Global Climate Change and Its Impact on Food Production and Biofuels

From a geological view, coal, oil, and natural gas are the major economic entities in the carbon cycle. However, in your lifetime and mine, food and biofuels are the major economic entities in the carbon cycle. (Pharmaceuticals, plant oil lubricants, and other consumer products are also economic entities, perhaps higher value but lower volume.) Plants consume carbon dioxide, food and biofuels are the major end-use products, and their burning or catabolism puts carbon not held in plant roots back into the atmosphere.

Though the credibility of science and scientists has suffered from Climategate-related revelations of the past four months and the inexactness of climate measurement has been underlined, certain realities remain. Atmospheric carbon dioxide has increased, methane and nitrous oxide are measurable, public concern regarding these atmospheric components is real, and policy uncertainty prevails.

Agricultural producers can increase capture of atmospheric carbon and nitrogen (increase nitrogen fixation and carbon absorption, more plant growth per acre), limit their soil release by choosing tillage and other practices, and control input volume of fossil fuel, purchased nitrogen, and lime (calcium carbonate) per acre. Consequently, producers are in a position to mitigate negative C and N consequences, and perhaps to profit from doing so (convert methane to economic use, rotation grazing, transfer payments). Producers are also in a position to be regulated (input or emission limits or processes).

Can agriculture adapt to climate change? Agriculture’s success is a vivid story of continuous adaptation – to climate, soil, and the market. In the late 1880s the S.D. Agricultural Experiment Station Report indicated the new crop, corn, was “doing well at Flandreau (40 miles north of Iowa’s NW corner) but would likely never get as far north as Brookings (another 40 miles). From 1968 to 1983, the edge of the Corn Belt in S.D. moved another 100 miles north and west. And, today, we have DNA manipulations and precision in cultural practices that can speed adaptation.

In today’s discussion, you and I may seek answers to such questions as: Is agriculture better off with an established climate policy or with uncertainty? Is plant or animal adaptation limited? Where should I (farmer, experiment station or extension director, state agency head, legislator) invest time and money, relative to this issue? What message should I tell my neighbor? What message should I send to my legislator?

This presentation, in coordination with brief presentations in the afternoon breakout sessions, will provide a critical examination of climate modeling as a basis for assessing global climate change and its impacts. An overview of observed variability and changes in the global surface and upper air temperature, ocean heat content, land and ice masses, hurricane intensity, wildfire frequency, and weather-related insurance losses over the 20th century will be presented. Alternative sources of global energy supply and redistribution over the earth will be considered as drivers for these observed changes. The scientific basis underpinning climate change will be discussed, and global climate model results will be compared with observed climate conditions from the 20th century. Changes projected by global climate models for the 21st century will be used as a basis for comparison with recent observed trends in the Midwest. A review of climate factors specifically relevant to agriculture over the past 30 years will be used as a backdrop for interpreting yield changes and producer adaptations. Recent changes in planting dates, planting densities, machinery, pathogens, drainage tile installation, and harvest strategies will be interpreted in the context of climate change. Projected future climate for the Midwest by global and regional climate models will be used to provide an overview of possible impacts of climate change on the agriculture in the Midwest over the 21st century.

There is an enormous range of policy options for reducing greenhouse gas emissions. Important debates continue about which policies should be pursued and, more importantly, the process through which policies should be selected and prioritized.

Two broad approaches have been considered and applied in various contexts. Traditionally, regulation or legislation has identified specific technologies as the “best available” option and mandated (or subsidized) the adoption of such technologies. In recent years, “market-based” regulatory approaches such as the cap and trade of emissions allowances have gained favor. Under market-based approaches, the decisions about who and how to reduce emissions are much more decentralized.

The question of overall policy choice is further complicated by a myriad of overlapping federal and local regulations and by extensive trade with regions whose emissions may not be regulated at all. Carbon offsets fit into this picture as a tool for potentially tapping low-cost options for emissions reductions. Offsets also offer the promise of extending the reach of regulations by supporting reductions in industries and countries that would not otherwise have an incentive to do so. The extent to which the promise of market-based regulations can be realized will depend upon the structure of the markets, the incentives of players, and the information available to both regulators and market participants.

Because fossil fuels are the primary source of greenhouse gas emissions, any serious effort aimed at reducing the growth in atmospheric greenhouse gas concentrations will need to focus on making fossil fuels more costly to use. Costlier fossil fuels will increase agricultural production costs and will generate new demand for agricultural products.

Production costs will rise because fossil fuels are used directly by farmers to dry their grain and fuel their tractors and trucks and because the production of fertilizer and chemicals is energy intensive. Just as the prices of fertilizer and chemicals will rise to reflect their higher production costs, so too will commodity prices to reflect higher farm-level production costs. The extent to which higher farm production costs are offset by higher commodity prices depends, in part, on whether farmers in the rest of the world will also face higher fossil fuel prices. If faced with the prospect of higher fossil fuel prices, it is in the interest of U.S. domestic producers to lobby for global policies that do not change current patterns of global competitiveness.

Creation of new markets for farm products will occur with costlier fossil fuel prices if agriculture is a competitive supplier of energy or sequesterer of carbon. Costlier fossil fuels will create demand for non-fossil fuel energy. If corn ethanol, soy biodiesel or biomass for generating electricity or biofuels are low-cost sources of this energy, or if policy is adopted that makes them low-cost sources, then demand for agricultural products will increase.

Being an alternative supplier of energy or carbon dramatically lowers the downside to agriculture if biotechnology leads to innovations that increase crop yields faster than world food demand. Rather than having once again to face a future with falling real prices, agricultural prices instead will reflect the value of land as a supplier of energy or carbon. What this value will be depends on the market price of energy and carbon offsets, but a future backstopped by energy prices is brighter than one that is backstopped only by world food demand. If the recent slowdown in agricultural productivity continues for the next 20 or 30 years, then agriculture will not be a low-cost supplier of energy and carbon because its value in food production will be so high.

Concerns about expected increases in energy prices and other agricultural input costs have led some to oppose U.S. greenhouse gas (GHG) cap and trade legislative proposals. However, these policies could result in significant revenue for U.S. agriculture, which is a potential source of low-carbon bioenergy and low-cost abatement alternatives to fossil fuel emission reductions (i.e., offsets) through terrestrial sequestration, afforestation, and reductions in nitrous oxide and methane emissions. Previous studies of the impacts of low-carbon policies on the agricultural sector have generally not accounted for changes in production practices, demand responses, land use competition, or commodity market and offset revenues. This study is an attempt to simultaneously model all potential cost and revenue implications of low-carbon policies using a detailed economic model of the U.S. forest and agricultural sectors. We find higher input costs, higher output prices, modest consumer responses, increased bioenergy supply, and offset income opportunities. On net, we find that the U.S. agricultural sector would benefit from U.S. GHG mitigation efforts.

This study projects how meeting several proposed energy/climate change policy scenarios might impact the U.S. agricultural sector. For the purposes of each scenario studied, it is assumed that the Renewable Fuels Standard (RFS) established by the Energy Independence and Security Act of 2007 is in play. Along with the RFS, policy scenarios that have been analyzed include a cap and trade regulatory system and varying treatments of agricultural offsets.

The study looks at a "baseline" policy scenario, which is an extension of the USDA agricultural baseline through 2030. Four other scenarios are then compared with the Baseline Scenario. Among the other four scenarios is one in which emissions, including those from the agricultural sector, are regulated by the EPA in accordance with a 2007 Supreme Court ruling holding the agency responsible for regulating greenhouse gas (GHG) emissions under the Clean Air Act (EPA-Led Scenario). No legislative guidance is presumed for this scenario.

The following are key findings of the study.

Under a properly constructed cap-and trade-program:

• Net returns to agriculture are projected to be positive–including up to $13 billion annually in additional revenues for agriculture and forestry–and exceed baseline projections for eight of nine crops analyzed;
• Income from offsets and from market revenues is higher than any potential increase in input cost including energy and fertilizer;
• At projected carbon prices of up to $27 per metric tons CO2 equivalent (MtCO2e), afforestation of cropland will not occur;
• Major shifts in commodity cropland use do not occur;
• Demand for bioenergy feedstocks will cause significant shifts to hay and dedicated energy crop acreage from pasture conversion;
• Crop and beef prices are not disrupted; and
• Biomass feedstock production creates significant direct and indirect reduction in GHG. This includes a direct reduction of an accumulated 460 million MtCO2e.

If emissions are regulated by EPA without the benefit of multiple offsets:

• net farm income is projected to fall below baseline projections;
• agriculture is subjected to higher input costs with no opportunity to be compensated for the GHG reduction services the sector provides;
• impacts to beef production are uncertain; and
• if afforestation and grassland sequestration are the only offsets allowed and carbon prices are as high as $160 per MtCO2e, 60 million acres of cropland could be converted to forests and grasslands.

Three recent reports have estimated the market impacts of domestic offset programs, including afforestation, contained in the American Clean Energy and Security Act (ACES). The magnitude of these estimated impacts motivates this study. We show that with carbon prices as low as $30 per metric ton, a significant number of U.S. crop acres would be used to grow trees and this would cause price increases for some U.S. commodities. Although we present only one carbon price scenario, the modeling approach that we use suggests that the acreage and price impacts we describe here would increase at higher carbon prices.

This presentation gives an overview of some of the major challenges in predicting climate change. Among these are how global climate change will play out at regional scales, the challenge of predicting clouds and precipitation, and ways in which land use interacts with climate.

Each of these topics not only presents a scientific challenge but also is essential to planning and adaptation for practical issues such as agriculture and water resources. The presentation will discuss the current state of knowledge of each of these problems, including gaps in our knowledge and how climate scientists are working to fill these gaps.

Average annual temperature in the Midwest has risen much less than global average temperature over the past few decades. Observations show much of the average temperature increase is from minimum temperature increase, and the smaller trend of average temperature in the Midwest compared to surrounding regions is explained by neutral to cooling trend in summer maximum temperature. Two related but different questions are examined in light of these trends:

• Are recent Midwest temperature trends in contradiction with expectations from global warming theory?
• Can recent trends be attributed to specific mechanisms of temperature variability?

Climate simulations are used to isolate the effects of climate warming from natural variability. These simulations indicate the pattern of relatively small trend of maximum summer temperature is not inconsistent with global warming. Thus, recent trends do not contradict global warming expectations.

Three mechanisms of summer temperature variability will be described: spring soil moisture levels, Pacific Ocean surface temperature pattern, and subtropical Atlantic atmospheric moisture. Of these factors, current understanding of the effects of global warming suggest global warming might influence summer maximum temperature trend by causing an increase of subtropical Atlantic atmospheric moisture.

Future research directions that connect crop yield to climate drivers via attribution methods may improve projections and predictions of crop yields. In particular, attribution methods taken from atmospheric prediction studies may be extended to determine the likelihood of increased yield trend in the 1990s and 2000s in the absence of particular climate drivers. In addition, further refinement of predictability of climate drivers may lead to improvements in seasonal to decadal climate outlooks pertinent to crop yields.

This talk presents new directions that are emerging for forecasting changes in climate. Chief among these are ensemble simulation and forecasting for 10 to 20 years into the future. Ensemble simulation involves multiple simulations of climate that differ in one or more influential factors, such as the computer model used or the initial state of the climate system at the start of the forecast. These differences allow assessment of the unpredictable part of climate simulation and thus provide a measure of the uncertainty in a forecast. Forecasting decades into the future is still in an early phase of exploratory research. Nonetheless, advances in our understanding of periodic behaviors in the climate system, such as El Nino, have allowed initial efforts to show some tantalizing results, while also showing that there is considerable room for further improvement.

Entomology, as a field of study, remains the premier example of applied biology. As the most abundant class of animals on Earth, insects are not only fascinating creatures for study, but they also influence the quality and sustainability of human, animal, and plant life. They are vectors of diseases of man, livestock, and crops and pollinators of fruits and vegetables. They are pests that devour food, fiber plants, and grower livelihoods. They are ideal built-in indicators of biodiversity and global climate change.

Insect development is controlled by a physiological clock that is driven by accumulated heat units and by genetic code. Both mechanisms govern an insect’s response to climate change.

As we study insects and climate change, we must distinguish between acute (short-term) and chronic (long-term) changes. Acute changes will occur as insects respond to increasing temperatures allowing them to expand their normal range northward. Such an occurrence could become permanent immediately or could be in flux for a few years, until stabilizing as a chronic range expansion. Similar responses to changes in relative humidity, rain, wind, and light (cloud cover) most likely will occur.

Warmer temperatures will have their biggest acute effect on the life-cycle biology of an insect, primarily through shortening the time from egg hatch to adult egg-laying. This can have several ramifications, including increased generations per year and de-synchronization with food plants. We can estimate some direct effects; however, the likely disruption of multiple ecological interactions will undoubtedly create large ripple effects that are difficult to predict.

Pest insects are very plastic to immediate environmental conditions. They can move to “new hosts” or they can disperse to new areas where climes are more hospitable. Pest insects tend to be generalists and thus will be better buffered against environmental changes. Insects that are biological control agents, however, are often more specialized and thus vulnerable to predicted climate change. Such insects depend on a specific host insect being present at the right moment as a food source. Thus, as pests adjust to climate change, their natural control agents are likely to decline or become less effective.

Additional examples/scenarios will be presented as we discuss insects’ response to climate change.

Points for Discussion

1. Insects move on wind currents. How will changing wind currents, directional and velocity, affect insects?
2. As cropping systems and landscapes change, how will insect dynamics be influenced?
3. Will trophic interactions between insects, hosts, and the environment drastically change, and if so, how?
4. How do we predict chronic changes in insect behavior, biology, and population dynamics?
5. Will climate change create new pests or favor a resurgence of former pests to pest status?

The changes in climate predicted to take place over the next 30 to 50 years will impact the development and productivity of the crops we now grow for grain and biomass. An increase in atmospheric CO2 concentration, a rise in average air temperature, and more erratic and intensive precipitation are the major changes expected. These climate changes could produce some positive effects for crop production, but the net impact of climate change on agriculture (in the Midwest at least) is expected to be negative. The vegetative and reproductive structures of all plants exhibit temperature optima for growth. Higher average temperature will hasten phenological development. This could be positive for taking advantage of areas with limited soil moisture. But a shorter reproductive period will limit seed formation and development, higher night-time temperature will increase respiratory losses from both vegetative and reproductive tissues, and temperature extremes will disrupt metabolism at all stages of development. As a result, higher temperatures will generally lead to decreased grain and biomass yields.

Response to increasing atmospheric CO2 concentration, on the other hand, is expected to be positive for at least two reasons. First, photosynthesis rates of most C3 plants like soybean and wheat are limited by the CO2 concentration in the atmosphere. And second, stomatal apertures (pores in the leaf surface that allow gas exchange with the air) tend to close at higher CO2 concentration. This slows water loss from the leaves and increases the amount of biomass (or grain) produced per unit of water lost (i.e. water use efficiency-WUE). C4 plants, like corn and miscanthus, which already are fairly efficient water users, will not benefit nearly as much from the increase in atmospheric CO2. This differential response will most likely lead to a re-distribution of agricultural crops and changes in species ‘demographics’ with natural systems in the long term.

Other responses to elevated atmospheric CO2, such as a decrease in RuBP carboxylase production (the enzyme the ultimately fixed CO2 into a stable product plants use for growth), and a change in plant morphology that favor storage over assimilate will ultimately limit the benefit for grain and biomass production. More erratic and intensive precipitation will make crop management and genetic advances in crop performance much more challenging. Although today’s crop plants have been selected for high levels of productivity and average grain yields continue to increase under favorable conditions, the basic “conservative nature” of plants to limit seed formation and development under adverse conditions has not changed in concert. The redundant physiological mechanisms in place that ultimately lead to abortion of newly formed kernels when a drought coincides with flowering, for example, ensure that the primary outcome is successful development of a ‘few good seeds’ rather than many hundreds of seeds as required for a profitable harvest. Nonetheless, there is considerable excitement in the seed industry which is utilizing transgenic approaches to overcome these limitations by improving general drought tolerance of the crop.

The expectation is a doubling of current yields (for corn at least) within the next 20 years. This will be a remarkable accomplishment considering the redundant physiological mechanisms involved and the erratic changes in climate that are anticipated. Much greater effort is needed on understanding the basic genetic and physiological regulation of plant responses to climate change to achieve this lofty goal. Equally important is the need to recognize that environmental conditions during reproductive development directly impact the ‘quality’ of the harvested grain. Legume seeds, for example, are valuable because they accumulate large amounts of protein and oil. Small grains are valued for their starch content and quality. Higher temperatures during grain filling can affect protein content in small grains, oil content and fatty acid profiles in legumes dramatically. A resurgent wine industry in the Midwest also could be affected by a changing climate that impacts fruit development and quality. And the capacity of plants to withstand pathogen attack and accumulation of compounds such as aflatoxin in the grain is compromised by high temperatures or drought. The underlying mechanisms regulating this plant-microbe interaction are largely unknown; improved resistance to Aspergillus infection has come primarily from exotic germplasm.

The integrated response of plants to an impending drought provides some insight into how the scientific and agronomic communities need to address the complex interactions between the soil, plant, and atmosphere as the climate continues to change. Roots in the upper layers of the soil are the first to “experience” the drying soil conditions. Although most of the roots at this point are in the deeper soils layers and fully capable of keeping the aerial parts of the plant well hydrated, the roots in the dryer soil send a chemical signal to the leaves to ‘slow down’ water loss and close the stomatal pores through which CO2 and water vapor must pass. This is a system-wide response that integrates the physical nature of the soil, the biological capacity of the plants, and the overriding demand of the atmosphere. A similar approach is needed to integrate the impending climate constraints with the current and future genetic potential for energy transduction and storage, expanding knowledge of ecological nutrient cycles, and the overriding need to ensure farm-gate profits. Incorporating highly productive biomass generators like Miscanthus into current agricultural production systems has a number of advantages in terms of efficient land use, production of renewable energy, and carbon sequestration in C-depleted soils.

Biomass production models can provide timely and insightful information about deployment strategies, expectations for the future as climate continues to change, and rational approaches for genetic modification to enhance energy capture, C-sequestration, ecosystem services, and others. An integrated systems approach is essential to identify and address current knowledge gaps regarding carbon cycling and harvesting efficiency, best practices to convert row-crop area and uncultivated land to bioenergy crops, and evaluate the impact of management practices such as fertilization. Likewise, there are large knowledge gaps in our understanding of how best to modify biomass crops to balance the need for energy and sustainability. Genetic modifications that decrease C and N allocation to roots, for example, could increase biomass yield, but at the expense of soil organic C. Likewise, genetic modifications that generate readily decomposable plant biomass could accelerate decomposition by soil microbes and limit the potential for C-sequestration. Resolving these complex and interrelated issues requires the integration of many disciplines within CALS and across campus. Ideally, research programs that integrate plant genetics, whole plant physiology, soil science, microbiology, modeling and engineering, and atmospheric sciences need to be established and supported.

The production of livestock generates greenhouse gas (GHG) emissions, including carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). When animals respire, they produce CO2. Methane is produced during enteric fermentation in the animal’s digestive tract and is released into the atmosphere. Manure can produce CO2, N2O, and CH4 from microbial activity during storage and following land application.

The contribution of livestock production to GHG emissions has been estimated and reported by various groups. The estimated magnitude of GHG emission contributed by livestock production varies by how the estimates are made (i.e., which gases and source types are considered), and with the spatial area being considered in the estimates (i.e., for a specific region, country, or for the entire world). The FAO report, Livestock’s Long Shadow, a life-cycle assessment of the global environmental impact of livestock production, estimates that livestock production is responsible for 18% of all anthropogenic GHG emissions in the world (FAO, et al., 2007). This report considers emissions of CO2, N2O, and CH4 from enteric fermentation, manure management, land application of manure, and also from deforestation that the FAO associates with livestock production in developing countries. In contrast, the contribution from livestock production to GHG emissions in the form of CH4 and N2O in the Unites States from enteric fermentation and manure management has been estimated to be less than 3% of the total anthropogenic GHG emissions by the U.S. EPA (U.S. EPA, 2009). The 2007 U.S. EPA GHG emissions inventory estimates that U.S. agriculture is responsible for 5.8% of the total U.S. anthropogenic GHG emissions. Agricultural soil management is by far the largest contributor to agricultural GHG emissions, representing approximately 50% of the agricultural GHG emissions. The U.S. EPA inventory includes emissions from both commercial fertilizer and manure application in the agricultural soil management category. Enteric fermentation represents the second largest agricultural GHG emissions source, accounting for 34% of the agricultural emissions. Manure management is the third largest agricultural GHG emissions source, representing 14% of the GHG emissions from agriculture.

Emissions of GHG from manure storage, treatment, and land application are generated by microbial activity. Emissions of CH4 occur under anaerobic conditions, while N2O emissions occur when alternating aerobic and anaerobic conditions exist. This presentation considers animal housing, manure storage, manure treatment, and manure land application as sources of GHG emissions from livestock production. To reduce the uncertainty of GHG emissions inventories, additional and higher-quality GHG emissions data are needed. Additionally, more data on the impact of different manure storage, treatment, and land application systems are needed to better identify potential GHG mitigation opportunities related to manure management. Additional manure management emissions data is especially needed for N2O.

In addition to improved GHG emissions data for inventory purposes, research to identify practical and cost effective GHG mitigation options is also needed. While it is recognized that some current manure best management practices (such as biofilters for odor control, vegetated treatment systems for manure run-off control, and permeable manure storage covers) may actually increase GHG emissions associated with manure management systems, and other best management practices (such as sub-surface manure injection) can decrease GHG emissions, the overall potential of these systems to impact GHG emissions from animal agriculture has not been well- defined at this time.

In this presentation, we will discuss the expected impacts of global warming on issues related to animal health and wellbeing. Factors that will be included in the discussion will be the possible effect of climate change on metabolic diseases, infectious diseases, animal welfare, and nutrition. Similarities and differences with predicted impacts of global warming on human health will also be discussed.

Climate change legislation could have profound impacts on the livestock industry. Proposed legislation does not impose greenhouse gas (GHG) emissions limits on agriculture, but would allow agriculture to participate in the GHG “cap and trade” program. The direct GHG emissions from livestock are the second largest source of agricultural GHG, and these emissions could be used to create offsets for the cap and trade program. This presentation will concentrate on expected adjustments in the livestock industry as energy, feed, and carbon prices change under the proposed legislation.