Ensemble Simulation of the Last Millenium using the Comprehensive COSMOS Earth System Model ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Ensemble Simulation of the Last Millenium using the Comprehensive COSMOS Earth System Model LAST UPDATE: 3/24/2011 (Original receipt by WDC Paleo) CONTRIBUTOR: Johann Jungclaus, Max Planck Institute for Meteorology IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2011-030 WDC PALEO CONTRIBUTION SERIES CITATION: Ensemble Simulation of the Last Millenium using the Comprehensive COSMOS Earth System Model IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2011-030 NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Jungclaus, J.H., S.J. Lorenz, C. Timmreck, C.H. Reick, V. Brovkin, K. Six, J. Segschneider, M.A. Giorgetta, T.J. Crowley, J. Pongratz, N.A. Krivova, L.E. Vieira, S.K. Solanki, D. Klocke, M. Botzet, M. Esch, V. Gayler, H. Haak, T.J. Raddatz, E. Roeckner, R. Schnur, H. Widmann, M. Claussen, B. Stevens and J. Marotzke. 2010. Climate and carbon-cycle variability over the last millennium. Clim. Past, 6, 723-737. doi:10.5194/cp-6-723-2010 ABSTRACT: A long-standing task in climate research has been to distinguish between anthropogenic climate change and natural climate variability. A prerequisite for fulfilling this task is the understanding of the relative roles of external drivers and internal variability of climate and the carbon cycle. Here, we present the first ensemble simulations over the last 1200 years with a comprehensive Earth system model including a fully interactive carbon cycle. Applying up-to-date reconstructions of external forcing including the recent low-amplitude estimates of solar variations, the ensemble simulations reproduce temperature evolutions consistent with the range of reconstructions. The 20th-century warming trend stands out against all pre-industrial trends within the ensemble. Volcanic eruptions are necessary to explain variations in pre-industrial climate such as the Little Ice Age; yet only the strongest, repeated eruptions lead to cooling trends that stand out against the internal variability across all ensemble members. The simulated atmospheric CO2 concentrations exhibit a stable carbon cycle over the pre-industrial era with multi-centennial variations somewhat smaller than in the observational records. Early land-cover changes have modulated atmospheric CO2 concentrations only slightly. We provide a model-based quantification of the sensitivity (termed γ) of the global carbon cycle to temperature for a variety of climate and forcing conditions. The magnitude of γ agrees with a recent statistical assessment based on reconstruction data. We diagnose a distinct dependence of γ on the forcing strength and time-scales involved, thus providing an explanation for the systematic difference in the observational estimates for different segments of the last millennium. GEOGRAPHIC REGION: Global PERIOD OF RECORD: Last Millennium FUNDING SOURCE: Funding was provided by the ENIGMA project of the Max Planck Society(SJL), the DFG CAWSES Priority Program (NAK, LEV), the DFG Collaborative Research Center 574 (CT), and the WCU program of the Korean Ministry of Education, Science and Technology (SKS). DESCRIPTION: The MILLENNIUM project aims at ensemble simulation of the last millenium (800-2000 AD) using the comprehensive COSMOS Earth System Model. The ESM complex circulation models for the ocean and atmosphere include an interactive carbon cycle. The forcing stems from the most recent reconstructions of solar, volcanic, and orbital variations and land use changes. Scientific objectives of the project are (among others): The discrimination between natural variability and anthropogenic clmate change, the identification of hot-spots of climate change and variability, variations in the atmospheric circulation patterns, and the test of statistical reconstruction methods. More details can be found under (http://www.mpimet.mpg.de/en/wissenschaft/interne-projekte/millennium.html) The data are located at URL: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/gcmoutput/mpi/ It is all monthly means on a 96 x 48 gaussian grid. The data is in netCDF format and split into folders by variable type. Each file contains one variable for one experiment. The directory TEMP2 contains air temperature at 2m in Kelvin. MSLP contains mean sea level pressure at the surface in Pa. TPREC contains total precipitation(or precipitation flux) in kg m-2 s-1. Here are descriptions of the experiments: Experiment ID Length Description mil0001 800-3800 yr. 800 control experiment mil0002 800-2100 land use change only (best guess) experiment mil0005 800-2005 solar forcing only mil0006 800-2005 solar forcing only (scaled to 0.25% amp.) mil0007 800-2100 as mil0002, only biogeochemical influence of land cover changes mil0008 1860-2100 as mil0002, plus fossil fuel emissions mil0009 800-2005 Volcanoes only mil0010 800-2005 full forcing experiment (ensemble member 1) mil0012 800-2005 full forcing experiment (ensemble member 2) mil0013 800-2005 full forcing experiment (ensemble member 3) mil0014 800-2005 full forcing experiment (ensemble member 4) mil0015 800-2005 full forcing experiment (ensemble member 5) mil0021 800-2100 full forcing using solar forcing of Bard (ensemble member 1) mil0025 800-2100 full forcing using solar forcing of Bard (ensemble member 2) mil0026 800-2100 full forcing using solar forcing of Bard (ensemble member 3)