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19 February 2003

Temperatures keep rising

After the cold, difficult weather during these past few months, it is hard to imagine that winter temperatures in the polar regions of the world could rise as much as 10°C in the next hundred years if no efforts are made to control production of carbon dioxide, methane, and other gases, according to computations taken from powerful computer models.

"With projections to the year 2100, we can show what will happen if we continue with business as usual—if we don't do anything to curb emissions of greenhouse gases," said Warren M. Washington, senior research scientist for the National Center for Atmospheric Research (NCAR) and a speaker at the AAAS Annual Meeting in Denver.

Noting that concentrations of carbon dioxide and methane did not start to increase significantly until the twentieth century, Washington demonstrated worldwide projections for average temperature in 2050 and 2090.

"The greatest warming takes place in the winter hemisphere and is strongly influenced by the retreat of snow and ice in high latitudes," said Washington. "The range of [computer] models for global climate change at the end of the century is 1.5° to 6°C, with most of the models in the range of 2° to 4°. In the polar regions, the changes are of the order of 8° to more than 10° in the wintertime of the years."

The computer predictions, produced by the NCAR Parallel Climate Model and by other computer systems, are made by interpreting data gathered on sea ice, land vegetation, ocean, and atmospheric components of the climate system and by creating an interactive system for understanding how they work together to influence the earth's climate.

"The atmospheric, ocean, and sea ice components make use of the fundamental laws of physics," Washington said. "In the atmosphere, for example, equations describe the wind, temperature, density, and pressure relationships. Climate models require supercomputer capability to solve the complex interactive mathematical equations."