The good, the bad and the climate change

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May 15, 2011 - 7:00pm

Climate change comes in many forms.

Farmers in parts of Africa are experiencing extreme, debilitating droughts, and regions such as Bangladesh are facing flooding and sea levels rising as much as three feet.

In the Midwest, though, farmers are actually seeing positives and negatives from warmer springs and more humid summers.

"Plant breeders attribute at least one bushel per acre per year yield increases to better, more favorable climate," said Gene Takle, a climatologist at Iowa State University.

This is not a surprise. NASA climate models in the 1990s predicted much of what has come to pass over the last decade, Takle said.

"The model showed winters and summers would have higher temps, winter temps would increase faster, that has occurred," he said. "Nighttime temps would increase faster than daytime temps, that also has been manifest. "

The result has been a longer growing season and more soil moisture.

But researchers say the changes also could bring more extreme and unpredictable - weather such as more intense rainstorms, especially in the spring.

This matters because frequent, more pounding rains will wash away precious soil and fertilizer that the crops need to grow, said Iowa State University soil scientist Matt Helmers.

"During spring of (the) year, there's not much crop canopy and soils can be susceptible," he said.

Many farmers till crops under in the fall, and this churns up the soil and leaves it exposed, without roots to hold it in place all winter.

But there's more. In the last 30 years, moisture in the air in Iowa and the region has increased by 13 percent, Takle said.

With more humid nights: "It means dew on crops comes earlier in evening, and lasts longer in morning, so that's more favorable conditions, pests, pathogens, molds, toxins and so on."

Gray leaf spot, white mold, sudden death syndrome, mycotoxin infestations, crazy top, common smut, stem rust, soybean mosaic virus ... Those are just a few of the crop diseases that have surged northward with warmer, wetter weather in the Midwest, according to report by NASA scientists.

And Iowa State entomologist Matt O'Neal said warm weather currents also could serve to transport the insects more effectively because of the way many insects find food and homes - by flying straight up.

"They get sucked into weather patterns... into the jet stream, and they use that to get far, far away, and then they literally get rained out of sky," O'Neal said.

Higher temperatures also allow some insects to overwinter and emerge earlier, when young plants are still vulnerable.

O'Neal is studying aphids. Infestations of these pen-point sized critters can literally suck the life out of crop plants.

"They're also flying dirty hypodermic needles, piercing sucking mouth parts, dirty needles that pick up virus from infected plant, travel to another plant and spread it," he said.

It doesn't sound good. But O'Neal said there are things farmers can do to limit pests and pathogens. He's working with scientists breeding aphid-resistant soybeans, and a plant pathologist who's trying to develop a sort of natural vaccine that could make plants resistant to the viruses.

"Farmers adapt to everything, new pests, markets, rising prices, they have just over years learned to adapt," O'Neal said. "Climate change is nothing new for them. "



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