Models predict 'wild ride' of extreme weather

Longer heat waves, warm nights
What Tebaldi called the scariest results had to do with heat waves and warm nights. Everything about heat waves — their intensity, length and occurrence — worsens.

"The changes are very significant there," Tebaldi said. "It's enough to say we're in for a bad future."

The measurement of warm nights saw the biggest forecast changes in the study, which was described as a preview of a major international multiyear report on climate change that comes out early next year.

Every part of the globe is predicted to experience a tremendous increase in the number of nights during which the low temperature is extremely high. Those warm night temperatures that now should happen only once every decade by 2099 will likely occur at least every other year if not more frequently, Tebaldi said.

Warm nights are crucial because Chicago's 1995 heat wave demonstrated that after three straight hot nights, people start dying, Meehl said.

Adaptation strategy: air conditioning
However, heat wave deaths are decreasing in the United States because society has learned to adapt better by using air conditioning, noted University of Alabama at Huntsville atmospheric sciences professor John Christy. He is one of a minority of climate scientists who downplay the seriousness of global warming.

Similarly, the days when the temperature drops below freezing will plummet worldwide. That is not necessarily a good thing, because fewer frost days will likely bring dramatic change in wildlife, especially bug infestation, Tebaldi said.

"It's a disruption of the equilibrium that's been going for many centuries," Tebaldi said.

Christy, for his part, noted that a lengthier growing season in general is good.

"This notion of the greening of the planet ... generally is a positive benefit," Christy said.

Christy, who did not participate in the study but acknowledges that global warming is real and man-made, said an increase in nighttime low temperatures makes much more sense than the rain-and-drought forecasts of the paper.

One of the larger changes in precipitation predicted is in the intensity of rain and snowfall. That means, Tebaldi said, that "when it rains, it rains more" even if it doesn't rain as often.

The new study jibes with the National Climatic Data Center's tracking of extreme events in the United States, said David Easterling, chief of the center's scientific services.

Easterling's group has created a massive climate extreme index that measures the weather in America. Last year, the United States experienced the second most extreme year in 95 years; the worst year was in 1998.

Texas Tech University and Australia's Bureau of Meteorology Research Center also contributed to the new study.

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