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Hope you don't see another blizzard-filled winter or hot, mosquito-laden summer for awhile? Don't hold your breath, warns an Iowa State University expert on atmospheric science and agricultural meteorology.

Gene Takle, ISU professor and certified consulting meteorologist, predicts that the continuing increases in global temperatures will result in more extreme weather conditions 30 to 40 years down the road.

"It's clear the planet is warming, and it's warming at an unprecedented rate," Takle said. "Something as big as this planet changes very slowly, so when we see changes that are large and abrupt in comparison to a normal scale, it's alarming."

How alarming? Thanks to increased carbon dioxide levels in the atmosphere, scientists predict mean global temperatures could increase 3 to 10 degrees over the next century. These temperature increases could cause noticeable weather changes, "like placing a pan of water on the stove to boil," Takle said.

"We've cranked up the heat, so things will happen faster and more intensely," he continued. "More precipitation and more heavy rainfall events mean more chances for flooding. There also may be more droughts and longer intervals between rain events. There may be two weeks between rains instead of one week, and that's pretty significant for agriculture."

In a study whose results will be published later this spring by the Journal of Geophysical Research, Takle and three other ISU researchers looked at how global warming would change weather and hydrology (the study of the waters of the earth) in Iowa and the rest of the upper Mississippi River basin, which includes portions of Minnesota, Missouri, Illinois and Wisconsin. The group used a climate model, not unlike that used by television meteorologists, to predict broader aspects of future weather conditions. To test the climate models, scientists have input historic data from past weather events and compared the results to the actual event.

When the regional climate model was combined with a soil and water assessment model (a tool that measures land-use impact on hydrology), the results for the upper Mississippi region indicated an 18 percent increase in snowfall, a 51 percent increase in surface water runoff and a 43 percent increase in groundwater by 2040. The changes would increase water runoff into the Mississippi River by 50 percent.

"That's pretty major," Takle said. "The most significant outcome of this model is that it projects a 21 percent increase in rainfall. That translates into a 50 percent increase in stream flow."

The ISU professor is confident there will be increases in precipitation, but he said it's difficult to predict how it will be distributed. Rainfall totals for any given year may be the same, but the rain may be dumped in shorter, more severe storms, which could result in flooding and erosion. Besides the impacts on agriculture and water resources, climate change could influence other segments of the basin, such as insect populations.

Takle said regional climate modeling helps scientists predict possible climate changes.

"Policymakers use economic models and demographic models to project how cities are going to grow and future needs," Takle said. "Why shouldn't we do the same with the climate?"

The sobering fact is that even if Americans quit driving and turned off the power plants today, the global temperature would continue to increase for another 50 years. Takle said excess carbon dioxide stays in the atmosphere for hundreds of years. Scientists have been considering the effects of scenarios that include a doubling of greenhouse gasses; now they are considering the results if greenhouse gasses triple.

"The reality is that we can't plant enough trees to take care of the amount of carbon dioxide we emit," Takle said.

He said he isn't a street-corner preacher on the topic. But if someone asks, he'll present his views because he's passionate about what is happening.

"I'm trying to raise the consciousness of the public. I talk to church groups, Lions clubs, the Kiwanis, school groups and utility companies," Takle said. "We need to get a dialogue going between climatologists and decision-makers. They need to understand this problem and start asking probing questions."