New method: Only 600 ppm CO2 in the atmosphere when forests appeared

December 21, 2022By Tais W. DahlOutreach
The first vascular plants on Earth were small shrub-like vegetation. When trees evolved ~385 million years ago, the CO2 level in the atmosphere did not change much and remained at a far lower levels than previously thought (2000-8000 ppm). With a new mechanistic proxy calibrated in modern club mosses, we have discovered that the atmospheric [...]