W. von Bloh, S. Franck, C. Bounama, and H.-J. Schellnhuber

Geomicrobiology Journal 20(5), 501-511 (2003)

Potsdam Institute for Climate Impact Research (PIK), Telegrafenberg, P.O. Box 60 12 03, 14412 Potsdam, Germany.

Abstract

A dynamic model of the global carbon cycle is used to determine the influence of biotic amplification of weathering on the overall stability of the biosphere. It takes into account the most important processes for the long-term evolution of the Earth. The model is solved under a slow changing environment of increasing luminosity and volcanic activity and continental area. We find that for large enough amplification factors the system has two stable states, the abiotic and biotic solution. Furthermore, this leads to an extension of the life span of the biosphere by 0.7 Gyr compared to previous studies underestimating the effect of biogenic enhancement of weathering. It can be shown that the biosphere is resilient to random perturbation of the global carbon cycle for the next 0.5-1.0 Gyr.

Keywords: Global carbon cycle, weathering, stability analysis, photosynthetic productivity