Gene Takle, Professor, Iowa State University: Iowa's climate is very interesting and somewhat unique because we're positioned in the middle of the continent but that we have water to our south in the form of the Gulf of Mexico and this has a profound effect that keeps us from being like many other Mid-continent regions that are really quite dry. So we have a source of moisture, particularly in the summertime—our growing season, which means that we have this very favorable condition for growing crops in our state.

What is climate? Climate is what we expect based on records and data of weather conditions over several years or decades. Weather is what we get in the short term. When measurements like temperature, precipitation, wind and humidity vary significantly for an extended period, that's what we call climate change. And the data shows climate change is happening in Iowa.

Takle: Something in our climate has changed from what it was. Grandpa didn't have to deal with these issues back on the farm then, they didn't see these soggy soils all during the spring, they didn't have this humidity, they didn't have mold in the basement back in there, and he didn't have air conditioning. Now, I have air conditioning in my house and I still have mold in the basement. What's different? Something's different.

One of the most notable changes in Iowa's climate is increased frequency and intensity of heavy precipitation events. We're seeing more flooding. The state's average annual rainfall has gradually increased, but between the 1870s and 1950 Iowa had just two years with more than 40 inches of rainfall for the year. From 1950 to the early part of this century, it happened eight times. We also have much higher humidity levels that fuels convective thunderstorms that provide even more precipitation.

Takle: It's like getting a bigger can of gasoline to throw on the fire, so to speak, and that's what's happening, that there's more of the ingredients that drive these large rain events and six and seven inches, which in the first half of the 20th century these were really very rare events. Now we're not amazed anymore by hearing these because we have the ingredients that are favorable to those kind of different extreme events developing.

We've experienced warmer average winter temperatures and cooler summer temperatures in recent years. That's expected to change in the next couple decades.

Takle: The maximum daily temperatures in summer have actually gone down. We have fewer days above 100 degrees than we had 50 years ago and that's because of this additional rainfall that we have that is suppressing the warming because of all the water on the surface that the Sun is evaporating. So instead of heating the air it's using that energy to evaporate water. So as a result our air temperatures haven't increased. Our humidity has gone up a lot, but our air temperatures haven't risen but that's going to be a change in the future. It's going to be the warming, we will experience that more in the mid to later half of the 21st century.

The current average five-day maximum temperature during a heatwave is 93 degrees. Projections for the year 2050 would raise that seven degrees to 100, and once a decade we could expect a heatwave with a high of 106 degrees. That kind of heat has wide-ranging impacts. Even summer nighttime temperatures will be on the rise.

Takle: And after a while we have to think about how vulnerable are these natural processes to what we really cherish in our state and what drives our economy. So that's where we're starting to learn more about these natural services and how they might be impacted by climate change.

Increased precipitation and temperature changes present challenges for Iowa agriculture. Much of the heavy rains have tended to come during the spring planting season and early summer, forcing farmers to adapt. For example, some use tracks instead of tires on their tractors to better handle wet ground, and they're buying bigger planters and combine heads to get the crop planted and harvested in a shorter time frame. Soil erosion and runoff effect topsoil conditions and water quality in Iowa lakes and rivers. Unwanted pests and diseases may move in.

Takle: We've had some very favorable climate and looking forward we can't be assured that that's going to continue. In fact we see reversals of some of this. I would think that we're going to be challenged to maintain the kind of reliable production that we've had over the past 60 years.

Climate change means plants and trees are flowering and leafing out sooner. Bird migration patterns are different. Animal habitats are changing, and Iowa's game wildlife populations could drop. Finally, Iowans’ health could suffer negative consequences from climate change. Mold from higher humidity and increased air pollutants can trigger asthma and allergy problems. Infectious diseases may spread more easily. And dangerous heat waves can lead to illness or death.

Takle: We've got good records of sunspots and their impact on the climate. Our release of greenhouse gases are now far larger than the impact of the fluctuations in the output of the Sun. There is no physical way that we can return to the 20th century average global temperature within the next 20 or 30 years. Even if we if we reduce all our use of fossil fuels today, we will not return to the 20th century average climate.

There's no going back but it's not all doom and gloom. Iowans can help reduce impacts of climate change by improving infrastructure to deal with the changes, and by taking advantage of opportunities to harness wind and solar energy.

Takle: How we manage our landscapes, how we manage our cities, how we build our buildings, our energy use, these are all ways that we can participate in the mitigation side and reducing the impact.

Climate change is real, it's already here, and conversations among Iowans, including elected leaders, will help identify what we and should do about it.


Gilchrist Foundation