Session: Cross-cutting Group 2 (Paleovar, Past to future, Data assimilation)
Author: Ryouta O'ishi / email@example.com / Atmosphere and Ocean Research Institute, the University of Tokyo
Co-author: Masakazu Yoshimori, Faculty of Environmental Earth Science, Hokkaido University;
Ayako Abe-Ouchi, Atmosphere and Ocean Research Institute, the University of Tokyo;
Past warm periods are induced by both higher atmospheric CO2 concentration and the change of Earth’s orbit through different temporal and spatial pattern of downward shortwave radiation. Previous studies revealed that vegetation change in high latitude (e.g. from tundra to forest) in warm climate strengthens a polar amplification. This is due to lower vegetation albedo of forest than tundra, snow-albedo feedback caused by early snow melt due to forest coverage and ocean heat release in autumn and winter. To reveal the mechanisms of orbit-induced warming case (6ka) and CO2-induced warming cases (2xCO2 and 4xCO2), we apply a feedback analysis method (Yoshimori et al. 2014) on several climate simulations by a GCM with vegetation feedback. We also discuss the difference of feedback mechanisms in the orbit induced case and CO2-induced case, especially focusing on interseasonal warming mechanisms caused by vegetation feedback in the high latitude and its contribution to the polar amplification.