MIDWEST

arming,manufacturing,and forestry characterize the Midwest. The Great F Lakes form the world's largest freshwater lake system,providing a major recreation area as well as a regional water transportation system with access to the Atlantic Ocean via the St.Lawrence Seaway. The region encompasses the headwaters and upper basin of the River and most of the length of the River, both critical water sources and means of industrial transportation providing an outlet to the Gulf of Mexico. The Midwest contains some of the richest farmland in the world and produces most of the Nation's corn and soybeans. It also has important metropolitan centers,including and Detroit. Most of the largest urban areas in the region are found along the Great Lakes and major rivers. The "North Woods" are a large source of forestry products and have the advantage of being situated near the Great Lakes,providing for easy transportation.

Observed Climate Trends

ver the 20th century, the northern portion of the Midwest,including the O upper Great Lakes,has warmed by almost 4ºF (2ºC),while the southern por- tion,along the Ohio River valley, has cooled by about 1ºF (0.5ºC). Annual precipita- tion has increased,with many of the changes quite substantial,including as much as 10 to 20% increases over the 20th century. Much of the precipitation has resulted KEY ISSUES from an increased rise in the number of days with heavy and very heavy precipita- tion events. There have been moderate to very large increases in the number of • Reduction in Lake and days with excessive moisture in the eastern portion of the basin. River Levels

• Health and Quality of Life Scenarios of Future Climate in Urban Areas uring the 21st century, models project that temperatures will increase • Agricultural Shifts D throughout the Midwest,and at a greater rate than has been observed in the 20th century. Even over the northern portion of the region,where warming has • Changes in Semi-natural been the largest,an accelerated warming trend is projected for the 21st century, and Natural Ecosystems with temperatures increasing by 5 to 10ºF (3 to 6ºC). The average minimum tem- perature is likely to increase as much as 1 to 2ºF (0.5 to 1ºC) more than the maxi- mum temperature. Precipitation is likely to continue its upward trend,at a slightly accelerated rate;10 to 30% increases are projected across much of the region. Despite the increases in precipitation,increases in temperature and other meteoro- logical factors are likely to lead to a substantial increase in evaporation,causing a soil moisture deficit, reduction in lake and river levels,and more drought-like condi- tions in much of the region. In addition,increases in the proportion of precipita- tion coming from heavy and extreme precipitation are very likely.

Climate Extremes Create the region, but the entire nation. Chicago is Prolonged heavy rainfall in the spring and Critical Transportation the nation's rail hub handling much of the summer of 1993 produced extensive flood- Problems nation freight traffic. Barges operating on ing across nine states in the upper Midwest. the Mississippi River system, that includes The flood waters poured over and through Climate extremes in the Midwest can drasti- the Ohio, , and Missouri Rivers, han- many levees and inundated numerous cally impede the highly weather-sensitive dle a large fraction of the country’s bulk floodplains that many of the key rail lines transportation systems that serve not only commodities, such as grain and coal. cross. The flood waters became an

52 An accelerated warming trend is projected for the 21st cen- tury, with temperatures increasing by 5 to 10˚F (3 to 6˚C). Precipitation is likely to continue its upward trend, at a slightly accelerated rate; 10 to 30% increases are projected across much of the region.

Temperature Change - 20th & 21st Centuries Observed 20th +15ºF Temperatures in the Midwest have Winter Minimum Temperature Change increased, with the largest observed 21st Century Average +10ºF changes for the region in Minnesota and the Upper Peninsula of . Canadian Model Hadley Model +5ºF Model scenarios suggest further +15ºF increases over the 21st century from 0º near 5ºF (Hadley model) to more than +10ºF 10ºF (Canadian model). -5ºF +5ºF Canadian Model 21st Hadley Model 21st +15ºF +15ºF 0º

-5ºF +10ºF +10ºF Both climate models indicate that the northern part of the +5ºF +5ºF Midwest will experience the largest increases in winter temperatures. The Canadian Model suggests the greatest 0º 0º increases, approaching 15ºF in Minnesota and the Upper Peninsula of Michigan. -5ºF -5ºF

Precipitation Change - 20th & 21st Centuries

Observed 20th Canadian Model 21st Hadley Model 21st On average, 100% 100% The Hadley model indicates 75% 80% Midwest 60% that this trend will continue, 50% precipita- 40% resulting in increases of tion over 25% 20% about 25% from the present. the 20th 0 0 The Canadian model suggests -20% century has -25% that these increases will be -50% -40% increased. -60% confined to the northern and -75% -80% western parts of the region. -100% -100%

absolute barrier to surface transportation in This came on the heels of the 1988 the region for more than six weeks. Train drought that also had a major impact on traffic had to be rerouted around the flood barge shipping due to low river levels, illus- area, resulting in long delays and large trating the sensitivity of transportation sys- costs to manufacturing. River barge traffic tems to both wet and dry climate extremes. suffered a similar fate with the additional costs to shipping and manufacturing approaching $2 billion.

53 MIDWEST KEY ISSUES

Reduction in Lake and River Levels

ater levels,supply, quality, and water-based transportation and recreation W are all climate-sensitive issues affecting the region. Despite the project- ed increase in precipitation,increased evaporation due to higher summer air temperatures is likely to lead to reduced levels in the Great Lakes.Of 12 models used to assess this question,11 suggest significant decreases in lake levels while one suggests a small increase. The total range of the 11 models' projections is less than a one-foot increase to more than a five-foot decrease. A five-foot (1.5- meter) reduction would lead to a 20 to 40% reduction in outflow to the St. Lawrence Seaway. Lower lake levels cause reduced hydropower generation downstream,with reductions of up to 15% by 2050. An increase in demand for The projected increase in water across the region at the same time as net flows decrease is of particular concern. There is a possibility of increased national and international tension very heavy precipitation related to increased pressure for water diversions from the Lakes as demands events will likely worsen for water increase. For smaller lakes and rivers, reduced flows are likely to agricultural and other non- cause water quality issues to become more acute. In addition,the projected point source pollution as increase in very heavy precipitation events will likely lead to increased flash flooding and worsen agricultural and other non-point source pollution as more more frequent heavy rains frequent heavy rains wash pollutants into rivers and lakes. Lower water levels wash pollutants into rivers are likely to make water-based transportation more difficult with increases in and lakes. the costs of navigation of 5 to 40%. Some of this increase will likely be offset as reduced ice cover extends the navigation season. Shoreline damage due to high lake levels is likely to decrease 40 to 80% due to reduced water levels. Lower water levels are likely to make water-based trans- Adaptations: A reduction in lake and river levels would require adaptations portation more difficult with such as re-engineering of ship docks and locks for transportation and recre- ation. If flows decrease while demand increases,international commissions increases in the costs of focusing on Great Lakes water issues are likely to become even more important navigation of 5 to 40%. in the future.Improved forecasts and warnings of extreme precipitation events could help reduce some related impacts.

Lake Ice Duration at Lake Mendota 180 Madison, Wisconsin 142 Years (1856 - 1998)

150

120

90

60

Lake ice duration has decreased by nearly one month over the past 150 30 years, with a record low in the winter of 1997-98. This is consistent with observed increases in temperature. 0 1850 1900 1950 2000 54 Health and Quality of Life in Urban Areas During the summer, in cities, heat-related stresses are reduction in extremely low temperatures and an increase in extremely very likely to be exacerbated A high temperatures are expected. Thus,a reduced risk of life-threatening cold and an increased risk of life-threatening heat are likely to accompany by the urban heat island warming. Reduced expenditures on snow and ice removal and fewer snow and effect, a phenomenon in ice related accidents and delays are likely. During the summer, however, in which cities remain much cities,heat-related stresses are very likely to be exacerbated by the urban heat island effect,a phenomenon in which cities remain much warmer than sur- warmer than surrounding rounding rural areas. This elevates nighttime temperatures,and in combination rural areas. with the greater expected rise of nighttime temperatures compared to those of daytime,there will be less relief at night during heat waves. Elevated nighttime temperatures were a notable characteristic of the 1995 that resulted Elevated nighttime tempera- in over 700 deaths in Chicago. In addition,during heat waves in the Midwest, tures were a notable charac- air pollutants are trapped near the surface,as atmospheric ventilation is teristic of the 1995 heat reduced. Without strict attention to regional emissions of air pollutants,the wave that resulted in over undesirable combination of extreme heat and unhealthy air quality is likely to result. There is also a possibility of an increased risk of water-borne diseases 700 deaths in Chicago. with increases in extreme precipitation events,and increased insect- or tick- borne diseases,such as St.Louis encephalitis. Recreational activities will very likely shift as cold-season recreation such as skiing,snowmobiling,ice skating, and ice-fishing,are reduced,and warm-season recreation such as swimming,hik- ing,and golf, are expanded,although during mid-summer, these activities are likely to be affected by excessive heat.

Adaptations: Active responses,such as those taken by Chicago during the 1999 heat wave,are likely to help reduce the death toll due to extreme heat. Separate storm water and sewer lines and other appropriate preventative meas- ures can help mitigate the possible increased risk of water-borne diseases.

Canadian Model Hadley Model

Summer Precipitation Summer Average Temperature

Illustration of how the summer climate of Illinois would shift under the Canadian and Hadley model scenarios. Under the Canadian scenario, the summer climate of Illinois would become more like the current climate of southern Missouri in 2030 and more like Oklahoma's current climate in 2090. The primary difference in the resulting climates of the two models relates to the amount of sum- mer rainfall.

55 MIDWEST KEY ISSUES

yields are not likely to increase in all technologies are additional options. parts of the region. For example,in There is also the potential for shifting the southern portions of and or expanding the area where certain Illinois,corn yields are likely to crops are grown if climate conditions decline,with 10-20% decreases pro- become more favorable. Weather jected in some locations. Consumers conditions during the growing season are likely to pay lower prices due to are the primary factor in year-to-year generally increased yields,while most differences in corn and soybean Agricultural Shifts producers are likely to suffer reduced yields. Droughts and floods result in profits due to declining prices. large yield reductions;severe griculture is of vital importance Increased use of pesticides and herbi- droughts,like the drought of 1988, A to this region,the nation,and cides are very likely to be required cause yield reductions of over 30%. the world. It has exhibited a capacity and to present new challenges. Reliable seasonal forecasts are likely to adapt to moderate differences in to help farmers adjust their practices growing season climate,and it is like- Adaptations: Plant breeding pro- from year to year to respond to such ly that agriculture would be able to grams can use skilled climate predic- events. continue to adapt. With an increase tions to aid in breeding new varieties in the length of the growing season, for the new growing conditions. double cropping,the practice of Farmers can then choose varieties planting a second crop after the first that are better attuned to the expect- is harvested,is likely to become more ed climate. It is likely that plant prevalent. The CO2 fertilization effect breeders will need to use all the tools is likely to enhance plant growth and of plant breeding,including genetic contribute to generally higher yields. engineering,in adapting to climate The largest increases are projected to change.Changing planting and har- occur in the northern areas of the vest dates and planting densities,and region,where crop yields are current- using integrated pest management, ly temperature limited. However, conservation tillage,and new farm Farm flooded by Mississippi river in 1993.

Midwest Soybean Yield and Precipitation 2.0 8 1.9 6 1.8

1.7 4 1.6 The relationship between 1.5 2 Midwest soybean yield and pre- 1.4 cipitation is shown here. 0 Soybean yields in thousands of 1.3 bushels are shown as the differ- 1.2 -2 ences from the average yield in 1.1 recent decades. Precipitation is -4 the difference from the 1961-90 1.0 average precipitation. Note that 0.9 lower yields result from both -6 extreme wet and extreme dry 0.8 conditions. 0.7 -8 1975 1980 1985 1990 1995

56 Changes in Semi-natural and greater environmental stress on both lands could gradually migrate,but in Natural Ecosystems deciduous and coniferous trees,mak- areas where their migration is limited ing them susceptible to disease and by the topography, they would disap- he upper Midwest has a unique pest infestation,likely resulting in pear. Changes in bird populations T combination of soil and climate increased tree mortality. and other native wildlife have already that allows for abundant coniferous been linked to increasing tempera- tree growth. Higher temperatures As water temperatures in lakes tures and more changes are likely in and increased evaporation will likely increase,major changes in freshwater the future. Wildlife populations are reduce boreal forest acreage,and ecosystems will very likely occur, particularly susceptible to climate make current forestlands more sus- such as a shift from cold water fish extremes due to the effects of ceptible to pests and diseases. It is species,such as trout,to warmer drought on their food sources. likely that the southern transition water species,such as bass and cat- zone of the boreal forest will be sus- fish. Warmer water is also likely to ceptible to expansion of temperate create an environment more suscepti- ble to invasions by non-native forests, which in turn will have to Runoff of excess compete with other land use pres- species. Runoff of excess nutrients sures. However, warmer weather (such as nitrogen and phosphorus nutrients (such as (coupled with beneficial effects of from fertilizer) into lakes and rivers is nitrogen and phos- likely to increase due to the increase increased CO2),are likely to lead to phorus from fertilizer) an increase in tree growth rates on in heavy precipitation events. This, marginal forestlands that are current- coupled with warmer lake tempera- into lakes and rivers ly temperature-limited. Most climate tures,is likely to stimulate the is likely to increase models indicate that higher air tem- growth of algae,depleting the water due to the increase in of oxygen to the detriment of other peratures will cause greater evapora- heavy precipitation tion and hence reduced soil moisture, living things. Declining lake levels a situation conducive to forest fires. are likely to cause large impacts to events. As the 21st century progresses,there the current distribution of wetlands. will be an increased likelihood of There is some chance that some wet-

Projected Midwest Daily Precipitation 21st Century Canadian Model Hadley Model 60 60 50 50 40 40 30 30 20 20 10 10 0 0 -10 -10 -20

LightestLight 5% LightestLight 5%

ModerateModerate ModerateModerate Heaviest 5% Heaviest 5% Heavy Heavy Days receiving precipitation, sorted by percentile. Percentiles Percentiles

Annual trends in daily precipitation by percentile for the Canadian and Hadley model scenarios for the 21st century. Notice the largest trend is in the heaviest daily precipitation amount for both model simulations, indicating that most of the projected increase in annual precipitation will be due to an increase in precipitation on days already receiving large amounts.

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