It is late June in east-central Iowa, but it feels more like August. Temperatures run into the 90s, with heat indices over 100. High humidity soaks everything. Flood warnings speckle weather maps: Swathes of Iowa received 8 to 10-plus inches of rain in recent weeks, about one-fourth of a normal 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 — the greatest increase occurring since 1980. Virtually all trained scientists agree 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 have recorded an increase of 2 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 the increase has occurred since 2000, and (like humidity) higher rainfall is concentrated in the spring months of April, May and June.
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Heat is a form of energy. So, 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, which was the highest annual such expense on record.
Since 1980, damages from increasingly frequent extreme-weather events have exceeded $1.5 trillion. Add other factors to economic stresses — climate-related health problems, agricultural upsets, infrastructure failures, 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. By 2100, if we continue with business as usual, our global average temperature is predicted to rise between 7 and 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 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.
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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, 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, with IIHR-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 the 2010 “Climate Change Impacts on Iowa” report prepared for the Iowa Legislature and governor.