While the drought of 2012 departed dramatically from the recent pattern of increasingly wet years in Iowa, it is consistent with overall climate change, according to state officials and scientists.
The drought does not suggest a reversal of that wetness pattern but rather a continuation of the trend toward more extreme weather, said Iowa State University professor Eugene Takle, director of ISU’s Climate Science Initiative.
“It is not unreasonable to expect we will have more of these extreme climatic conditions — both dry and wet,” Takle said.
Takle’s ISU colleague, Climate Science Initiative Assistant Director Christopher Anderson, said the drought of 2012 contrasts with the increasingly frequent heavy rainfall days and wet springs that have prevailed in Iowa since 1990.
Unlike the drought in the southwestern United States, which “does appear to be related to climate warming,” the 2012 grain belt drought “looks very similar to past droughts” — most notably the memorable droughts of 1936, the mid 1950s, 1983 and 1988, Anderson said.
“Nevertheless, the combination of climate warming and cyclic phenomena suggest it is very likely that in the 2020s this type of drought will become more likely than it is today and has been in the past,” Anderson said.
Takle said Iowa droughts don’t fit the definition of cyclical. “They are recurrent but not on a predictable cycle,” he said.
Takle noted that Iowa is vulnerable to shifts in precipitation because it sits on a moisture gradient with dryer regions to the north and west and wetter regions to the south and east.
A shift in either direction could alter the state’s favorable grain production climate, he said.
More water vapor
Because Iowa consistently has more water vapor in the air than it had several decades ago, Takle said his “gut feeling is that floods will be more frequent in Iowa than droughts.”
Takle said he believes that outlook is shared by most Iowa farmers, who would, he said, be much more likely to invest in drainage tile than in irrigation systems.
“This is what climate change looks like: more droughts, more floods, more disasters. It’s not what we have been accustomed to, but we had better get prepared for it,” said state Sen. Rob Hogg, D-Cedar Rapids.
Hogg said climate predictability has been lost. “As recently as 25 years ago, weather disasters were widely spaced. Now it is almost serial disasters,” he said.
Hogg said he believes human behavior — primarily the burning of fossil fuels — is responsible for the world’s changing climate.
“We can achieve dramatic decreases in greenhouse gas emissions” by relying more on solar and wind energy and increasing the energy efficiency of buildings and vehicles, Hogg said.
More carbon dioxide
Human influence, though not quantified, definitely affects weather and climate, according to ISU climatologist Elwynn Taylor.
Carbon dioxide in the earth’s atmosphere has increased from 312 parts per million in the 1950s to 385 ppm now, mostly because of the burning of fossil fuels, Taylor said.
“The solution is simple if not necessarily palatable,” Taylor said.
While people may debate causes, most Iowans recognize that their climate is changing, said Joe Wilkinson, president of the Iowa Wildlife Federation.
The drought of 2012, which may not be over, was “just another eye opener,” following extreme Iowa floods in three of the four preceding years, Wilkinson said.
On wet side
State Climatologist Harry Hillaker, who takes no position of the causes of climate change, said weather data show that Iowa, until this year, has been “very much on the wet side since the late 1950s.
Through the first eight months, 2012 has been Iowa’s hottest year so far, at 5.83 degrees above normal, according to Hillaker. It would have to stay 4 degrees above normal for the rest of the year to top the record holder, 1931, he said.
The June-August meteorological summer this year has been the fifth driest and 14th hottest on record — quite similar to the state’s last memorable drought, in 1988, when the June-August period was fourth hottest and 14th driest on record, Hillaker said.
Takle said the 2012 drought “unmasked the warming of Iowa’s climate.” The warming, he said had been observed in winter temperatures and summer nighttime temperatures but not in summer daytime highs.
The excess rainfall that had been prevalent in recent years had moderated summer daytime highs, according to Takle.
Without that moisture this year, those highs soared often into the upper 90s and low 100s and contributed greatly to 2012’s status as one of the hottest years on record in Iowa, Takle said.