2019 was Iowa’s 12th wettest year on record, with an average of 41.49 inches of rainfall across the state, according to the state Department of Natural Resources. Rainfall in May, September and October was especially high, while the summer months experienced below average rainfall.
The two-year 2018/2019 period was the wettest on record, with 19 more inches of precipitation than average. Stream flows were above normal all 2019 following heavy snow in the winter months. The rainy spring and fall seasons are indicative of projected climate change models for the region.
2019 temperatures in Iowa were cooler than average, however, by 1.2 degrees Fahrenheit. During the January “Polar Vortex,”one station in Emmet County recorded a -59 degree windchill. Summer was slightly cooler than average, though July and September were warm, andChristmas week broke record temperature highs.
Iowans across the state experienced severe flooding this year, and according to a report released Thursday by the Iowa Policy Project, flooding events like those of 2019 will likely become more frequent and severe as the climate changes. While temperatures and precipitation have been shown to be rising, flooding patterns are harder to predict, but this year’s “100-year flood” seems to be the fourth flooding event of its kind in only 30 years, following severe floods in 1993, 2008, and 2011.
Both the Mississippi and Missouri River Basins flooded this year, with the Mississippi breaching a levee in Davenport, and the Missouri breaching every levee south of Council Bluffs on the western side of the state. In addition to the damage caused to flooded roads, homes, and businesses, these floods have harmed agriculture. Farmers were forced by flooded fields to plant late or not at all this year. The floods spoiled stored crops, caused the deaths of livestock, and damaged farm infrastructure. Flooding and extreme heat also pose a threat to human health through contaminated water supplies, the spread of disease-carrying insects, and harm to mental health.
The period from May 2018 to April 2019 set new records for precipitation in the Midwest, with Iowa exceeding the regional average with over 50 inches. Since the 1970s, Iowa’s average annual rainfall has been rising by 1.25 inches per decade – the highest rate of any state in the country – and snowfall this February reached three and a half times the recent average. Springtime rainfall in the upper Mississippi is projected to increase 20 to 40 percent. The report also covered temperature increases, which are projected to be the highest in the Midwest during the warm season.
The study analyzed U.S. Department of Agriculture data from more than 800 counties across North Dakota, South Dakota, Wyoming, Nebraska, Iowa, Colorado, Kansas, Oklahoma and Texas from 1968 through 2013. Collectively, they found that climate change caused about 25 percent of crop yield variance during that time. While temperature and precipitation changes were responsibile for 52 percent of crop fluctuations in some counties, they did not have any effect in others.
Similarly, the three crops that were studied: corn, soy and sorghum, all responded to the changing climate differently. Corn is more likely than the other two to be impacted by rising temperatures. When corn plants are not irrigated, yields are twice as likely to be harmed by increased temperatures. However, irrigated corn seemed to do relatively well in these conditions. Irrigated soy and sorghum plants were much less likely than non-irrigated plants to be negatively impacted by precipitation and temperature shifts too.
Suat Irmak and Meetpal Kukal are the study’s authors. They say that their work makes the case for continued climate change studies which consider different climate variables, crop types and growing conditions.
“I hope we are successful in getting across the message that there are changes in temperature and precipitation, (but) those changes are different over time and location, and they are having different impacts on our agricultural productivity,” Dr. Irmak said to the University of Nebraska. “That can help high-level advisers, decision-makers and policymakers to identify locations where those impacts are greatest so that resource allocation or re-allocation can make (fields) even more productive.”
During the second half of the 20th century, corn production in the midwest increased by 400 percent and soybean yields doubled due to more intensive agricultural practices. The study, which was published in Geophysical Research Letters, found that the midwest also saw significantly more precipitation and lower temperatures during the summer months over the same period of time. They concluded that the changes were not merely correlated, but that the land use change actually caused the regional climate changes.
The authors explain that each time plants take in carbon dioxide, they release moisture into the atmosphere through pore-like structures called stoma. With more plentiful and robust plants due to intensive agriculture, the amount of moisture corn and soy crops collectively release into the atmosphere has increased in the midwest since the 1950’s. This extra moisture, the study found, has caused summer air to cool and more precipitation to fall. In the last fifty years, average summertime rainfall in the midwest has increased by 15 percent and average summer temperatures have dropped by 0.5 degrees Celsius.
Roger Pielke Sr., a senior researcher at the University of Colorado at Boulder commented on the study, he said, “This is a really important, excellent study. The leadership of the climate science community has not yet accepted that human land management is at least as important on regional and local climate as the addition of carbon dioxide and other greenhouse gases into the atmosphere by human activities.”
Since completing the study, the researchers have developed a formula that accounts for the causative relationship between plants and regional climate changes that can be entered into U.S. regional climate models. It correctly predicted those changes that have been observed in the midwest over the last 50 years.
The study opens the door for further research into land use changes and how they can affect local climate.
Rainfall in the last part of August helped to lift many parts of Iowa out of drought conditions, but some parts of the state are still experiencing extreme drought, according to the latest Water Summary Update.
The Water Summary Update is a succinct monthly report of Iowa’s water resources and those events that affect them prepared by the technical staff at Iowa DNR, the Iowa Department of Agriculture and Land Stewardship, IIHR—Hydroscience and Engineering, and the U.S. Geological Survey, in partnership with Iowa Homeland Security and Emergency Management Department.
The latest summary revealed that while August started off very dry, high rain totals increased groundwater levels and streamflow in many parts of the state. The total area of the state classified as experiencing drought or dryness decreased from over 70 percent at the beginning of the month to 55 percent this week. In contrast, south central Iowa is still experiencing D2 and D3 drought conditions. Clarke county and Wapello county are seeing the most extreme dryness.
Researchers point out that August temperatures this year have been about three to four degrees cooler than normal, on average. Lower temperatures slow down evaporation rates and provide a protective factor for crops in drought-stricken areas.
To follow Iowa DNR’s regular water summary update, visit their website here.
According to the Union of Concerned Scientists, wildfires have become more likely and more intense since the 1980’s. They last nearly five times as long, occur almost four times as often and burn more than six times the land area on average.
Moving forward, residents of fire-prone regions can expect the wildfire season to lengthen. In the southwestern U.S., scientists predict wildfire season will increase from seven months to twelve months.
The economic impacts of wildfires are staggering. Since 2000, the U.S. Forest Service has spent more than $1 billion on fire suppression in one fiscal year on two occasions. During the first decade of the 21st century, wildfires cost an average of $665 million per year in economic damages.
In their full report on this issue, the Union of Concerned Scientists say it’s not too late for humans to slow the course of climate change. They write,
“The global temperature is increasing and the climate is changing due to the greenhouse-gas emissions we have already produced, leading to a likely rise in the incidence of wildfires. But it is not too late. What we do now has the power to influence the frequency and severity of these fires and their effects on us.”
The first of its kind, a recent study found that climate change is likely to decrease the number of “nice weather” days worldwide.
The authors of the study, scientists from the National Oceanic and Atmospheric Association and Princeton University, define “nice” or “mild” days as those days when temperatures are between 64 and 86 degrees Fahrenheit, dew points are below 68 degrees Fahrenheit and less than half of an inch of rain falls. Currently there are an average of 74 nice days globally per year, but that number is likely to drop to 70 in the next twenty years and to 64 by 2081.
Karin van der Wiel is a postdoctoral researcher at Princeton University and lead author of the study. She said,
“We used a climate model to simulate the current climate. In that simulation we counted the number of mild days. Then, we increased greenhouse gases in the climate model to simulate the future effects of climate change. This leads to increasing temperatures, changes in humidity, changes in precipitation over the whole world and with very specific patterns. In this new, future climate, we counted the number of mild days again. We could then calculate the change — increase or decrease — of mild weather days for each location globally.”
Not all corners of the Earth will be affected equally, however. Tropical regions are expected to lose the most nice days, with some areas losing up to 50 per year by the end of this century. Meanwhile, London is expected to gain 24 nice days each year.
Predictions for Cedar Rapids, Iowa mirror global averages. Eastern Iowa currently enjoys 76 nice days annually; researchers say that number is expected to drop to an average of 72 between 2016 and 2035 and to 66 each year between 2081 through 2100.
Frequent high humidity makes it tough for Iowa to meet the pleasant weather criteria outlined in the study. Absolute humidity has risen by 13 percent during the summer months in Des Moines since 1970, according to Iowa State climate scientist Gene Takle. Increased humidity also contributes to the extreme rain events that have plagued Iowa in recent years.
van der Wiel said, “Mild weather is something everyone knows, experiences, and has memories of,” she continued, “Our study shows that human-caused climate change is going to lead to changes in mild weather all over… The changes are happening now, and where people live.”