“Any given year in the future could be above or below that rising trend,” Crouch said. “But if the current trend continues, the chances of years like this become greater.”
The Midwest is particularly vulnerable to large swings, according to federal scientists, in part because it is farther from the oceans, which help to moderate temperatures.
“There is a high degree of confidence in projections that future temperature increases will be greatest in the Arctic and in the middle of continents,” according to the U.S. Global Change Research Program.
Water, but not to drink
Maybe the broadest and most easily measured casualty of the weather has been the nation’s corn crop, one of its largest. With the losses, corn futures last week rose to all-time highs.
But the extreme weather has also aroused unusual challenges.
The Mississippi River has fallen so low that the American Queen steamboat, which had been on its way from Louisville to Vicksburg, Miss., had to stop this month in Memphis, according to wire reports. That left 240 passengers to finish the trip by bus.
In Plaquemines Parish, La., at the mouth of the Mississippi, government officials are preparing to have fresh water brought in on barges, something they haven’t had to do since 1988, during a historic drought, said Guy Laigast, director of the parish’s emergency preparedness. The problem is the growing salinity of the Mississippi as it runs by Plaquemines. Some saltwater seeps in from the gulf regularly when the river is low. But this year, the saltwater has seeped about 88 miles up the river, rendering it unusable for some towns.
In Kansas, along Big Creek, which is running dry, the drought has put communities at odds with one another. Upstream, Hays is keeping its wastewater to water a golf course, a park and a soccer complex. This has angered downstream neighbors, who say public wells are running low and there’s no water for their cattle.
“Everyone out here is hurting. There is no two ways around it,” said Doug Langhofer, water superintendent in Russell, Kan., one of the communities downstream.
Across the country, scientists are beginning to register the stress that higher temperatures have placed on the environment.
On the night of the fish kill that Pedretti reported on the Des Moines River, state biologist Mark Flammang was called to the scene.
“We’ve had fish kills before but never to that extent,” he said.
Often, he said, fish kills come when the oxygen content in the river goes low. But the measurements he took that night suggest to him instead that it was probably the unusually warm water.
Another fish kill in the Des Moines River happened just two weeks ago, and again the water temperature was high. This time, it was about 92 degrees in places, and it claimed about 13,500 fish, mostly river carpsuckers and channel catfish, he said.
Where those temperatures stand in terms of the river’s history is difficult to know because there are few, if any, consistent records. But Flammang and locals familiar with the river think those temperatures were well above normal summertime averages.
“The water normally has a chill to it,” said A.J. Bower, 26, who runs a local Web site for enthusiasts. But “the heat is killing the fish. You can tell it’s not supposed to be that warm.”
“Mother Nature,” he said, “is kicking our butt.”