![]() This impact can be unraveled by a better understanding of the relationship between the paleo-atmospheric CO 2 concentration (paleo- atm) and ancient climate change.Ī lot of research has involved the estimation of paleo- atm to understand the correlation between CO 2 and global warming. Estimating the impact of high CO 2 concentration on global environmental systems is the first step to propose solutions for the present global climate change. The 5 th report of IPCC concluded that the present positive radiative forcing is unequivocally caused by anthropogenic increases in atmospheric CO 2 concentration and that it influences the climate. Our results also indicated that from middle Miocene to Pleistocene, global CO 2 level decreased by more than 50 ppmv, which may suggest that CO 2 decrease and temperature decrease are coupled.Ĭarbon dioxide (CO 2) is an important greenhouse gas that influences the surface temperature of the Earth. ![]() ![]() According to former research, this is a time when global temperature decreased sharply. According to this research, atmospheric CO 2 concentration was stabile around 330–350 ppmv in the middle and late Miocene, then it decreased to 278–284 ppmv during the Late Pliocene and to 277–279 ppmv during the Early Pleistocene, which was almost the same range as in preindustrial time. Thus, based on the stomatal index of fossilized Metasequoia needles, we reconstructed a history of atmospheric CO 2 concentrations from middle Miocene to late Early Pleistocene when the climate changed dramatically. However, the lack of CO 2 evolution curves estimated from a single terrestrial proxy prevents the understanding of climatic and environmental impacts due to variations in data. The change in ancient atmospheric CO 2 concentrations provides important clues for understanding the relationship between the atmospheric CO 2 concentration and global temperature.
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