The best of EcoWatch, right in your inbox. Sign up for our email newsletter!
Human Ancestors Evolved in a Low-Carbon World
By Tim Radford
For the entire 2.5 million years of the Ice Age epoch called the Pleistocene, it was a low-carbon world. Atmospheric carbon dioxide hovered around 230 parts per million. Not only did Homo sapiens evolve on a low-carbon planet, so did Homo erectus and most other human species now known only from fossil evidence in Europe and Asia.
And this long history of a planet kept cool and stable by low levels of greenhouse gas in the atmosphere continued long after the discovery of fire, the Stone Age, the Bronze Age, the Iron Age, the fall and rise of empires and the Industrial Revolution.
Only in 1965 did carbon dioxide levels pass 320 ppm, after a century of exploitation of fossil fuels that released ancient carbon back into atmospheric circulation.
By 2019, the carbon dioxide concentration in the atmosphere had tipped 410 ppm and is still rising. In less than a century, human action had raised planetary average temperatures by around 1°C. At present rates, this average could reach 3°C by the end of this century.
Researchers have known for a century that humans emerged in a cooler world, but much of the story of the distant past was based on the evidence of fossils and sedimentary rocks. The latest research pushes the detailed atmospheric carbon dioxide accounting back to at least 2.5 million years.
Researchers report in the journal Nature Communications that they studied the pattern of carbon isotope readings preserved in the deep yellow soils of China's Loess Plateau. What they found confirmed 800,000 years of annual evidence from the ice cores of Antarctica and Greenland – and far beyond that limit.
The wind-blown Loess of China dates back to at least 22 million years and each successive layer carries isotope evidence that can be read as testimony to the atmospheric conditions in which the soils were laid down.
The latest find confirms that the normal state of the planet during human evolution was cool, with low levels of atmospheric carbon. Homo erectus was the first known human predecessor to exploit fire, systematically fashion stone hand axes, and to leave Africa for Asia and Europe.
"According to this research, from the first Homo erectus, which is currently dated to 2.1 to 1.8 million years ago, we have lived in a low-carbon environment – concentrations were less than 320 parts per million," said Yige Zhang, a geoscientist at Texas A&M University in the U.S., who worked with colleagues in Nanjing, China and the California Institute of Technology.
"So this current high carbon dioxide experiment is not only an experiment for the climate and the environment – it's an experiment for us, for ourselves."
"This is definitely further evidence that fossil fuels and anthropogenic activity actually has fundamentally changed the climate." In my 1st @EcoWatch post today, studies show the speed and scope of the #ClimateCrisis is unique in the last 2,000 years: https://t.co/SdL04YZStu— Olivia Rosane (@orosane) July 25, 2019
Reposted with permission from our media associate Climate News Network.
EcoWatch Daily Newsletter
By Genna Reed
The EPA announced last week that it is issuing a preliminary regulatory determination for public comment to set an enforceable drinking water standard to two of the most common and well-studied PFAS, PFOA and PFOS.
This decision is based on three criteria:
- PFOA and PFOS have an adverse effect on public health
- PFOA and PFOS occur in drinking water often enough and at levels of public health concern;
- regulation of PFOA and PFOS is a meaningful opportunity for reducing the health risk to those served by public water systems.
By Kieran Cooke
Driving an electric-powered vehicle (EV) rather than one reliant on fossil fuels is a key way to tackle climate change and improve air quality — but it does leave the old batteries behind as a nasty residue.
Finance ministers from the 20 largest economies agreed to add a scant mention of the climate crisis in its final communiqué in Riyadh, Saudi Arabia on Sunday, but they stopped short of calling it a major economic risk, as Reuters reported. It was the first time the G20 has mentioned the climate crisis in its final communiqué since Donald Trump became president in 2017.