Subject: ISU expert on global climate change

Global warming at the local level

by Barbara McManus,
Agriculture Communications
The forecast for 2040: More snow. More rain. More droughts. More
extremes. This winter may have been a harbinger -- Iowans shoveled
through near-record snowfalls, the fourth largest in 100 years. Gene
Takle, professor of agronomy and geological and atmospheric sciences,
believes such extremes may be the norm in the future due to global
warming.

"It's clear that 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 of change, it's alarming."

During the last two decades, an increase in global temperatures has
caught Takle's attention. Scientists predict that a doubling of carbon
dioxide levels in the atmosphere could increase the mean global
temperature from 3 to 10 degrees over the next century. Such temperature
increases could bring about extreme weather. Takle compares it to
placing a pan of water on the stove to boil.

"We've cranked up the heat, so things will happen faster and more
intensely," Takle said. "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 to be published this spring in the Journal of Geophysical
Research, Takle and three other Iowa State researchers looked at how
global warming would change weather and hydrology patterns in Iowa and
the rest of the upper Mississippi River basin, which includes portions
of Minnesota, Missouri, Illinois and Wisconsin.

"We used a climate model that would show the impact of global change on
a regional level," Takle said.

The modeling is similar to the concept used to forecast the weather for
the six o'clock news. While those forecasts predict temperature highs
and lows for a five-day period, Takle's climate model provides a broader
forecast for the future. To test the climate models, scientists input
historic data from past weather events and compare 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."

Takle 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, Lion's 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."

http://www.iastate.edu/Inside/04/0312/takle.shtml