Much of the world, including the drought-plagued American West, will face more deadly heat waves, intense rainstorms and prolonged dry spells before the end of the century, according to a new climate change study released Thursday.
Focusing not on averages but on extremes, the new research draws on nine climate models to predict what will happen if worldwide greenhouse gases keep increasing.
Longer periods of high heat and heavy rainfall are predicted for nearly all areas by 2080 to 2099. In addition, dry periods will last longer in the Southwestern United States, southern Europe and several other areas, the scientists reported.
"It's the extremes, not the averages, that cause the most damage to society and to many ecosystems," said Claudia Tebaldi, lead author of the report by the National Center for Atmospheric Research in Boulder, Colo., Texas Tech University and Australia's Bureau of Meteorology Research Center.
In California, if the predictions come true, it could mean a triple whammy: more temperatures soaring over 100 degrees, longer rainless periods and more powerful winter storms that could trigger flooding.
"In the future, rising frequency, intensity and duration of temperature extremes ... are likely to have adverse effects on human mortality and morbidity," says the scientists' report, "Going to Extremes," which will be published in the December issue of the journal Climatic Change. "Changes in precipitation-related extremes such as heavy rainfall and associated flooding also have the potential to [cause] significant economic losses and fatalities."
The federally funded analysis is among the first to use supercomputer simulations developed in the U.S., Japan, France and Russia for an international committee of scientists, the Intergovernmental Panel on Climate Change.
Since California frequently suffers droughts and floods and was gripped by a prolonged summer heat wave that caused more than 100 deaths and triggered power outages, many state officials are alarmed by the dire predictions, which echo other scientists' warnings.
"The signs of climate change are all around us, but the impacts can be dramatically lessened if we take action now to reduce greenhouse gas emissions," said Linda Adams, California's secretary for Environmental Protection.
The scenarios were based on three projections in volumes of greenhouse gas emissions, which come largely from the burning of gasoline, coal and other fossil fuels.
