Sensitivity of Climate Variability to Anthropogenic and Natural Drivers during the Last Millennium Proposal Identifier: GC10-293

The investigators plan a suite of coupled atmosphere-ocean model experiments from 850 AD to 1850. First, a simulation including solar, volcanic, orbital, and greenhouse-gas forcings, land use changes, will be completed. This experiment will directly link in with other pre-Industrial experiments being completed as part of IPCC AR5 - using the same model and resolution as IPCC AR5 experiments - and it will be submitted to the PMIP3 last millennium program. Next, six ensembles of 5 members each will be performed to assess the relative impact of each of the climate forcings. Simulations include amplification of solar effects through a stratospheric ozone response. Global mean trends in surface temperature are expected to have a clear forced component, though internal variability will also have a large role, particularly at the regional scale. Previous work by this group (e.g., Shindell et al., 2001b;Shindell et al., 2004a) and data analyses have indicated that there may be a significant annular mode response to some forcings. The proposed experiments will be used to determine the magnitude of the predictable signal at

regional scales over multi-centennial time periods.