1. Impacts of Climate Change on Agriculture
Projected future changes
Assembled by Brian Viner and Gene Takle

2. Questions to consider
The U.S. Climate Change Science Program (CCSP) focused on the following questions:
What factors influencing agriculture, land resources, water resources, and biodiversity in the United States are sensitive to climate and climate change?
How could changes in climate exacerbate or ameliorate stresses on agriculture, land resources, water resources, and biodiversity?
What are the indicators of these stresses?

3. Potential Agricultural-Related Impacts from Climate Change
Droughts and low water-tables leading to water stress
Transport of water to other locations
Warmer temps leading to more pests and diseases
Changing seasons will lead to different crop growth.
Soil temperatures will remain warmer

4. So what if CO2 goes up?
Carbon dioxide is also the source of carbon for photosynthesis,
and consequently for 99% of all life.
Plants are the only organisms that can convert light energy into chemical energy. Consequently, they are at the bottom of every food chain.
CO2 + H2O + light  O2 + organic C + chemical energy

5. Impacts biophysical impacts:
physiological effects on crops, pasture, forests and livestock (quantity, quality);
changes in land, soil and water resources (quantity, quality);
increased weed and pest challenges;
socio-economic impacts:
decline in yields and production;
reduced marginal GDP from agriculture;
fluctuations in world market prices;
changes in geographical distribution of trade regimes;
increased number of people at risk of hunger and food insecurity;
migration and civil unrest.

6. More impacts
Food production is projected to benefit from a warmer climate, but there probably will be strong regional effects.
Additional CO2 is expected to improve crop yield and biomass production
The U.S. Great Plains/Canadian Prairies are expected to be particularly vulnerable.
Crops that are currently near climate thresholds (e.g., wine grapes in California) are likely to suffer decreases in yields, quality, or both.
Climate change is expected to improve growing conditions for some crops that are limited by length of growing season and temperature. (e.g. fruit production in the Great Lakes region and eastern Canada).

8. D. Herzmann, Iowa Environmental Mesonet8

9. D. Herzmann, Iowa Environmental Mesonet9

10. D. Herzmann, Iowa Environmental Mesonet10

11. Fewer precipitation events More intense precipitation events
Increased occurrence of damaging floods
D. Herzmann, Iowa Environmental Mesonet 11

12. Sensitivity of Maize Yield to Climate Change
Red= without adaptation
Black=with adaptation (change planting date, cultivar, use of irrigation)
IPCC, 2007:Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 976pp. Chapter 5.

14. Food costs

16. Reasons for Crop Increases
Longer growing season
Warmer spring soil temperatures
Modest or no increase in summer daily maximum temperatures
Increase in nighttime temperatures
Reduced risk of late frost in spring or early frost in fall
More freeze-thaw cycles that will recharge soil moisture in winter 16

17. Reasons for Crop Increases
More precipitation
More soil moisture
Higher dew-point temperatures reduces moisture stress
Increased carbon uptake by crops
Higher CO2 increases the water-use efficiency of crops 17

18. Reasons for Crop Decreases
More precipitation extremes
More rain events bring heavy rain
More droughts
More floods
More over-wintering pests
More pathogens due to higher humidity
More vigorous weed growth
More efficient water use => less cooling 18

19. Which Cow Will Be Affected More by the Sun?
Radiant energy from the sun can be a major contributing factor to heat stress. Darker coated animals tend to absorb more radiant heat and will be more affected by heat stress.

20. Example of the Interaction of Temperature and Humidity in Determining Heat Stress Potential in Dairy Cattle
A Dairy Heat Stress Chart provided by Diamond V. This company manufactures yeast culture for inclusion in animal feeds. This lists 5 different zones of heat stress based on information from the University of Arizona. A key thing to point out is that the effect of heat stress at a specific temperature varies with relative humidity. As an example, there is no heat stress at a temperature of 83 F and 20% relative humidity. However, the animal is distressed at a temperature of 83 F and 90% relative humidity.

21. Potential types of adaptation
Seasonal changes and sowing dates
Different variety or species
Water supply and irrigation system
Other inputs (fertilizer, tillage methods, grain drying, other field operations)
New crop varieties

22. How might Agriculture be Affected by Mitigation Legislation?
Agriculture may need to reduce emissions because it releases substantial amounts of methane, nitrous oxide, and carbon dioxide.
50% of total methane, 70% of nitrous oxide, and 20% of carbon dioxide

23. How might Agriculture be Affected by Mitigation Legislation?
Agriculture may enhance its absorption of GHGE by creating or expanding sinks.
Management practices can increase soil carbon retention
Land retirement (conversion to native vegetation)
Residue management
Less-intensive tillage
Land use conversion to pasture or forest
Restoration of degraded soils

24. How might Agriculture be Affected by Mitigation Legislation?
Agriculture may provide substitute products which replace fossil fuel intensive products.
- Cotton and other fibers can also be used to reduce petroleum-based synthetics
Agriculture may find itself operating in a world where commodity and input prices have been altered by GHG related policies.
- Increasing fuel taxes and transportation costs will be passed to the consumer

25. Information Taken From:
IPCC 4th Assessment Report
Climateandfarming.org