Estimating the biogenic enhancement factor of weathering using an inverse viability method

• Published in: Ecological modelling 2008-08, Vol.216 (2), p.245-251
• Main Authors: von Bloh, Werner, Bounama, Christine, Eisenack, Klaus, Knopf, Brigitte, Walkenhorst, Oliver
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Biological and medical sciences; Cambrian explosion; Fundamental and applied biological sciences. Psychology; General aspects. Techniques; Global carbon cycle; Methods and techniques (sampling, tagging, trapping, modelling...); Viability theory; Weathering
• ISSN: 0304-3800; 1872-7026
• DOI: 10.1016/j.ecolmodel.2008.03.005

To determine the influence of the biosphere on weathering we use a dynamic model of the global carbon cycle. It takes into account the most important processes for the long-term evolution of the Earth. The model is solved under a slowly changing environment of increasing solar luminosity and volcanic activity and continental area. By comparing the model results for the global average temperature with data derived from δ 18O values from cherts it is possible to quantify the biogenic enhancement factor of weathering. For this purpose a newly developed inverse viability method is applied, which allows for calculating the range of possible biogenic enhancement factors consistent with the data. We find that in the Precambrian the weathering was 5.4 times lower than in the Phanerozoic era. This supports the hypothesis that the Cambrian explosion was caused by a positive feedback between the spread of biosphere, increased silicate weathering, and a consequent cooling of the climate.