3:30 PM - 3:45 PM
[PPS08-01] Effects of thermal evolution and continental growth on climate evolution of Earth-like planets
Keywords:Climatic evolution, Carbonate-silicate geochemical cycle
In this study, we investigate the effects of CO2 degassing history due to thermal evolution of mantle, and of size and distribution of continents on the climate of the Earth-like planet in terms of carbonate-silicate geochemical cycle. We also investigated the climatic evolution of the Earth-like planet, considering the continental growth, with a parameterized convection model.
The dependence of the mantle heat flow on the average mantle temperature is usually represented by the exponent of the Nusselt-Rayleigh number power-law relation (b). When the exponent, b, becomes 0, the dependency of the heat flow on the mantle temperature becomes weak and independent at b=0. The CO2 degassing rate is lower for b=0 than the case for b=1/3 (the value used in the traditional models) through the planetary history. As a result, assuming a constant size of continents, the Earth-like planet is colder for b=0 than the case for b=1/3 through the history, and even in the snowball climate in its early stage. The climate is, however, warm when the continental growth is assumed in the model. In this case, the results are similar to those of the case for b=1/3 with/without continental growth. The continental growth is, therefore, a very important factor which controls climate evolution of the Earth-like planet, in addition to the evolution of the CO2 degassing via volcanism.