T126 What Good Are (Fossil) Plants Anyway? New Methods for Investigating Old Problems

Sunday, 5 October 2008
8:00 AM - 12:00 PM

New Limits for Combustion in Low Oxygen Redefine Paleoatmospheric Predictions for the Mesozoic

Paper number: T126-11
Program: Technical Sessions
Time: 10:25 AM – 10:40 AM

Authors

Abstract

Numerous studies have sought to test combustion under varying concentrations of oxygen however, none have been able to assess the limits of combustion within a fully controlled and realistic atmospheric environment. Experimental burns were performed at 20 degrees centigrade at oxygen concentrations ranging from 9 to 21%, and at ambient and high (2000ppm) carbon dioxide, in a new experimental atmospheres and climate facility, equipped with a thermal imaging system and full atmospheric, temperature and humidity control. Our data reveal that the lower oxygen limit for combustion within the long-held “fire window” (12-35%) should be increased from 12 to 15%. These results, coupled with a new record of Mesozoic paleowildfires are incompatible with the prediction of prolonged intervals of super-low atmospheric oxygen levels (10-12%) in the Mesozoic. Paleowildfire provides a key proxy for testing super-low oxygen events in the geological record and must be studied in order to test hypotheses suggesting that short-term super-low oxygen periods drove faunal and floral diversity loss across major mass extinction events.