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Zusammenfassung:
It has been hypothesized that predecessors of today’s bryophytes significantly increased
global chemical weathering in the Late Ordovician, thus reducing atmospheric CO2
concentration and contributing to climate cooling and an interval of glaciations. Studies that
try to quantify the enhancement of weathering by non-vascular vegetation, however, are
usually limited to small areas and low numbers of species, which hampers extrapolating to
the global scale and to past climatic conditions. Here we present a spatially explicit modelling
approach to simulate global weathering by non-vascular vegetation in the Late Ordovician.
We estimate a potential global weathering flux of 2.8 (km3 rock) yr1, defined here as
volume of primary minerals affected by chemical transformation. This is around three times
larger than today’s global chemical weathering flux. Moreover, we find that simulated
weathering is highly sensitive to atmospheric CO2 concentration. This implies a strong
negative feedback between weathering by non-vascular vegetation and Ordovician climate.
