A group of Iowa scientists say humidity levels are intensifying in Iowa and it’s a signal climate change is real.
The group’s “2017 Iowa Climate Statement” uses a familiar adage as its title: “It’s not just the heat, it’s the humidity.”
“Certainly it’s the combination of temperature and humidity that makes it feel so hot in Iowa in the summertime,” says Elizabeth A. Stone, a chemistry professor at the University of Iowa.
Stone and the other climate scientists report that humidity levels in the state have been rising significantly since 1971.
“Humidity is one of the meteorological variables that is continuously monitored at a number of locations around the state,” Stone says, “and so we went back and reanalyzed some of the data from the last about 45 years at eight longterm monitoring sites in Iowa.”
Humidity levels rose at all sites and during all four seasons.
“In particular, we found eight to 23 percent increases in absolute humidity across the state,” Stone says, “with the highest increases in humidity observed in eastern Iowa and lower increases in the west.”
Humidity is linked to the amount of water vapor in the air. The Iowa scientists say rising humidity levels are leading to increased flooding and increased demand for air conditioning and it translates into additional costs for Iowans.
“Humidity is certainly an intrinsic part of the water cycle and so higher humidity in the air does have a number of effects,” Stone says, “including increased rainfall, more waterlogged soils and it’s also associated with more extreme thunderstorm events.”
Stone is among 190 scientists from 39 colleges and universities in Iowa who signed onto this year’s Iowa Climate Statement.