Burning Planet by Scott Andrew C.;

Author:Scott, Andrew C.; [Scott, Andrew C.]
Language: eng
Format: epub
Publisher: Oxford University Press, Incorporated
Published: 2018-01-30T00:00:00+00:00

It was a long walk down to the main seam to get rock samples—three lots of them, for petrography, for the isotope geochemistry, and for palynology—to identify vegetation from microscopic pollen and spores. It was hard and often dirty work, but we collected a significant amount of material. Fortunately we had arranged for at least some of it to be driven out of the mine.

As I write this, our research is not yet complete, but we have made progress. New ways to interpret the temperature at the time have indicated that lands at 48°N in this part of the early Eocene experienced mean annual temperatures ranging from 23°C to 26°C.14 The evidence from Schöningen indicates that fire was significant in the lower part of the sequence. In general, although charcoal abundance was low relative to previous high-fire worlds such as the Cretaceous, wildfire activity was higher than today during the warmest parts of the Paleogene—that is, during the PETM interval covering the end of the Paleocene and earliest part of the Eocene.15 By this time, as we noted, atmospheric oxygen levels had stabilized to modern values, and precipitation and humidity became the main control on wildfire. Increased rainfall, encouraging lush vegetation, followed by droughts, would have created an environment rich in dry fuel in which wildfires could easily propagate if humidity became low enough.

A few million years into the Eocene, by around 50 million years ago, charcoal abundance falls to levels similar to those found in modern peats. The transition to the modern low-fire world appears to have occurred within the early Eocene, and records from across the globe confirm that by 45 million years ago wildfire systems operated much as they do today (Figure 49).

Figure 49. Phases of fire system development through geological time, showing the major innovations in plant evolution and showing the change from a low-fire to high-fire world, and to the current fire world.

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