What’s climate change doing in Iowa?
Late June in east-central Iowa felt more like August. Temperatures ran into the 90s with heat indices over 100. The high humidity soaks everything. Flood warnings speckle weather maps: Swaths of Iowa received 8 to 10-plus inches of rain in recent weeks, about one-fourth of the normal Iowa yearly average. In places, intense storms have dumped nearly that much rain in a few hours. The oppressive weather feels relentless.
Are these normal weather variations, or might the climate be changing? What happened to June’s enticingly crisp, clear, comfortable days? By examining long-term statistics, we can begin to answer these questions.
Between 1901 and 2016, Iowa’s annual average temperature rose about 1 degree Fahrenheit, half the global average rise of 1.8 degrees (1 degree Celcius), with the greatest increase occurring since 1980. Virtually all trained scientists agree that this warming is caused primarily by the release of carbon dioxide and other greenhouse gases from the burning of fossil fuels. And that today’s small average temperature rise is already affecting weather events around the globe. Most of Iowa’s warming is occurring during winter and at night, mercifully excluding more extreme summertime highs, at least for now.
One degree average rise. Not much, but the implications are profound. Higher temperatures naturally increase water’s evaporation from lakes, rivers and soils. And warmer skies can hold more moisture than cooler skies.
Thus Iowans might expect increases in atmospheric humidity, and we are getting them. Monitoring stations across the state have recorded an increase of 2 percent to 4 percent in absolute humidity per decade since 1971, with the greatest rises in the eastern half of Iowa. Increases are largest in the springtime months of April, May and June. During these months, between 1970 and 2017, Dubuque measured an amazing 23 percent increase in absolute humidity.
More humidity, more rain. Iowa's annual precipitation has gone up about 5 inches, from a statewide average of 31 or 32 inches at the beginning of the 20th century to around 36 inches today. Most of that increase has occurred since 2000, and (like humidity) higher rainfall is concentrated in the spring months of April, May and June.
Heat is a form of energy. Thus our hotter, moister skies are producing more intense extreme weather events. In the Upper Midwest, very heavy precipitation increased 37 percent between 1958 and 2012. Today’s intense gushes of rain increase erosion of soil, pesticides, and fertilizers.
Intense rains and other extreme weather events are expensive. Nationally, extreme weather events cost $306.2 billion in 2017, the highest annual such expense on record. Since 1980, damages from increasingly frequent extreme-weather events in the U.S. have exceeded $1.5 trillion. Add other factors to economic stresses — such as climate-related health problems, agricultural upsets, infrastructure failures, and effects on nature — and it’s clear that climate change touches everything.
More humidity and heat, bearing down on us with increasing intensity. These are the signatures of Midwestern climate change. In addition, our weather is becoming less predictable, less dependable. This year June’s heat and rain followed the coldest April on record, and one of the warmest Mays.
What if we fail to rapidly and dramatically address climate change? Predictions state that by 2050, Iowa’s greatest summertime once-per-decade heat waves will be 13 degrees hotter than today’s. By 2100, if we continue with business as usual, our global average temperature is predicted to rise 7 to 9 degrees, making the effects of today’s world-average 1.8-degree rise seem like child’s play.
What can we do to prevent this? Let’s start by recognizing that the science of climate change is accepted by virtually all trained climate scientists. Then let’s act accordingly on all levels, focusing on speeding the switch to renewable energy sources that can power our world without multiplying climate change. This means changes in policies and regulations — just as other nations are invoking.
China, now the poster child for manufacturing and installing solar arrays, is working toward banning the manufacture and sale of fossil fuel cars, as are Britain and Norway. Costa Rica was almost totally powered by renewable energy in 2017, and New Zealand has committed to carbon neutrality by 2021, with other nations joining the lineup. Here in America, we need to talk about climate change more, vote accordingly, advocate strongly, and praise the businesses, state and local governments, churches, and other entities that are lowering their greenhouse gas emissions. And each of us needs to consider the greenhouse-gas emissions and climate impacts of our own choices — our cars, diet, home size and energy efficiency, our consumption patterns.
We are now in a race between rising fossil fuel emissions and efforts to reduce these emissions and moderate their spinoffs. The switch to renewable energy is happening, even as global temperatures continue to rise. The benefits of renewables are many: cleaner air and water, improved human and environmental health, economic stimulation and more jobs (8,000 to 9,000 in Iowa’s wind energy alone), a better-functioning and more intact natural world.
Which forces will win the race? We don’t know. But we do know this: All people on the planet at this crucial time will own the results. Will we continue to allow current trends to slide us toward a less dependable globe that degrades life’s abundance, beauty, and health? Or will we work for a self-renewing, healthier, more stable planet fueled by the sun, wind, and other renewables? The choice remains ours.
Connie Mutel of Solon, who works with Iowa Institute of Hydraulic Research-Hydroscience and Engineering at the University of Iowa, is author of several books on nature in Iowa, including "A Sugar Creek Chronicle: Observing Climate Change from a Midwestern Woodland," and editor of "Climate Change Impacts on Iowa."