Deep-time evidence of a link between elevated CO2 concentrations and perturbations in the hydrological cycle via drop in plant transpiration
Margret Steinthorsdottir et al., Dept. of Geological Sciences, Stockholm University, SE-106 91 Stockholm, Sweden. Posted online 23 July 2012; doi: 10.1130/G33334.1.
In this manuscript, Margret Steinthorsdottir and colleagues propose a novel mechanistic link between marine and terrestrial mass extinction via atmospheric CO2-driven changes in plant transpiration across the Triassic-Jurassic mass extinction boundary (200 million years ago). This study is the first to calibrate the plant transpiration of an ancient terrestrial ecosystem during a period of high CO2-induced global warming and to link plant physiological forcing to broader environmental degradation and loss of biodiversity through effects on the hydrological cycle. The effect of the current rise in CO2 concentration on the hydrological cycle is receiving increasing attention, and it has been repeatedly suggested (but not tested) that the physiological forcing of atmospheric CO2 (i.e., the effects on plant transpiration) may equal or exceed the effects of the radiative forcing of CO2. The results reported in this paper may not only provide a mechanism to link the effects of rapid rise in atmospheric CO2 concentration and environmental degradation/loss of biodiversity at the Triassic-Jurassic mass extinction boundary, but also may have a significant relevance for the discussion of future impacts of global warming. Plant transpiration responses may thus be of key importance in both past and future climate change, through physiological forcing of the hydrological cycle.
Barrier islands on bedrock: A new landform type demonstrating the role of antecedent topography on barrier form and evolution
J.A.G. Cooper et al., University of Ulster, School of Environmental Sciences, Coleraine BT52 1SA, Northern Ireland, UK. Po
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Geological Society of America