Reconstruction of glacial-interglacial variations of greenhouse gases from a Greenland deep ice core, NGRIP

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In order to reconstruct variations of atmospheric CH_4, N_2O, CO_2 and O_2 concentrations, δ^<15>N of N_2, δ^<18>O of O_2, and air content for the last 130 Kyrs, we analyzed the North-GRIP deep ice core from Greenland using a wet air extraction technique. We also determined ice age and age differences between ice and occluded air based on the results of δ^<18>O of ice and an accumulation model. After correcting for a gravitational effect occurred due to molecular diffusion in firn, detailed temporal variations of all the abovementioned factors were deduced. Furthermore, we also discussed the similarity and differences between variation histories of all factors in north and south polar regions, by comparing the results obtained from the North-GRIP core and the Dome Fuji deep ice core, Antarctica. Especially interesting results derived in this study are that 1.the CH4 concentration was always higher in the north polar region in the south polar region, and those concentration differences … More depended on temperature, except for Holocene, 2.the CO_2 concentrations from the North-Grip core were apparently higher than those from the Dome Fuji core, suggestion that CO2 was newly produced by reacting with impurities during storage of air in ice in Greenland, 3.the N_2O concentrations from the North-Grip and Dome Fuji ice cores were fairly stable for Holocene, but quite variable in the glacial period, 4.the O2 concentrations from the North-Grip and Dome Fuji ice cores were extremely low, suggesting that the process of air occlusion into ice at the bottom of firn is very complex, and 5.that temporal variations of air content from both cores were similar to each other, but such variations are in conflict with our present knowledge, which may be related to incident solar radiation. By analyzing the temporal variations of CH4 concentration differences obtained from the North-Grip and Dome Fuji ice cores using a 3-box model consisting of northern and southern high latitudes and low latitude, we also succeeded in elucidating where was responsible for the north-south concentration differences over the glacial interglacial period. Less