Baseline intrinsic flammability of Earth's ecosystems estimated from paleoatmospheric oxygen over the past 350 million years
Document Type: Journal Article
Author(s): Claire M. Belcher; Jon M. Yearsley; Rory M. Hadden; Jennifer C. McElwain; Guillermo Rein
Editor(s): Karl K. Turekian
Publication Year: 2010

Cataloging Information

  • air temperature
  • biogeochemical cycles
  • biomass
  • carbon
  • combustion
  • deep time
  • duff
  • ecosystem dynamics
  • evolution
  • fire management
  • flammability
  • forest fire
  • humus
  • ignition
  • litter
  • oxygen
  • paleoecology
  • paleofire
  • peat
  • prehistoric fires
  • rate of spread
  • soil organic matter
  • statistical analysis
  • wildfires
  • International
Record Maintained By:
Record Last Modified: February 23, 2019
FRAMES Record Number: 49271
Tall Timbers Record Number: 25613
TTRS Location Status: In-file
TTRS Call Number: Fire File
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.


Atmospheric oxygen (O2) is estimated to have varied greatly throughout Earth's history and has been capable of influencing wildfire activity wherever fuel and ignition sources were present. Fires consume huge quantities of biomass in all ecosystems and play an important role in biogeochemical cycles. This means that understanding the influence of O2 on past fire activity has far-reaching consequences for the evolution of life and Earth's biodiversity over geological timescales. We have used a strong electrical ignition source to ignite smoldering fires, and we measured their self-sustaining propagation in atmospheres of different oxygen concentrations. These data have been used to build a model that we use to estimate the baseline intrinsic flammability of Earth's ecosystems according to variations in O2 over the past 350 million years (Ma). Our aim is to highlight times in Earth's history when fire has been capable of influencing the Earth system. We reveal that fire activity would be greatly suppressed below 18.5% O2, entirely switched off below 16% O2, and rapidly enhanced between 19-22% O2. We show that fire activity and, therefore, its influence on the Earth system would have been high during the Carboniferous (350-300 Ma) and Cretaceous (145-65 Ma) periods; intermediate in the Permian (299-251 Ma), Late Triassic (285-201 Ma), and Jurassic (201-145 Ma) periods; and surprisingly low to lacking in the Early-Middle Triassic period between 250-240 Ma. These baseline variations in Earth's flammability must be factored into our understanding of past vegetation, biodiversity, evolution, and biogeochemical cycles.

Online Link(s):
Belcher, C. M., J. M. Yearsley, R. M. Hadden, J. C. McElwain, and G. Rein. 2010. Baseline intrinsic flammability of Earth's ecosystems estimated from paleoatmospheric oxygen over the past 350 million years. Proceedings of the National Academy of Sciences of the United States of America, v. 107, no. 52, p. 22448-22453.