Iowa’s signature summer humidity is not just an annoyance, it’s a costly reminder that climate change is real and needs to be addressed, a group of Iowa scientists said Wednesday.
Gene Takle, director of Iowa State University’s climate science program told a Statehouse news conference that “absolute humidity” measured by dew-point temperature has increased statewide by 8 percent to 23 percent since 1971.
Scientists have “good evidence” the rise is due to increased carbon dioxide in the atmosphere that likely will increase in the future, Takle said.
He is one of the architects of the seventh annual Iowa Climate Statement, released with endorsement of endorsement of 190 science faculty, researchers and educators from 39 Iowa colleges and universities.
Takle, a professor of geological and atmospheric sciences in the ISU Department of Agronomy, said the conditions relate to the increase of springtime moisture transported from the Gulf of Mexico that settle along eastern Iowa. That results in higher humidity readings measured across all seasons at all long-term monitoring stations in Iowa.
“The increasing cost for flooding, mold, insects, mosquitos, humidity-related health issues, grain drying, air conditioning, erosion, etc., are evidence that climate change in humidity already is having a negative impact on both public and private checkbooks,” Takle noted.
He said Iowa has been a national leader in embracing renewable energy sources but factors outside the state’s boundaries and control are negatively impacting the state’s climate.
"As long as we avoid making progress on reducing the atmospheric concentration of carbon dioxide, these effects are going to increase," Takle said.
The latest statement issued by the Iowa scientists describes the impact of significantly higher humidity levels on people, animals, crops and infrastructure.
According to the scientists, there is evidence:
• The frequency of intense rain has increased in Iowa over the past 50 years.
• There is a northward expansion of species formerly restricted by a colder climate that could disrupt natural ecosystems and introduce new agricultural pests and diseases.
• Agriculture, human health and economic stability could be affected if greenhouse gas emissions continue to increase.
“We must all do more to mitigate the effects of climate change, by curtailing emissions of heat‐trapping gases, improving energy efficiency, and increasing use of clean and renewable energy,” said Betsy Stone, a University of Iowa chemistry and biochemical engineering associate professor.
Stone pointed to monitoring data dating back to 1971 indicating average humidity increased by 8 percent in Mason City, 23 percent in Dubuque, 14.8 percent in Burlington, 11.9 percent in Des Moines, 10.7 percent in Waterloo and 9.2 percent in Sioux City.
“Increased levels of humidity create hazardous conditions for Iowa workers and sensitive populations through the danger of heat exhaustion and heatstroke. Asthma is worsened by higher levels of allergens in the air. And the cost of air conditioning homes and businesses to maintain comfort levels increases,” Takle said. “For Iowa’s agriculture, increased warm‐season humidity leads to water-logged soils during planting season, rising humidity also leads to longer dew periods and higher moisture conditions that elevate costs of drying grain. Increased nighttime temperatures coupled with humidity causes stress to crops, livestock and pets.”