The geological record shows that the Earth’s carbon cycle suffered over 30 major disruptions during the Phanerozoic.  Some of the biggest ones were accompanied by mass extinctions.  Dan Rothman analyzed these disruptions to find a pattern governing their magnitude and duration.  As he explains in the podcast, this pattern is suggestive of a non-linear dynamical system that, once excited, undergoes a large excursion before returning to where it was.  Could we be exciting such a disruption now?
He shows that the mass of anthropogenic carbon emissions forecast by the end of the century is about the same as the mass of carbon dioxide outgassed by the massive volcanism that generated the portion of the Deccan Traps deposited just before the end-Cretaceous extinction.  This leads him to hypothesize that, while the Chixclub meteor impact may have been the direct cause of the extinction, the disruption of the carbon cycle caused by the outgassing of CO₂ during this prolific series of eruptions contributed to the environmental change associated with mass extinction. 
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