HR: 09:00h
AN: U51B-05    [Abstracts]
TI: Linking glacial and future climate through ensembles of GCM simulations
AU: * Hargreaves, J C
EM: jules@jamstec.go.jp
AF: FRCGC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AU: Abe-Ouchi, A
EM: abeouchi@ccsr.u-tokyo.ac.jp
AF: FRCGC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AU: Annan, J D
EM: jdannan@jamstec.go.jp
AF: FRCGC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan
AB: Relatively few GCMs have been integrated for both doubled carbon dioxide (2xCO2) and Last Glacial Maximum (LGM) conditions, making it hard to quantify any relationship between these two climates in the models. Here we use ensembles of the MIROC3.2 GCM with varied parameters, whose members all agree reasonably well with present day climatology. By running the ensembles for a variety of experiments, including LGM and 2xCO2 we can explore some of the uncertainties in the relationship between these two climates on global and regional scales. The MIROC3.2 model shows an asymmetry in its response to changes in greenhouse gases, with 80% of the ensemble having a weaker cooling for low CO2 than warming for high CO2. This asymmetry would suggest that direct estimates of climate sensitivity from the LGM based on first-order energy balance considerations could be underestimated by the order of half a degree. Additional analysis of the differences in climate sensitivity at LGM and pre-industrial climate states is now underway and first results will be presented. Regionally, our results lend support to the idea that Antarctic is a useful place to look for historical data which can be used to validate models used for climate forecasting of future greenhouse gas induced climate changes, at regional and global scales. Good results may also be obtainable using tropical temperatures, particularly those over the ocean. Our result for Greenland is not so strong, possibly due to difficulties in accurately modelling the sea ice extent.
DE: 1610 Atmosphere (0315, 0325)
DE: 1621 Cryospheric change (0776)
DE: 1626 Global climate models (3337, 4928)
DE: 1637 Regional climate change
DE: 3315 Data assimilation
SC: Union [U]
MN: 2007 Fall Meeting