 years, according to a new study that includes a Texas A&M University researcher.

Titled "Low CO2 levels of the entire Pleistocene Epoch" and published in Nature Communications today, the study shows that for the entire 2.5 million years of the Pleistocene era, averaged 250 parts per million. Today's levels, by comparison, are more than 410 parts per million. In 1965, Earth's atmospheric concentrations exceeded 320 parts per million, a high point never reached in the past 2.5 million years, the study shows.

"According to this research, from the first Homo erectus, which is currently dated to 2.1 to1.8 million years ago, until 1965, we have lived in a low- dioxide environment—concentrations were less than 320 parts per million," said Yige Zhang, a co-author of the research study and an assistant professor in the Department of Oceanography in the College of Geosciences. "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."

Carbon dioxide is a that contributes to the warming of Earth's atmosphere, and is considered a driver of global climate change, Zhang said.

"It's important to study atmospheric CO2 (carbon dioxide) concentrations in the geological past, because we know that there are already climate consequences and are going to be more climate consequences, and one way to learn about those consequences is to look into Earth's history," Zhang said. "Then we can see what kind of CO2 levels did we have, what did the climate look like, and what was the relationship between them."

Jiawei Da, Xianqiang Meng and Junfeng Ji, all of Nanjing University in China, and Gen Li of the California Institute of Technology co-authored the research.

The scientists analyzed carbonates from the Loess Plateau in central China to quantify ancient atmospheric carbon dioxide levels as far back as 2.5 million years ago. Climate scientists often use ice cores as the "gold standard" in physical climate records, Zhang said, but ice cores only cover the past 800,000 years.

Analyzing Paleogenic carbonates found in the ancient soil, or paleosols, from the Loess Plateau, the scientists reconstructed the Earth's carbon dioxide levels.

"The Loess Plateau is an incredible place to look at aeolian, or wind, accumulation of dust and soil," Zhang said. "The earliest identified dust on that plateau is from 22 million years ago. So, it has extremely long records. The layers of loess and paleosol there contain soil carbonates that record atmospheric carbon dioxide, if we have very careful eyes to look at them."

"Specifically, carbonates formed during soil formation generally reach carbon isotopic equilibrium with ambient soil CO2, which is a mixture of atmospheric CO2 and CO2 produced by soil respiration," said Nanjing University's Jiawei Da. "Through the application of a two-component mixing model, we can reconstruct paleo-CO2 levels using carbonates in fossil soils."

Using those materials and the techniques, the researchers constructed a carbon dioxide history of the Pleistocene.

"Our reconstructions show that for the entire Pleistocene period, carbon dioxide averaged around 250 parts per million, which is the same as the last 800,000 years' values," Zhang said.

"Our paleosol-based CO2 estimates are in line with snapshots of early-Pleistocene CO2 retrieved from Antarctic old, blue ice, suggesting that the Earth system has been operating under low CO2 levels throughout the Pleistocene," said Junfeng Ji of Nanjing University.

We evolved in a low-carbon-dioxide environment, Zhang said, and how humans will evolve and be affected by today's carbon- levels is yet to be seen.


Explore further

Heat-trapping carbon dioxide levels in air hit another high

More information: Jiawei Da et al, Low CO2 levels of the entire Pleistocene epoch, Nature Communications (2019). DOI: 10.1038/s41467-019-12357-5
Journal information: Nature Communications

Citation: Humankind did not live with a high-carbon dioxide atmosphere until 1965 (2019, September 25) retrieved 20 October 2019 from https://phys.org/news/2019-09-humankind-high-carbon-dioxide-atmosphere.html
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Sep 25, 2019
Plants die at under 170 ppm. Navy submariners are allowed 2000 ppm.

More Alarmist BS from phys .org

Sep 25, 2019
Living up to your name I see. So old and set in your ways you will keep denying the blatantly obvious until the day you die.
Short sighted, selfish, greedy Aholes got the planet into this mess and the best we can do is wait for them to die of natural causes. The next generations will have to ride this out. So unfair.
Better pray you die soon, things are happening much faster than expected and your head might explode from cognitive dissonance.

Sep 26, 2019
^^^^^^
Living up to the jackass with blinders on, I see. Better pray those bus drivers are keeping an eye out for you.

Sep 26, 2019
Building environments often run up to 1000 ppm CO2; I'd imagine that small, smokey huts with wood fires might have had even higher concentrations than our modern, HVAC-ventilated buildings. Passenger aircraft in flight run with about 1500 ppm CO2, and can reach 4000 ppm while parked on the tarmac awaiting take-off. So, it isn't like humans have never experienced such high CO2 levels, before; it isn't at all unusual for humans to live in much higher CO2 concentrations.

Sep 26, 2019
The point isn't what the CO2 will do to people directly. It's what it does to the environment, and we've never lived in that environment.

Sep 26, 2019
Our real catastrophy is deforestation. Just think: this year we have three major fires.
These are amazon forests, syberia and south east asia. The area is so huge, millions os sq. miles.

Sep 26, 2019
^^^^^^
Living up to the jackass with blinders on, I see. Better pray those bus drivers are keeping an eye out for you.
Monkey disappointing, we are looking for the super stupid replies from you not the normal boring stupid replies, you have to work for that whopper you know... ;)

Sep 26, 2019
And unfortunately, @atex, this isn't just a problem with deforestation. The carbon sunk in those forests is being released into the atmosphere, compounding the problem, and making it even worse, the Siberian fires are encroaching on the peat bogs where all the methane is sitting waiting to be released.

Sep 26, 2019
At 1000ppm intellectual capacity is measurably affected, adversely.

Sep 26, 2019
"According to this research, from the first Homo erectus, which is currently dated to 2.1 to1.8 million years ago, until 1965, we have lived in a low-carbon dioxide environment—concentrations were less than 320 parts per million,"

Late Eocene ~34 Myr-ago CO2 was averaging 760 ppm. Very fossiliferous, bones found in the Paris Basin. In 1987 it was 350 ppm...the current goal if emissions are lowered. That's 65 ppm or ~500 billion tons. Humans can't handle that. By the time zero emissions is reached it could be 500 ppm.

tpb
Sep 27, 2019
Quote
"We evolved in a low-carbon-dioxide environment, Zhang said, and how humans will evolve and be affected by today's carbon-dioxide levels is yet to be seen."

The answer is any possible CO2 levels in air aren't a problem for humans, we exhale air with 38,000 ppm, so an inhale of 300 ppm or 500 ppm makes no difference.

Sep 28, 2019
Building environments often run up to 1000 ppm CO2; You must have a lot of experience in Facilites Management, or maybe not. Modern HVAC protocol is to monitor CO2 levels to provide fresh air in a building. Guess what? You routinely try to keep it around 600ppm. If you are running at 1000ppm your indoor air quality is lousy.

Sep 30, 2019
Is this nonsense what passes for science nowadays. Of course we have lived in higher CO2 levels. We are currently in a CO2 drought !!

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