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1 Image courtesy of NASA/GSFC

2 Impact of Weather Extremes and Climate Change on Midwest Agriculture Eugene S. Takle Professor Department of Agronomy Department of Geological and Atmospheric Science Director, Climate Science Program Iowa State University Ames, IA North American Millers Associa1on Division Mee;ng Palm Coast, FL 25 March 2013

3 Outline CO 2 and grain quality Recent trends in temperature and precipitation Farmer adaptation to climate change Projected future changes in US climate What about the future: droughts or floods? Future shifts in US grain-producing regions

4 Global CO 2 and Mean Temperature

5 Impact of CO 2 Increases on Grain Quality Low nitrogen levels in soil are known to reduce grain quality in wheat, and this is further exacerbated in high CO 2 At low nitrogen levels, protein content was reduced by 39% under elevated CO 2 compared to a 33% reduc;on under ambient CO 2 In a study of wheat quality at low nitrogen availability it was found that loaf volume was reduced by 29% compared to 22% at elevated vs. ambient CO 2

6 Iowa State- Wide Average Data

7 Des Moines Airport Data Number of Days Number of Days with a Maximum Temperature Greater Than or Equal to 100 F 1974: : : : Year

8 Des Moines Airport Data Number of Days Number of Days with a Maximum Temperature Greater Than or Equal to 100 F 1974: : : : 10 6 days 100 o F in 23 years Year

9 Des Moines Airport Data Number of Days Number of Days with a Maximum Temperature Greater Than or Equal to 100 F 1974: : : : 10 6 days 100 o F in 23 years 11 days in Year

10 Min Temperature ( F) Winter Average State- Wide Temperature Minimum R² = Max Temperature ( F) Winter Average State- Wide Temperature Maximum R² = Year Year Min Temperature ( F) Summer Average State- Wide Temperature Minimum R² = Max Temperature ( F) Summer Average State- Wide Temperature Maximum R² = Year Year

11 Min Temperature ( F) Winter Average State- Wide Temperature Minimum R² = Max Temperature ( F) Winter Average State- Wide Temperature Maximum R² = Year Year Min Temperature ( F) Summer Average State- Wide Temperature Minimum R² = Max Temperature ( F) Summer Average State- Wide Temperature Maximum R² = Year Year

12 Iowa State- Wide Average Data Total Annual State- Wide Average Precipita1on 50.0 Total Average Precipita1on (inches) R² = Year

13 Iowa State- Wide Average Data Total Annual State- Wide Average Precipita1on Total Average Precipita1on (inches) year Totals above 40 5 years R² = Year

14 Iowa State- Wide Average Data Total Annual State- Wide Average Precipita1on 50.0 Total Average Precipita1on (inches) R² = highly favorable precip for crops Year

15 Cedar Rapids, Iowa Data Cedar Rapids Total Annual Precipita1on (inches) R² = Total Precipita1on (inches) Year

16 Cedar Rapids, Iowa Data Cedar Rapids Total Annual Precipita1on (inches) R² = Total Precipita1on (inches) % increase Year

17 Cedar Rapids, Iowa Data Cedar Rapids Total Annual Precipita1on (inches) Total Precipita1on (inches) Years with more than 40 inches 2 18 R² = Year

18 One of the clearest trends in the United States observa;onal record is an increasing frequency and intensity of heavy precipita;on events Over the last century there was a 50% increase in the frequency of days with precipita;on over mm (four inches) in the upper midwestern U.S.; this trend is sta;s;cally significant Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

19 Cedar Rapids, Iowa Data 14 Cedar Rapids Precipita1on Days per Year with Greater Than or Equal to 1.25 inches Number of Days Year

20 14 Cedar Rapids, Iowa Data Cedar Rapids Precipita1on Days per Year with Greater Than or Equal to 1.25 inches Creates runoff Number of Days Year

21 Cedar Rapids, Iowa Data 14 Cedar Rapids Precipita1on Days per Year with Greater Than or Equal to 1.25 inches Number of Days days 69% increase 6.1 days Year

22 Cedar Rapids, Iowa Data Cedar Rapids Precipita1on Days per Year with Greater Than or Equal to 1.25 inches Number of Years with More than 8 Occurrences 0 9 Number of Days Year

23 Photo courtesy of RM Cruse

24

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26 Spring Amplifica1on of the Seasonality of Precipita1on Fall Summer Winter

27 Spring Amplifica1on of the Seasonality of Precipita1on Fall Summer Winter

28 Spring Amplifica1on of the Seasonality of Precipita1on Fall Summer 21.2 => 25.3 inches (22% increase) 12.1 => 10.5 inches (13% decrease) Winter

29 Iowa Agricultural Producers are Adapting to Climate Change: Longer growing season: plant earlier, plant longer season hybrids, harvest later Wetter springs: larger machinery enables planting in smaller weather windows More summer precipitation: higher planting densities for higher yields Wetter springs and summers: more subsurface drainage tile is being installed, closer spacing, sloped surfaces Fewer extreme heat events: higher planting densities, fewer pollination failures; and planting seeds with a variety of pollination periods Higher humidity: more spraying for pathogens favored by moist conditions. more problems with fall crop dry-down, wider bean heads for faster harvest due to shorter harvest period during the daytime. Drier autumns: delay harvest to take advantage of natural dry-down conditions, thereby reducing fuel costs HIGHER YIELDS!! Is it gene;cs or climate? Likely some of each.

30 Precip Normal 2012 Normal 1988 Accum deficit Normal 2012 Stress Accum stress 1988 Normal 1988 was Hofer in August

31 Precip Normal 2012 Normal inches (30 cm) below normal going into 2013 Normal 2012 Stress Accum stress Normal 1988 was Hofer in August

32

33 Mean Summer (JJA) Dew-Point Temperatures for Des Moines, IA Rise of 3 o F in 42 years 12% rise in water content in 42 years

34 So what about droughts in the future?

35 What can we expect in the future? Don Wuebbles

36 IPCC 2007

37 June- July- August Temperature Change 4.5 o F 5.4 o F A1B Emission Scenario minus

38 Higher Emissions Scenario, Number of Days Over 100ºF Recent Past, Average: days Lower Emissions Scenario, Average: days Don Wuebbles

39 Higher Emissions Scenario, Number of Days Over 100ºF Recent Past, Average: days Current Des Moines average is < 1.4 days per year over 100 o F Lower Emissions Scenario, Average: days Don Wuebbles

40 Projected Change in Precipitation: Midwest: Increasing winter and spring precipita1on, with drier summers More frequent and intense periods of heavy rainfall Uns;ppled regions indicate reduced confidence CAUTION: High Relative to uncertainty NOTE: Scale Reversed

41 Extreme weather events become more common Events now considered rare will become commonplace. Heat waves will likely become longer and more severe Droughts are likely to become more frequent and severe in some regions Likely increase in severe thunderstorms (and perhaps in tornadoes). Winter storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent. Don Wuebbles

42 Percent Changes in Crop Yield with Projected Changes in Annual Mean Temperature (not water or nutrient limited) California Central Valley Lee, J., S. DeGryze, and J. Six Effect of climate change on field crop produc;on in the California s Central Valley. Clima;c Change. 109(Suppl):S335- S353

43 Length of Grain Fill Period and Corn Yields: Impact of High Temperatures Illinois High nighnme temperatures reduce length of grain fill period Indiana The Climate Corpora;on (hfp:// 2012outlook/nighnme- heat- stress) Illinois High nighnme temperatures during grain fill period reduce yields Indiana

44 Iowa State- Wide Average Data Total Annual State- Wide Average Precipita1on Total Average Precipita1on (inches) years Totals above 40 5 years 2012 R² = Year

45 Iowa State- Wide Average Data Total Annual State- Wide Average Precipita1on Total Average Precipita1on (inches) years 5 years Totals above 40 Totals below 25 5 years 7 years 2012 R² = Year

46 Projected Future Variability in Growing Season Precipita1on for Iowa More extreme high precip years CJ Anderson, ISU More extreme low precip years

47 Future Variability in Growing Season Precipita1on for Iowa More extreme high precip years Lines drawn by eye CJ Anderson, ISU More extreme low precip years

48 Yield Change by Mid-Century: Maize

49 Yield Change by Mid-Century: Soybeans

50 Yield Change by Mid-Century: Wheat

51 Summary The climate of has been highly favorable for agriculture in Iowa and the US Midwest Higher precipitation of the last 40 years has suppressed Iowa daily max temperatures in summer; dry summers in the future will unmask underlying climate warming trend Frequency of precipitation extremes has increased Recent trends and future projections suggest higher frequency of both floods and droughts

52 For More Information: Climate Science Program Iowa State University