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New Climate System Model Shows Earth's Surface Temperature RisingThe earth's mean surface temperature is expected to rise .2 degree Kelvin (.36 degree Fahrenheit) per decade over the next four decades, according to a new modeling study. The study uses a climate system model (CSM-1) developed at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. NCAR's primary sponsor, the National Science Foundation (NSF), funded the research. Results were derived from a two-century simulation of earth's climate. Other results expected by the end of the year include information on climate changes related to precipitation, cloudiness, and large-scale run-off. The CSM-1 is a physical climate model which uses atmosphere and ocean general-circulation models, a sea-ice model, and a land-biophysics and simple hydrology model, explains Cliff Jacobs, NSF program manager for NCAR. It is one of the few current climate models that maintain a stable surface climate over hundreds of years without the need for artificial corrections. The climate simulations were driven by observed changes in atmospheric trace-gas concentrations for the period 1870 to 1990 and two projected trace-gas scenarios for the period 1990 to 2100. The greenhouse gases included in the model are carbon dioxide, methane, nitrous oxide and chlorofluorocarbons 11 and 12. Emissions of sulfur dioxide (SO2) resulting from human activity are also included, with projected increases over time. Natural SO2 emissions were assumed to be constant. SO2 is important because it is converted in the atmosphere into sulfate aerosol, which reflects some sunlight back into space and may slow or reverse global warming trends in certain regions, according to NCAR scientist Byron Boville.
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