Over the last 200 years, humans have engaged in an unprecedented experiment with the climate. We have increased CO2 by over 100 ppm. You can see this dramatic change marked in red on the right side of the graph above. Our unprecedented and dangerous experiment has brought CO2 up slightly above the lowest levels in earth’s history.
One can hardly imagine the intense heat and extreme weather during the Ordovician Ice Age, with CO2 levels 10 times higher than at present.
A Late Ordovician ice sheet in South America: Evidence from the Cancañiri tillites, southern Bolivia
Detailed mapping and facies analysis of a thick succession of diamictites of the Upper Ordovician Cancañiri Formation in southern Bolivia has revealed a glacioterrestrial origin for these sediments. The Cancañiri diamictites were deposited during three advances of a temperate, grounded ice sheet.