Impacts of Climate Change on Agriculture Projected future changes

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?

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

So what if CO2 goes up? BUT! 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

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.

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).

D. Herzmann, Iowa Environmental Mesonet 8

Fewer precipitation events More intense precipitation events Increased occurrence of damaging floods D. Herzmann, Iowa Environmental Mesonet 9

Food costs

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 11

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 12

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 13

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.

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.

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

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

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

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

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