Dakota Farmer, OR
08-08-07
How Will Global Warming Affect U.S. Corn Belt?
Compiled By Staff
Iowa State University weather expert Gene Takle begins his talks about
climate change with some strong statements. "There is no question now that the
climate is changing on a global scale," says Takle, a professor of geological and
atmospheric sciences and agronomy. "The evidence is so overwhelming."
But what does that mean on a smaller scale? How are greenhouse gases
changing the climate in North America? In the United States? In Iowa? After all,
"You and I are not affected by a few tenths of a degree of temperature change on
a global scale," says Takle.
Takle is working with Bill Gutowski, an ISU professor of geology and
atmospheric science, and Ray Arritt, ISU professor of agronomy, to find
answers about regional climate change. The three have worked together on
climate studies for 15 years. Now they've joined an international group of
scientists collaborating on the North American Regional Climate Change
Assessment Program. That program is led by Linda Mearns, scientist at the
National Center for Atmospheric Research in Boulder, Colo. The National
Science Foundation is funding the ISU work on the project with a $353,000 grant.
The project calls for six teams of researchers (four from the U.S., including the
ISU group, one from Canada and one from Europe) to run their own regional
climate models using at least two sets of identical data from two research groups
studying global climate change. The research groups will see what their models
say about regional climate change and compare the results. Ultimately, the
researchers will create data sets that will help them study the impacts of climate
change on a continental or even statewide scale.
Weather has changed since 1975
Takle says the ISU research team has looked at Iowa climate data from 1975 to
2000 and observed some trends:
* Annual precipitation has increased by about an inch over the past 30 years.
More of that precipitation is happening in extreme weather events. In other
words, there are more 3-inch rains than there were 30 years ago.
* Winter low temperatures aren't as cold. That means there are about eight
more frost-free days than there were in the 1950s, making for a longer growing
season.
* Summer heat isn't as intense as it was 30 years ago, but the humidity is
rising. If those trends continue, climate change in the American Midwest could be
good for agriculture over the next 10 to 20 years. But researchers are looking for
more answers as they develop their regional climate models.
Looking ahead to year 2040 and beyond
The research teams started working on the climate change assessment program
about 18 months ago. The first task was to develop methods to manage and
share data.
The research groups have moved on to testing their models by running them with
climate data from 1979 to 2004 and comparing the results to what actually
happened. The models represent conditions in the middle of the atmosphere very
well, but have a harder time showing the distribution of summer rains.
The research groups are now preparing to use data from global climate models
to run climate simulations for the years 2040 to 2070.
Be prepared for even more changes in climate
Arritt says the results of those simulations will give researchers a good idea
about the range of possibilities for climate change across North America. He also
says it's a tremendous boost for researchers to work with six different climate
models and multiple sets of data. "As you know, no simulation or forecast is
perfect," he said. "By running a lot of different simulations we can see how wide
the window is."
Then researchers can look at averaging the results to get a more reliable
forecast of what kind of climate North Americans can expect by mid-century,
Arritt says. The models could have something to say about Iowa's weather, too.
The ISU team is working with a model that has grid points every 30 miles. That
works out to about one point per Iowa county. "That should provide a pretty good
picture of the state's future climate," says Takle. "And that's valuable information
for all of us. If the climate is changing, you can't stop it over the next 50 years.
What's coming is coming and we better be prepared to adjust to it."