ibclogo XVI International Botanical Congess


Abstract Number: 4040
Session = 12.16.3


PLANTS, ROCK WEATHERING, AND PALEOZOIC CLIMATE CHANGE


Robert A. Berner, Dept. of Geology, Yale University


Theoretical calculations have shown that the rise of deeply-rooted vascular land plants during the Devonian should have had an appreciable effect on atmospheric CO2 because plants should accelerate the uptake of CO2 via the weathering of Ca and Mg silicates. We have studied the quantitative role of plants in accelerating weathering in three modern environments. Results, when combined with those of other studies, indicate that weathering is accelerated by higher plants by factors of from three to ten. Use of these values results in a very large calculated drop in atmospheric CO2 level during the Devonian that agrees with independent estimates based on the study of paleosols and stomatal density. This large drop should have induced greenhouse cooling that initiated the major glaciations of the Carboniferous and Permian.


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