http://www.sciam.com/article.cfm?cha...4583414B7F4945

Model Predicts Future Heat Waves Will be More Intense

Last year's hot weather in France made August miserable for most
citizens and claimed thousands of lives. Climate modeling results
published today in the journal Science indicate that heat waves at the
end of the 21st century will be more severe, more frequent and longer
lasting than those of recent years.

Gerald Meehl and Claudia Tebaldi of the National Center for
Atmospheric Research (NCAR) utilized the Parallel Climate Model to
investigate the behavior of future heat waves. "Extreme weather events
will have some of the most severe impacts on human society as climate
changes," Meehl remarks. The researchers ran the model for both the
20th century, using data from 1961 to 1990, and the 21st, predicting
events for 2080 to 2099, assuming little in the way of policy
intervention for greenhouse gas emissions.

Using Paris and Chicago as focal points for Europe and North America,
respectively, the team determined that the atmospheric circulation
pattern seen during heat waves is likely to become more pronounced as
greenhouse gas concentrations rise. For example, heat events in
Chicago currently last between 5.39 and 8.85 days, but the new
findings indicate that they will stretch to between 8.5 and 9.24 days
in the future. Paris, meanwhile, might experience heat waves lasting
up to 17 days instead of between eight and 12. "This study provides
significant insight into the complex response of global climate to
possible future worldwide economic and regulatory policies," comments
Cliff Jacobs, atmospheric science program director for the National
Science Foundation (NSF). "The societal implications of this study
need to be further explored." --Sarah Graham