357. High-carbon ice age mystery solved –
March 11, 2010 § Leave a comment
How come a big ice age happened when carbon dioxide levels were high? It's a question climate sceptics often ask. But sometimes the right answer is the simplest: it turns out CO2 levels were not that high after all.
The Ordovician ice age happened 444 million years ago, and records have suggested that CO2 levels were relatively high then. But when Seth Young of Indiana University in Bloomington did a detailed analysis of carbon-13 levels in rocks formed at the time, the picture that emerged was very different. Young found CO2 concentrations were in fact relatively low when the ice age began