“Projected changes in precipitation, coupled with rising extreme temperatures before mid-century, will reduce Midwest agricultural productivity to levels of the 1980s without major technological advances,” according to the Fourth National Climate Change Assessment.
Most media reports on the Fourth National Climate Change Assessment present the big picture for the future of the United States under a changing climate. In fact, it seems most reporters didn’t get past the Assessment’s Executive Summary.
April Baumgarten, a reporter for the Grand Forks Herald and the Forum News Service, seems to have been somewhat of an exception. The report is made up of 1,600 pages with 29 chapters. Ten of them focus on various regions of the U.S. Baumgarten studied the section on the Northern Great Plains for her December 16th article.
For purpose of the Climate Assessment, the Northern Great Plains’ eastern boundary is the Red River. So, seeking to add to Baumgarten’s study of the Assessment’s chapter on the Northern Great Plains, I studied the chapter on the Midwest with a focus on the section on agriculture.
The Midwest chapter also includes sections on Forestry, the Great Lakes, Transportation and Infrastructure, and others.
“By conservative estimates, the days that are projected to be above 90 degrees in North Dakota by the mid-21st century likely will increase by 10 to 25 days,” Baumgarten wrote.
Minnesota, and the Midwest, haven’t been getting warmer but we have been getting less cold, according to the Assessment. Those of us who farm have noticed that over the years the date of the last spring frost has consistently been pushed further into what was once winter-like weather. The Assessment bears out our anecdotal experience.
“The last spring frost has occurred earlier, causing the frost-free season to increase by an average of nine days since 1901. However, daily maximum temperatures in summer in the Midwest have not followed the upward global trend, in part due to higher early summer rainfall on deep, water-holding soils, thereby avoiding plant stress detrimental to crops.”
Essentially, we’ve been having milder and shorter winters. Those milder winters have created an environment where certain pests and diseases have been able to thrive, according to research published in the scientific journals Global Change Biology and Nature Climate Change.
The rising average daily minimum temperature has also had the surprising effect of playing a role in reducing grain quality.
“Elevated growing-season minimum daily temperatures are considered a factor in reducing grain weight in corn due to increased night time plant respiration,” according to the Assessment.
But, in the future, the Midwest will not only be less cold but our region will start to catch up in the daily maximum temperatures department.
“Current average annual 5-day maximum temperature values range from about 88°F in Northern Minnesota to 97°F in Southern Missouri,” according to the Assessment. “5-day maximum temperatures are projected to have moved further above optimum conditions for many crops and closer to the reproductive failure temperature, especially for corn in the southern half of the Midwest. Higher growing-season temperatures also shorten phenological stages in crops (for example, the grain fill period for corn). Under these temperatures, overall yield trends will be reduced because of periodic pollination failures and reduced grain fill during other years.” (The following tables, from the Assessment, demonstrate what happens to crops when it gets too hot.)
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“Current average annual 5-day maximum temperature values range from about 88°F in Northern Minnesota to 97°F in Southern Missouri,” according to the Assessment. “5-day maximum temperatures are projected to have moved further above optimum conditions for many crops and closer to the reproductive failure temperature, especially for corn in the southern half of the Midwest. Higher growing-season temperatures also shorten phenological stages in crops (for example, the grain fill period for corn). Under these temperatures, overall yield trends will be reduced because of periodic pollination failures and reduced grain fill during other years.” (The following tables, from the Assessment, demonstrate what happens to crops when it gets too hot.)
Table 21.1: Average Annual 5-Day Maximum Temperature
Table 21.1: These modeled historical and projected average annual 5-day maximum temperatures illustrate the temperature increases projected for the middle of this century across the Midwest.
Table 21.2: Optimum and Failure Temperatures for Vegetative Growth and Reproduction
Table 21.2: This table shows the temperatures at which corn and soybeans reach optimum growth and reproduction as well as the temperatures at which growth and reproduction fail
Baumgarten’s Grand Forks Herald article pointed out that climate change will have effects on other aspects of life in the Midwest and Great Plains. Ironically, she points out the oil production in North Dakota will become more expensive because of the growing scarcity of water.
“Finally, higher maximum temperatures, longer and more severe heat waves, and higher overnight lows are expected to increase electricity demand for cooling in the summer, further stressing the power grid,” she wrote.
You can read Baumgartens article here
The Fourth National Climate Change Assessment is here
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