Impacts of Climate Changeon Agriculture Assembled by Brian Viner and Gene Takle
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? Carbon dioxide is also the source of carbon for photosynthesis, and consequently for 99% of all life. 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).
Fewer precipitation events More intense precipitation events Increased occurrence of damaging floods D. Herzmann, Iowa Environmental Mesonet
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
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.
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
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
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
Example of the Interaction of Temperature and Humidity in Determining Heat Stress Potential in Dairy Cattle
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