Project: IPCC Data Distribution Centre : Second Assessment Report data sets - The Intergovernmental Panel on Climate Change (IPCC) has been established by WMO and UNEP to assess scientific, technical and socio-economic information, relevant for the understanding of climate change, its potential impacts and option for adaption and migration. Projection of future trends for a number of key variables are provided through this section of the DDC (http://ipcc-data.org/sim/gcm_clim/IS92A_SAR/). This information contained in either IS92 emission scenarios (IPCC 1992) or published model studies using data from these scenarios. Six alternative IPCC scenarios (IS92a to f) were published in the 1992 Supplementary Report to the IPCC Assessment. These scenarios embodied a wide array of assumption affecting how future greenhouse gas emissions might evolve in the absence of climate policies beyond those already adoped. Model experiments, also using different forcing scenarios, were calculated at other modeling centres. Leggett, J., W.J. Pepper and R.J. Swart, 1992: Emissio ns Scenarios for IPCC: An Update. In: Climate Change 1992. The Supplementary Report to the IPCC Scientific Assessment [Houghton, J.T., B.A. Callander and S.K. Varney (eds.)], Cambridge University Press, Cambridge, UK, pp. 69-95. _ Model experiments, also using IS92a forcing scenarios, were calculated at other modeling centres: NCAR (National Center for Atmospheric Research, USA) GFDL (Geophysical Fluid Dynamics Laboratory, USA) CCCma (Canadian Centre for Climate Modelling and Analysis, Canada) CSIRO (Commonwealth Scientific and Industrial Research Organisation, Australia) Hadley Centre (Met Office Hadley Centre, UK) CCSR (Atmosphere and Ocean Research Institute, the University of Tokyo, Japan) DKRZ (German Climate Computing Center, Germany) MPI-M (Max Planck Institute for Meteorology, Germany) and more. Summary: The control integration, in which the atmospheric forcing is kept constant, simulates a period over 240 years (1860-2099) in length. Control experiment (CTL): In CTL, greenhouse gases and aerosols are prescribed exactly as in the uncoupled ECHAM-4 model. The concentrations of carbon dioxide, methane and nitrous oxide are fixed at the observed 1990 values (IPCC'90, Table 2.5), the concentrations of the industrial gases (CFC's and others) are set to zero, while ozone and aerosols are prescribed as climatological distributions. There is no sulfur cycle in CTL. After a 100-year spin up the model was run, with constant flux adjustment, for another 240 years (Roeckner et al., 1998). The climatology constructed from this 240-year CTL run serves as a reference for the time-dependent forcing experiments GHG, GSD and GSDIO (EH4OPYC_22670GHG_,EH4OPYC_22697GSD_, EH4OPYC_22723GSDIO_). These data represent monthly averaged surface values of selected variables for the IPCC-Data Distribution Centre. (see also http://www.ipcc-data.org/ )