Plant fossils reveal that atmospheric CO2 concentrations have not been this high for at least 23 million years and have never risen so rapidly newatlas.com/environment/co…
“Lately we’ve been breaking a lot of records in terms of atmospheric carbon dioxide levels. In 2016 the South Pole became the last region on Earth to exceed a concentration of 400 parts per million (ppm).”
“In May 2019, the Mauna Loa Observatory in Hawaii picked up a record new high of 415.26 ppm. Currently, levels are the highest they've been in all of human history.”
“Higher carbon dioxide levels are linked to climate change, and all the devastation that can bring. Long-term studies have shown a sharp spike from the early 19th century onwards – “coincidentally” right around the time of the Industrial Revolution.”
“To see just how bad things may be, we need to look to the past. Our direct records go back a few hundred years, but it gets murky before that. Drilled ice cores give us a glimpse as far back as 2.7 million years – and unfortunately, revealed that levels were <300 ppm back then.”
“... researchers at the University of Louisiana set out to look even further back in time, stretching 23 million years back. The team managed this by examining fossil remains of ancient plants.”
“When plants grow, they take in CO2 from the atmosphere and their tissues retain certain stable isotopes of carbon – specifically, carbon-12 and carbon-13. We can study the amounts of these isotopes in plant fossils and determine the concentration of CO2 that the plants grew in.”
“Using this method, the researchers found that throughout this 23-million-year period CO2 levels mostly fluctuated between around 230 ppm & 350 ppm. That’s far less than modern levels. They also found no increase in that time as sharp as the climb we’re currently experiencing.”
