Agriculture and Climate Change

1. Agriculture and Climate Change Eugene S. Takle Agronomy Department Geological and Atmospheric Science Department Iowa State University Ames, Iowa 50011 gstakle@iastate.edu Underwriting/Marketing Seminar, 30 March 2005

2. Outline • Evidence for global climate change • Future atmospheric carbon dioxide concentrations • Simulations of global climate and future climate change • Impacts of climate change for the US Midwest • “Climate surprises” • Social inequities and ethical issues surrounding climate change • Summary

3. Carbon Dioxide and Temperature

4. Carbon Dioxide and Temperature 2005

5. 2040 Carbon Dioxide and Temperature (440 ppm) 2005 (375 ppm)

6. Carbon Dioxide and Temperature Stabilization at 550 ppm

7. Carbon Dioxide and Temperature “Business as Usual” (fossil intensive) 2100

9. Associated Climate Changes • Global sea-level has increased 1-2 mm/yr • Duration of ice cover of rivers and lakes decreased by 2 weeks in N. Hemisphere • Arctic ice has thinned substantially, decreased in extent by 10-15% • Reduced permafrost in polar, sub-polar, mountainous regions • Growing season lengthened by 1-4 days in N. Hemisphere • Retreat of continental glaciers on all continents • Poleward shift of animal and plant ranges • Snow cover decreased by 10% • Earlier flowering dates • Coral reef bleaching Source: Intergovernmental Panel on Climate Change, 2001 Report

10. Mann, M. E., R. S. Bailey, and M. K. Hughes, 1999: Geophysical Research Letters 26, 759.

16. El Chichon (1982) Agung, 1963 Mt. Pinatubo (1991) Hansen, Scientific American, March 2004

17. Source: Jerry Meehl, National Center for Atmospheric Research

18. Source: National Center for Atmospheric Research

19. The planet is committed to a warming over the next 50 years regardless of political decisions Source: National Center for Atmospheric Research

20. Source: Intergovernmental Panel on Climate Change, 2001 Report

21. 40% Probability 5% Probability Source: Intergovernmental Panel on Climate Change, 2001 Report

22. Climate Change Projected for 2100 Rapid Economic Growth Slower Economic Growth

23. Source: IPCC, 2001: Climate Change 2001: The Scientific Basis

24. Source: IPCC, 2001: Climate Change 2001: The Scientific Basis

25. IPCC Summary for Policy Makers • An increasing body of observations gives a collective picture of a warming world and other changes in the climate system

26. IPCC Summary for Policy Makers • An increasing body of observations gives a collective picture of a warming world and other changes in the climate system • Emissions of greenhouse gases and aerosols due to human activities continue to alter the atmosphere in ways that are expected to affect the climate

27. IPCC Summary for Policy Makers, cont’d • Confidence in the ability of models to project future climate has increased

28. IPCC Summary for Policy Makers, cont’d • Confidence in the ability of models to project future climate has increased • There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities

29. IPCC Summary for Policy Makers, cont’d • Anthropogenic climate change will persist for many centuries

30. IPCC Summary for Policy Makers, cont’d • Anthropogenic climate change will persist for many centuries • Further action is required to address remaining gaps in information and understanding

31. Climate Surprises:Low Probability but High-Impact Events • Breakdown of the ocean thermohaline circulation (Greenland melt water) • Breakoff of the West Antarctic Ice Sheet

32. Antarctica Greenland Ice Volume 0 Warm Cold Climate

34. Meltwater flows into a large moulin on Greenland and down to the bedrock to "lubricate" the sheet BBC News: World Edition http://news.bbc.co.uk/2/hi/science/nature/2558319.stm

37. For the Midwest • Warming will be greater for winter than summer • Warming will be greater at night than during the day • A 3oF rise in summer daytime temperature triples the probability of a heat wave • Growing season will be longer (8-9 days longer now than in 1950) • More precipitation • Likely more soil moisture in summer • More rain will come in intense rainfall events • Higher stream flow, more flooding

38. Sub-Basins of the Upper Mississippi River Basin 119 sub-basins Outflow measured at Grafton, IL Approximately one observing station per sub-basin Approximately one model grid point per sub-basin

41. RegCM2 Simulation Domain Red = global model grid point Green/blue = regional model grid points

42. Ten-Year Mean Monthly Stream Flow Generated by the RegCM2 Regional Climate Model Driven with HadCM2 Global Model Results for the Contemporary and Future Scenario (2040s) Climate

43. Relation of Runoff to Precipitation for Various Climates More precip goes to streamflow in a future climate

44. “Warming Hole” ˚C DTmax (JJA)

45. Source: IPCC, 2001: Climate Change 2001: The Scientific Basis

46. Social Inequities due to Climate Change • Agricultural production • Freshwater availability • Sea-water innundation • Intergenerational equities

47. Social Inequities due to Climate Change • Agricultural production • Freshwater availability • Sea-water innundation • Intergenerational equities

50. Impact on US Agriculture(my speculations) • The US is a large enough country at a high enough latitude that it will have regional winners and losers • Areas now marginal for agriculture may become less suitable • Some areas now having abundant water but limited growing seasons may be winners • Areas with good soils and robust climate, like Iowa, may be impacted less • The US Midwest may experience more variability from year to year, which would make agricultural yields more variable (flooding, water-logging, drought) • Changes in consumption and agricultural production in other nations may affect US agriculture more than changes to US climate • Environmental refugees?