This fourth post in our series delving into Global Climate Change Impacts in the United States, a landmark report issued June 16, highlights the climate change consequences we can expect to see in the Midwest. While this region will likely escape the prolonged droughts that are projected to plague the West and the Southeast, midwestern states will be exposed to the hazards of more frequent deadly heat waves, more frequent, heavier downpours, and disruption of freshwater lake ecosystems. Already there have been two record-breaking floods in the past 15 years: the Great Flood of 1993, and a record-breaking 24-hour rainstorm in July 1996, which resulted in flash flooding in Chicago and its suburbs, causing extensive damage and disruption.
CSW Series on Global Climate Change Impacts in the United States:
This fourth post of the series focuses on the Midwest; additional posts will look at Midwest, Great Plains, Southwest, Northwest, Alaska, Islands, and Coasts. The seven sectors addressed in the report are: Water Resources, Energy Supply and Use, Transportation, Agriculture, Ecosystems, Human Health, and Society.
See related posts:
Source: Global Climate Change Impacts in the United States. See the full, very-accessibly-written report for a more extensive discussion, including a substantial complement of graphics.
Union of Concerned Scientists (UCS): Backgrounder on the Midwest
Temperature Increases (Heat Waves!)
• Large heat waves have been more frequent in the Midwest since the 1980s than any time in the last century, excluding the Dust Bowl years of the 1930s. As the warming trend continues, “heat waves that are more frequent, more severe, and longer-lasting are projected. Events like the Chicago heat wave of 1995, which killed over 700 people, will become more common.
o “Under a lower emissions scenario, similar heat waves are expected to occur every other year by the end of the century, while under the higher emissions scenario, there would be approximately three such heat waves per year.”
o Heat waves that are more severe still, such as the one that killed tens of thousands in Europe in 2003, “are projected to become more frequent in a warmer world, occurring as often as every other year in the Midwest by the end of this century under the higher emissions scenario.”
Precipitation: Droughts and Flooding
• “The Midwest has already and will continue to experience changes in the frequency, intensity, and distribution of precipitation.”
• When it does rain, it rains harder: “One of the clearest precipitation trends in the United States is the increasing frequency and intensity of heavy downpours.” “Heavy downpours are now twice as frequent as they were a century ago.” “The amount of precipitation falling in the heaviest 1 percent of rain events increased nearly 20 percent. During the past 50 years, the greatest increases in heavy precipitation occurred in the Northeast and the Midwest.”
• More intense flooding is more likely: “Flooding from increasingly intense downpours will increase the risk of disruptions and delays in air, rail, and road transportation, and damage from mudslides in some areas.” “Over the last century, there was a 50 percent increase in the frequency of days with precipitation over 4 inches in the upper Midwest.”
o “[I]ntense precipitation is likely to increase the frequency and severity of events such as the Great Flood of 1993, which caused catastrophic flooding along 500 miles of the Mississippi and Missouri river system, paralyzing surface transportation systems, including rail, truck, and marine traffic. Major east-west traffic was halted for roughly six weeks in an area stretching from St. Louis, Missouri, west to Kansas City, Missouri and north to Chicago, Illinois, affecting one-quarter of all U.S. freight, which either originated or terminated in the flood-affected region. The June 2008 Midwest flood was the second record-breaking flood in the past 15 years. Dozens of levees were breached or overtopped in Iowa, Illinois, and Missouri, flooding huge areas, including nine square miles in and around Cedar Rapids, Iowa. Numerous highway and rail bridges were impassable due to flooding of approaches and transport was shut down along many stretches of highway, rail lines, and normally navigable waterways.” Increases in such events are likely to cause greater property damage, higher insurance rates, a heavier burden on emergency management, increased clean-up and rebuilding costs, and a growing financial toll on businesses, homeowners, and insurers.”
• Even with these heavier rains predicted, the Midwest is not immune from drought. In the summer, as evaporation rates and periods between rainfalls increase, the likelihood of drought will rise and water levels in rivers, streams, and wetlands are likely to decline. Lower water levels could also create problems for river traffic, reduce the recharge of groundwater, cause small streams to dry up (adversely affecting native fish populations), and reduce the area of wetlands in the Midwest.
Abrupt climate change:
“There is also the possibility of even larger changes in climate than current scenarios and models project. Not all changes in the climate are gradual… Earth’s climate patterns have undergone rapid shifts from one stable state to another within as short a period as a decade. The occurrence of abrupt changes in climate becomes increasingly likely as the human disturbance of the climate system grows. Such changes can occur so rapidly that they would challenge the ability of human and natural systems to adapt. Examples of such changes are abrupt shifts in drought frequency and duration. Ancient climate records suggest that in the United States, the Southwest may be at greatest risk for this kind of change, but that other regions including the Midwest and Great Plains have also had these kinds of abrupt shifts in the past and could experience them again in the future.” (emphasis added)
“Climate change impacts present many health risks for Midwesterners, from declining air quality to an increase in insect and waterborne disease. A warmer climate generally means more ground-level ozone (a component of smog), which can cause respiratory distress, especially for those who are young, old, or already suffer from respiratory problems. As the Midwest warms, insects such as ticks and mosquitoes that carry diseases like West Nile virus will be able to survive winters more easily and sustain larger populations. Warmer conditions allow more pathogens to thrive, causing an increase in the instance of waterborne diseases.
Effects on Aquatic Ecosystems:
Freshwater lakes need to “turn over” during the summer months in order to get oxygen down to the lower levels. But as water temperatures increase, there will be an earlier and longer period in summer during which “mixing of the relatively warm surface lake water with the colder water below is reduced.” This stratification acts to cut off oxygen from bottom layers, increasing the risk of oxygen-poor or oxygen-free “dead zones” that are fatal to fish and other living things. “Warmer water and low-oxygen conditions in the bottom layer of lakes also mobilize mercury and other contaminants in lake sediments. These increasing quantities of contaminants will be taken up in the aquatic food chain, adding to the existing health hazard for species that eat fish from the lakes, including people. Ecosystem disruptions resulting from invasions of non-native species, and the decline of native species, are also expected.”
Climate change effects on agriculture:
Although a warming climate may produce some positive effects in terms of crop production, the net impact of climate change on agriculture in the Midwest is expected to be negative: “the projected increase in winter and spring precipitation and flooding is likely to delay planting and crop establishment.” The positive effects that longer growing seasons and increased carbon dioxide have on some crop yields are “likely to be counterbalanced at least in part by the negative effects of additional disease-causing pathogens, insect pests, and weeds (including invasive weeds).” In addition, “livestock production is expected to become more costly as higher temperatures stress livestock, decreasing productivity and increasing costs associated with the needed ventilation and cooling equipment.” The ability of plants to thrive in their current environments will be affected by the warming climate: “by the end of the century, plants now associated with the Southeast are likely to become established throughout the Midwest.”
Issues for Planning and Preparedness in the Midwest
Several midwestern states have developed some sort of “climate change action plan” that addresses ways the state can take steps to reduce GHG emissions. Very little is in these plans on planning and preparedness for climate impacts, to promote adaptation.
Links for each of the midwestern states’ primary website for climate change appears below (from the Center for Climate Strategies website).
A separate, sister post will provide examples of steps being taken to effectively plan and prepare for climate change impacts, and identify areas where much more attention needs to be focused in order to reduce vulnerability and risk, and build in additional resiliency to climate disruption.
States without links do not yet have a climate action plan.