Climate Change and Possible Impacts on US Plant and Animal

Agriculture

Eugene S. TakleProfessor of Agricultural Meteorology, Department of Agronomy

Professor of Atmospheric Science, Department of Geological and Atmospheric SciencesIowa State Universitygstakle@iastate.edu

2005 Seeds and Breeds Conference, 11-14 September 2005, Ames, IA

Climate Change

• What is changing?• How much is it changing?• Why is it changing?• How might it affect agriculturalists?• What should we do about it?

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

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

JJA Daily Maximum Temperature Trends, 1976-2000

“Warming Hole”

TTmaxmax (JJA) (JJA)˚C

Solar IR IR Latent Conv & Cond

Soil

T

Surface Energy Balance

Solar IR IR Latent Conv & Cond

Soil

T

Surface Energy Balance

Hansen, Scientific American, March 2004

Mt. Pinatubo (1991)

El Chichon (1982)Agung, 1963

Carbon Dioxide and Temperature

2004(377ppm)

Carbon Dioxide and Temperature

“Business as Usual”(fossil intensive)

2100

Carbon Dioxide and Temperature

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http://www.earth-policy.org/Indicators/CO2/2004.htm

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Source: Jerry Meehl, National Center for Atmospheric Research

V V V

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Emanual, Kerry, 2005: Increasing destructiveness of tropical cyclones over the past 30 years. Nature, 436, 686-688.

Sea-surface temperature

V VV

Tropical Atlantic OceanHurricane Power Dissipation Index (PDI)

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Sea-Surface Temperatures in August 2005

Weather Underground: http://www.wunderground.com/tropical/

Source: National Center for Atmospheric Research

Source: National Center for Atmospheric Research

The planet is committed toa warming over the next 50 years regardless of political decisions

40% Probability

5% Probability

Source: Intergovernmental Panel on Climate Change, 2001 Report

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 Frost-free 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

+ already observed** North American Regional Climate Change Assessment

Program is underway but results for impacts won’t be available for several months.

Climate Change Impacts on Food Animals (my speculations)

• Lower breeding success in warmer temperatures• More freeze thaw cycles in beef-raising regions of the

Midwest (more sickness)• Reduced milk production in warmer temperatures• Poleward movement of tropical disease zones• Reduced weight gain by meat animals due to heat

stress in warmer temperatures• More intense rain events -> more care in manure

management• More favorable conditions for meat animal production

in Canada, Russia

Climate Change Impacts on Agricultural Plants (my speculations)

• Increase in CO2– increase in water-use efficiency by plants and

accelerated growth• Increase in night-time temperatures

– Higher night-time respiration by plants– Higher soil respiration and loss of soil carbon– Less dewfall

• Increase in daytime maximum temperatures– More heat waves, more heat stress– Reduced success for pollination

Climate Change Impacts on Agricultural Plants (my speculations)

• Altered large-scale weather patterns– Changed patterns for spread of air-borne pathogens

• Changes in precipitation– Increased amount -> more soil erosion, more nitrate

leaching– Larger fraction of total rain will come in heavy rain events

and may produce more floods and droughts– Longer periods between rains reduces some fungal

outbreaks– Possible changed seasonality – Possible changed diurnal patterns -> changes in soil

moisture

Climate Change Impacts on Agricultural Plants (my speculations)

• Increased overwintering of pests and pathogens• Higher absolute humidity -> more pathogens• Decreased mean wind speed

– Reduced lateral spread of pollen, pesticides, pathogens

• Deeper atmospheric boundary layer (lowest mile of the atmosphere)– More vertical mixing of pollen, pesticides,pathogens– More opportunity for long-range transport

Mitigation vs. Adaptation:Since we are already committed to a global

warming of about 2-4o F over the next 40 years we need to focus on:

• Adaptation to climate change for food security in the next half decade

• Mitigation of continued rise in greenhouse gases so our (great)n -grand children will have as many opportunities as we have had.

• More dialog between agriculturists and climate scientists to help prioritize climate research efforts.

For More Information

For peer-reviewed evidence supporting these slides (except some of my speculations), see my online Global

Change course:http://www.meteor.iastate.edu/gccourse

Contact me directly:gstakle@iastate.edu

For a copy of this presentation: http://www.meteor.iastate.edu/faculty/takle/