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We humans have officially entered unknown territory. Over the course of some 2.5 million years, our species has walked on Earth. Never before have we endured such an atmosphere.
New research on ancient soils has now confirmed that the levels of carbon dioxide of the last sixty years are the highest in human history.
Throughout the Pleistocene period – which began 2,580,000 years ago – the authors discovered concentrations of CO2 were, on average, about 250 parts per million.
Yet over the last sixty or so years, this coherence has rapidly faded away. Today, the results suggest that our planet reached 415 ppm for the first time in 2.5 million years.
"According to this research, from the very first Homo erectus, which currently ranges from 2.1 to 1.8 million years ago and until 1965, we lived in a low carbon dioxide environment – concentrations were less than 320 parts per million, "says geoscientist Yige Zhang of Texas A & M University.
"So, this current environment rich in carbon dioxide is not just an experience for the climate and the environment – it's also an experience for us, for ourselves."
To know where we are going, we must first know where we went. The study of past climates, Zhang says, can help provide some of this perspective and, hopefully, help us navigate our uncertain future.
Because they trap tiny air bubbles, ice cores are often used by climatologists as historical CO archives.2 levels in the atmosphere of our planet. But these samples only date back hundreds of thousands of years and not millions.
To dive deeper into the history of the Earth, Zhang and his colleagues turned to the ground. As a natural part of the carbon cycle on Earth, the soil creates carbonates as it forms and these minute traces can be useful as indicators of past climate.
By analyzing the carbonates in the fossil soils of the Loess Plateau in China, the team was able to rebuild the CO2 levels of there are millions of years.
"The Loess Plateau is an incredible place to see the accumulations of wind and wind dust and soil," says Zhang.
"The first dusts identified on this shelf date from 22 million years ago, so the recordings are extremely long."
While it is true that soil carbonates are only a substitute for ancient climates, the results of the Loess Plateau seem to correspond to other estimates, which were made using ice cores and blue ice registers.
Zhang and his team, however, are still not satisfied. They plan to perfect their soil analysis techniques to further improve their estimates, possibly using this technique on soils aged 23 million years.
"The past is the key to our future," Zhang said L & # 39; eagle.
"The Earth has a long history and many things related to climate, life and the environment have changed. (…) The paleoclimate is important for us to get to know the past and can to be able to predict the future. "
The results were published in Nature Communications.
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