• A longer growing season will positively impact some crop yields through mid-century.
  • By the end of the century, more frequent and intense severe weather, more flooding and drought risks, as well as more pests and pathogens will likely reduce crop yields. 
  • Water availability and quality will likely pose challenges for agriculture.
  • Earlier warm spells, coupled with variability in spring freezes, may result in more freeze damage early in the growing season. 
Observed change in the frost-free season length in the United States. The Midwestern and Northeastern U.S. experienced an increase in the frost-free season of 9 and 10 days, respectively, from 1958-2012.Observed change in the frost-free season length in the United States. The Midwestern and Northeastern U.S. experienced an increase in the frost-free season of 9 and 10 days, respectively, from 1958-2012.
Projected change in frost-free (growing) season length by 2100 under continued increases in greenhouse gases. Data from Third National Climate Assessment.Projected change in frost-free (growing) season length by 2100 under continued increases in greenhouse gases. Data from Third National Climate Assessment.

Climate change will have both positive and negative impacts on agricultural yields in the Great Lakes region. A longer growing season and more atmospheric carbon dioxide may alter crop yields through the middle of the 21st century. Beyond that, however, crop yields may decrease as more extreme weather, stress from pests and weeds, and other factors outweigh the benefits of a more fertile atmosphere and soil.1 2 3 4 5

Changes in the timing and amount of precipitation may affect the amount and quality of water available for agricultural use. Increased precipitation in the spring and fall may decrease the number of workable field days during critical periods of planting and harvesting. And stronger and more frequent heavy precipitation events will increase erosion risks and reduce water quality by increasing runoff.1

Regional Variation of Climate Change Impacts

The potential benefits and risks also vary throughout the region. Northern Wisconsin agriculture, for example, is likely to benefit from climate change further into the future, due to its more northern location.4 By contrast, there has already been an observed decrease in crop yields in southern regions due to an increased number of summer days exceeding 86⁰F (30⁰C).6 

Potential Impacts Vary by Crop Type

Lands involved in agricultural production represent a significant portion of land use and form a major part of the economy in the Great Lakes region. Corn, soybeans, and wheat dominate the southern and western portions of the region while fruit, nuts, and specialty crops have been a signature of north and east parts of the Great Lakes region for more than 150 years.7 The potential vulnerabilities to a changing climate vary dramatically from row crops to perennial fruit crops. While new adaptation efforts can be applied on an annual basis to support most row crops, orchards and other fruit crops require several years to reach optimal yield, during which time major changes to growing practices are usually unfeasible.

Corn and Soybeans

For soybeans, yields have a two in three chance of increasing early in the near-future due to increased  carbon dioxide stimulation. Yields will likely decline towards the end of the century due to increased heat stress from the increased number of days with temperatures above 95 and 100°F. For corn, small long-term average temperature increases will shorten the duration of reproductive development, leading to yield declines, even when offset by increases in CO2 stimulation that will likely occur in a warmer climate.8 9 Impacts due to these factors will likely be most severe in more southerly located field cropping regions such as Missouri or southern Illinois.

Fruit Crops

Commercial fruit trees in the region will face both positive and negative impacts. These include the benefits of a longer growing season, but also increased pests and a higher sensitivity to cold temperatures that occur after bud break.10 5 11 In general, agricultural management will need to account for other climate change impacts, such as lower water tables.12 Many negative impacts of climate change on agriculture could potentially be avoided by using adaptive farming techniques, such as drought-resistant varieties of crops and more efficient irrigation systems.13 14

Frozen cherry buds

Warmer Temperatures and Increased Freeze Vulnerability

The Great Lakes growing season has lengthened by one to two weeks across the region, primarily due to earlier occurrence of the last spring frost in recent decades.2 15 Paradoxically, the frequency of spring freezes that occur after the initial phases of crop development have increased during the same time frame. This is likely due to warm-spells that are occurring earlier in the year that in the past, spurring earlier crop development. This has resulted in an increased risk of production losses with time.16 17 Several events in recent years have had a major impact on regional fruit production. In 2012, an unprecedented March heat wave over Michigan brought fruit crops out of dormancy more than a month ahead of normal. In April and May, a series of normally-timed freeze events resulted in cold damage, with tart cherry and apple yields being reduced by 90 and 88%, when compared to the previous annual yield.16 7 In 2012 and 2007 in the Northeast and in 2002 in Michigan, similar events severely impacted apple, grape, cherry, and other fruit crops.16 18

Changes in midwinter freeze-thaw patterns in more temperate portions of the region have also impacted fruit crops. For example, midwinter-freeze damage cost New York Finger Lakes wine grape growers millions of dollars in losses in the winters of 2003 and 2004.19 This damage was attributed to de-hardening of the vines during an unusually warm December, which increased susceptibility to cold damage prior to a subsequent hard freeze. Future crop yields will likely be affected more frequently by anomalous weather events like late winter cold air outbreaks coinciding with long-term changes in seasonality.20 21

Effects of Increasing Carbon Dioxide on Pests and Weeds

Increasing CO2 concentrations and temperatures will pose increased challenges to pest control in agricultural settings. For example, Roundup, the most widely-used herbicide in the United States, loses its efficacy on weeds grown at the CO2 levels likely to occur in the coming decades.22 For weeds and crops that process CO2 similarly (that share a photosynthetic pathway), weed growth is favored as CO2 is increased.23

External Resources

U.S. Drought Monitor: The U.S. Drought Monitor is a weekly map of drought conditions that is produced jointly by the National Oceanic and Atmospheric Administration, the U.S. Department of Agriculture, and the National Drought Mitigation Center (NDMC) at the University of Nebraska-Lincoln.

The Pileus Project: The overarching purpose of the Pileus Project is to provide useful climate information to assist decision makers. One of two current focus industries in the Great Lakes region is agriculture.


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  • 2. a. b. Karl T.R., Melilo J.M., Peterson T.C. (2009) Global Climate Change Impacts in the United States. USGCRP.
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  • 6. Warland J., McKeown A.W., McDonald M.R. (2006) Long-term climate and weather patterns in relation to crop yield: a minireview. Canadian Journal of Botany 84:1031.
  • 7. a. b. USDA NASS (2013) Crop Values 2012 Summary. Department of Agriculture National Agricultural Statistics Service, Washington D.C.
  • 8. Hatfield, J.L., Boote, K.J., Kimball. B.A., Ziska, L.H., Izaurralde, R.C., Ort, D., Thomson, A.M., and Wolfe, D. (2011): Climate impacts on agriculture: Implications for crop production. Agronomy Journal, 013, 351-370. doi:10.2134/agronj2010.0303
  • 9. Leakey, A.D.B. (2009): Rising atmospheric carbon dioxide concentration and the future of C4 crops for food and fuel. Proceedings of the Royal Society B: Biological Sciences, 276, 2333-2343. doi:10.1098/rspb.2008.1517
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  • 16. a. b. c. Yu, L., Zhong, S., Bian, X. , Heilman, W.E., and Andresen, J.A. (2014): Temporal and spatial variability of frost-free seasons in the Great Lakes region of United States. International Journal of Climatology, In Press. doi: 10.1002/joc.3923
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  • 19. Levin, M.D., 2005: FInger Lakes freezes devestate vineyards. Wines and Vines
  • 20. Cold air outbreaks are defined here as at least two consecutive days during which the daily average surface air temperature is below 95% of the simulated average wintertime surface air temperature.
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