Climate change affects crop yields in varying ways


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Soybeans are less sensitive to temperature and precipitation changes than corn plants. (Kevin Dooley/flickr)
Jenna Ladd | March 23, 2018

Researchers at the University of Nebraska recently published a study which details how climate change impacts crop yield variance on a hyper-local level.

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.”

The full study can be found in the journal Scientific Reports.

Crop production linked to regional changes in climate


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Corn and soy plants can cool the climate on a regional level, but intensified conventional agriculture can harm water and soil quality. (Lana/flickr)

Jenna Ladd | February 14, 2018

A new study by researchers at Massachusetts Institute of Technology and Dartmouth College detail the way intensive agriculture has influenced precipitation and temperature patterns in the midwest.

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.

August rainfall benefits some parts of Iowa


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August rainfall saved much of Iowa from severe drought conditions, but parts of south central are still experiencing extreme dryness. (Iowa DNR)
Jenna Ladd| August 25, 2017

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.

Wildfires become more common and intense as Earth warms up


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Smoke billows from the Lodgepole Complex wildfire of eastern Montana. (Montana Public Radio)
Jenna Ladd| July 26, 2017

A wildfire as large as New York City is currently ripping across eastern Montana, and experts say climate change making fires like these larger and more common.

As climate change takes hold, wet areas are becoming wetter and dry areas are becoming drier. Rising temperatures in spring and summer months mean that soils are remaining dry for longer, which makes drought more likely, thereby lengthening the wildfire season.

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.”

Climate change to decrease average number of mild weather days


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Residents enjoy pleasant weather at Noelridge Park in Cedar Rapids, Iowa. (Louis/flickr)
Jenna Ladd | January 24, 2017

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.”

Precipitation in Iowa falls below average for first time since June


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Streamflow remains above average for much of northeastern Iowa as the state heads into the driest season of the year. (Iowa DNR)
Jenna Ladd | November 8, 2016

The Iowa Department of Natural Resources (DNR) recently released its latest Water Summary Update. Each update provides an overview of the status of Iowa’s water resources using four categories: precipitation, streamflow, drought, and shallow groundwater. The latest update provides a water resource snapshot of trends from October 10 through November 3.

As Iowa heads into the driest season of the year, stretching from November through February, October was recorded as the first month since June in which rainfall fell below normal levels. “Abnormally dry,” or drought conditions persisted for south-central Iowa, with the lowest reported October rainfall of 0.54 inches recorded in Story County. Areas of north central and northeastern Iowa, which had experienced heavy rainfall throughout much of September, saw drier conditions at last.

Temperatures throughout the month of October were warmer than they have been since 2007, averaging about 4.5 degrees above normal. This season’s first freeze is yet to occur for the Des Moines metro area, as well as far eastern and southeastern Iowa. The northwest two-thirds portion of the state experienced its first deep freeze on October 13.

Since the previous Water Summary Update, streamflow in the Chartion River Basin in south central Iowa has decreased to normal levels. However, streamflow for most of Iowa remains above average. More specifically, streamflow in the Cedar, Des Moines, and Upper Iowa River basins remain far above average. The forthcoming four months not only mark the driest season of the year, but also the most hydrologically stable. During this period of time Iowa usually receives about 15 percent of the year’s total rainfall, or 5.5 inches of precipitation. In contrast, summer months in the state bring more than 18 inches of precipitation on average.

Water Summary Updates are released every two weeks or as water resource conditions in Iowa significantly change. They are prepared by the Iowa DNR in partnership with Iowa Department of Agriculture and Land Stewardship, the U.S. Geological Survey, and The Iowa Homeland Security and Emergency Management Division. A complete record of Iowa Water Summary Updates can be found here.

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(Iowa DNR)

2016 ranks third wettest ‘water year’ since 1872


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Each bi-weekly Water Summary Update provides the current status of water resources in Iowa in terms of precipitation, stream flow, shallow groundwater, and drought monitoring. (Iowa DNR)
Jenna Ladd | October 14, 2016

Iowa Department of Natural Resources (DNR) released its most current Water Summary Update earlier this week.

DNR prepares the bi-weekly updates in collaboration with the Iowa Department of Agriculture and Land Stewardship, the U.S. Geological Survey, and The Iowa Homeland Security and Emergency Management Division. Each report provides an overview of the status of Iowa’s water resources and significant events that affect water supplies using four categories: precipitation, stream flow, shallow groundwater, and drought monitoring.

The most recent update is a snapshot of the state’s water resources from August 31st through October 10th. The report notes that different parts of Iowa experienced a wide range of rainfall totals. Heavy rains pelted the Cedar River watershed during much of September, with the largest storm-total rainfall of 10.56 inches near Nora Springs in Floyd County. In contrast, some parts of southeastern Iowa experienced a particularly dry September. Most notably, rain totals were less than one-third of the average near Fairfield and Ottumwa. Average statewide rainfall was 6.29 inches or 2.91 inches above average, making it the rainiest September since 1986.

Streamflow was also reported to be above average for much of the state. The update notes that U.S. Geological Survey employees have been taking additional streamflow measurements following heavy rain events at the end of September in the Cedar and Wapsipinicon River basins. In several locations along the Shell Rock, Cedar, and Wapsipinicon Rivers, peak stream flow was found to be the second-highest in recorded history. These values are only topped by the historic 2008 flood.

October 1st through September 30th is considered the “water year” by experts in the field. The 2016 Water Year, which ended on September 30th, 2016, is the third wettest year on record in 144 years.