The Phanerozoic pCO2 and pO2 has been elegantly calculated by Dr. Robert Berner using a long-term C cycle model called GEOCARB. The fundamental of the model is that silicate weathering acts as a negative feedback to the climate system, i.e. as pCO2 level goes up, more silicate weathering, hence drawing down pCO2. Feedback loops within the dynamic system defined by tectonics, climate and erosional surface processes. There are two feedback loops; a direct path (I) whereby tectonics increases erosion rates by increasing elevation, relief and drainage basin areas and an indirect loop (II), whereby increased elevation induces increased erosion rates through changes in climate. Climate change is in the form of enhanced precipitation or lower temperatures, which lead to glaciation. In each case, there is feedback in the tectonic response to surface mass redistribution. More complex processes and pathways are likely to exist.
Some related knowledge is described here: http://pangea.stanford.edu/~dpollard/NSF/main.html
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Ying CuiI'm a geoscientist doing research on extreme environmental change and its impact to biodiversity in the geologic past. ArchivesCategories |