Key messages

Six key messages from the draft National Climate Assessment Report regarding the likely effects of climate change on the Midwest:

1. In the next few decades, longer growing seasons and rising carbon dioxide levels will increase yields of some crops, though those benefits will be increasingly offset by the occurrence of extreme events such as heat waves, droughts and floods. In the long term, combined stresses associated with climate change are expected to decrease agricultural productivity, especially without significant advances in genetic and agronomic technology.

2. The composition of the region’s forests is expected to change as rising temperatures drive habitats for many tree species northward. The region’s role as a net absorber of carbon is at risk from disruptions to forest ecosystems, in part due to climate change.

3. Increased heat wave intensity and frequency, degraded air quality and reduced water quality will increase public health risks.

4. The Midwest has a highly energy-intensive economy with per capita emissions of greenhouse gases more than 20 percent higher than the national average. The region also has a large potential to reduce emissions that cause climate change.

5. Extreme rainfall events and flooding have increased during the past century, and these trends are expected to continue, causing erosion, declining water quality and negative impacts on transportation, agriculture, human health and infrastructure.

6. Climate change will exacerbate a range of risks to the Great Lakes region, including changes in the range and distribution of important commercial and recreational fish species, increased invasive species, declining beach health and harmful blooms of algae. Declines in ice cover will continue to lengthen the commercial navigation season.

Read the report

A draft of the National Climate Assessment Report is available for public comment at http://ncadac.globalchange.gov. Indiana University atmospheric science professor Sara Pryor is lead author of the chapter on climate change’s expected effects on the Midwest.

The entire report is 1,100 pages; Chapter 18, “The Midwest,” is 38 pages and can be downloaded separately.
If the average annual temperature of the Midwest rises by 4 degrees by 2050, what will happen to corn, soybean and other crops and to forests? Will climate change bring more droughts or more flooding? Will the power grid be able to handle increased demand for air conditioning?

Indiana University atmospheric science professor Sara Pryor has attempted to address some of those questions in her new book, “Climate Change in the Midwest: Impacts, Risks, Vulnerability and Adaptation,” published last month by IU Press.

She is also one of 60 members of the National Climate Assessment Development Advisory Committee, which has released a draft of the National Climate Assessment Report.

Pryor is a “convening lead author” for the chapter on the Midwest, making her a world authority on the projected impacts of climate change in the region.

The report intends to spell out the science and knowledge about climate change, to inform policy regarding how the effects can be lessened and how society can prepare to adapt to a very different environment, Pryor said in a recent interview.

“The rate of change of warming in the Midwest is alarming,” Pryor said. “It has warmed three times as quickly in the past three decades as it did in the century as a whole.”

Relative to 1970 to 2000 average temperatures, projections show the Midwest will warm by 3.8 to 4.9 degrees Fahrenheit by the middle of the century, and by 5.6 to 8.9 degrees by 2100, she said.
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