scientists agree the major driver behind therise in global greenhouse gas emissions is human activity. how does farming fit it and,whatis the contribution of animal agriculture and how are these values calculated? the consuming public is more and more interestedin where their food comes from, whatâ€™s the carbon footprint.whatâ€™s the carbon footprint, or the whatâ€™s the environmental footprint, of a gallon ofmilk, or a pound of beef, or a pound of chicken meat?we want to look at the greenhouse gasses coming off the farm and how we can change strategies. my name is david schmidt and iâ€™m an agriculturalengineer at the university of minnesota and
regional coordinator for for the nationalproject, animal agriculture in a changing climate. there is a significant amount ofmiscommunication about the role of agriculture in climate change. some say that animal agricultureis the largest contributor to greenhouse gas emissions while others deny any contributionfrom animals. the answer lies somewhere in between. the objective of this video is toprovide you with a solid foundation of how emission estimates are calculated and thereal contributions of animal agriculture to us and global ghg emissions. carbon is all around us. it is the fourthmost abundant chemical element in the universe, behind hydrogen, helium and oxygen.the biggest reservoir of carbon is stored
in rocks- approximately 66,000 gigatons withone gigaton is equal to 1 trillion kilograms. the second biggest reservoir is the deep ocean,and the third largest reservoir is in fossil fuels. the atmosphere and the surface oceanare the smallest carbon reservoirs but possibly the most important. carbon is moving betweenthese reservoirs constantly because of a variety of chemical and biological processes. thisis known as the carbon cycle. the total amount of carbon that cycles inand out of the atmosphere naturally each year is about 210 gigatons. the arrows and yellownumbers indicate this movement, or cycling of carbon. plants and oceans are referredto as net carbon â€œsinksâ€ because they absorb more carbon from the atmosphere thanthey emit. these carbon emissions occur in
the form of plant respiration and chemicalexchanges with the ocean. the red numbers indicate the human influencein the cycle, also known as â€œanthropogenic emissions.â€ they can be mostly be attributedto the burning of fossil fuels and changes in land use. human activities contribute ninegigatons of carbon emissions annually. about two gigatons of that carbon gets taken upor absorbed by the ocean. three gigatons of that carbon gets absorbed by plants throughphotosynthesis and taken up in plant soil system. all this movement results in an annualnet increase of about four gigatons of carbon going into the atmosphere each year. as you can see in this diagram, the amountof carbon dioxide in the atmosphere was relatively
stable for hundreds of thousands of years,at an average of around 230 parts per million. then about 100 years ago, the co2 concentrationin the atmosphere began climbing to where it is right now, about 400 parts per million. this animated diagram more dramatically illustratesthe rise in carbon dioxide levels in the earthâ€™s atmosphere in more recent years, since 1979.the numbers on the left and right indicate the co2 concentration in parts per million.again this indicates the current co2 level reaching up to and even beyond 400 parts permillion. while we do not intend to focus on all ofthe greenhouse gases in this lesson, it is important to note that carbon dioxide is notthe only greenhouse gas. the most common greenhouse
gas is water vapor, followed by carbon dioxide, methane , nitrous oxide and fluorinated gasses. excluding water vapor, the combinedsources of carbon dioxide, primarily from fossil fuel use and land use change, makeup about 77% of the global greenhouse gasses. because these other gasses trap differentamounts of energy per molecule of gas, scientists have normalized the data into something calledcarbon dioxide equivalents, or co2 equivalents. this â€œequivalentâ€ refers to the equivalentheating potential of the gas. this is also known as radiative forcing or global warmingpotential. for instance, a single molecule of methane will trap approximately 25 timesthe amount of energy as will a single molecule of carbon dioxide. so methane has a co2 equivalentof 25. nitrous oxide has a co2 equivalent
of 298. this use of co2 equivalents allowsus to evaluate the impact of the gasses on the environment - not just the amount of thesegasses in the atmosphere. anthropogenic greenhouse gases are emittedby many sources and from every country. together these nations contribute a world total of45 thousand million metric tons of co2 equivalents. this graph shows percentages of greenhousegas emissions by country in 2012. the united states is currently the second highest emitterof these gases, contributing about 15% of the world total. the highest emitting countryis china. however, this same information can be evaluated based on emissions per capita.this breakdown shows the us at about 19 tons co2e per year per person vs china at 7.5 tonsco2e per year per person.
taking a closer look at the sources of greenhousegas emissions in the united states alone by economic sector,, we see that agriculturecontributes 9 percent of total emissions in the us. total emissions in the us add up toapproximately 6,673 million metric tons of co2 equivalents. agricultureâ€™s 9% representsabout 515 million metric tons of that amount. looking at the agricultural sector itself,we can see that agricultural soil management is the biggest source, it accounts for about50% of total agricultural emissions. this is followed by enteric fermentation at about32% and manure management at 15%. now looking at the type of gases emitted,about 55% of the agricultural emissions are from nitrous oxide, which is produced naturallythrough the the microbial process of nitrification
and denitrification of mineral nitrogen inthe soil. the remaining 45% is from enteric methane or from methane formed during themicrobial breakdown of manure. note that these emissions are only the direct emissions ofgreenhouse gasses occurring on the farm. other emissions that would occur off farm - likeemissions from fertilizer production or electricity used on the farm are not included in thesenumbers. we can also look more closely at emissionsfrom animal species. in this chart you can see the comparisons between beef cattle, dairycattle, swine, poultry and all other livestock. these differences are primarily a functionof total animal numbers and the contribution of enteric fermentation. again these are directemissions for animal production and do not
include emissions from the production of thingslike animal feed. overall if you look at all animals in theunited states for example â€“ the beef sector would have the greatest impact on carbon footprintof this nation but thatâ€™s only because there are so much more beef animals than dairy animals.we have 90 million beef animals and 9 million dairy animals, so 10 times more beef animals. however, a better way to think about greenhousegas emissions is in terms of emissions per unit of production. we can look at kilogramsof co2 equivalents per kilogram of product produced or product consumed. this evaluationincludes not only direct emissions from the farm, but also the emissions that occur afterthe products leave the farm. we will discuss
this further a little later in the video.thisgraph compares the greenhouse gas emissions of several products on per kilogram basis.of all the products, lamb is the highest emitter per kilogram of product consumed, and beefis the second highest emitter at 27 kilograms of co2 equivalents per kilogram of beef consumed.dairy is much lower in emissions, with 1.9 kilograms of co2 equivalents per kilogramof milk consumed. before getting further into attributing emissionsto different sectors of animal agriculture or to different sources on the farm, weâ€™lllook at the system used to measure and calculate these emissions.there is a way to quantify greenhouse gasses. this quantification method is called lca,life cycle assessment. it has been done for
many years and it has been done by many differentgroups using different methodologies. the life cycle assessment, or lca, is an accountingmethod that tracks all of the greenhouse gas emissions produced by a given process, productor system. often this is called a â€˜cradle to graveâ€™ analysis, because it encompassesall of the emissions in the life cycle of the process, product or system being analyzed.this includes anything from the extraction of raw materials to the final disposal ofthe end product. animal scientists, engineers and others canfurther describe the scope and mission of the lca as it relates to animal agriculture. basically, the life cycle assessment looksat the entire life cycle associated with a
product. letâ€™s say if mcdonalds or walmartor some other chain were to ask me whatâ€™s the carbon footprint or whatâ€™s the environmentalfootprint of a gallon of milk or a pound of beef or a pound of chicken meat produced byyour company. most producers would have no idea â€“ buta life cycle assessment allows you to do just that. it allows you to look at the entire life cycleimpact of that product. for example, the carbon footprint of a gallon of milk includes notjust enteric gasses that come out the front end of the cow or methane or other gassesthat come off the manure, it includes everything â€“ the herbicides and other chemicals appliedto crops, the crops themselves, the soils
where the crops are grown, the animals, whetherit is enteric gasses or manure gases, it includes the cooling of the product, the transportof product and so on. everything from cradle to grave of this product. the true life cycleof this product. life cycle assessment is a systematic approachfor primarily accounting for environmental impacts. it is a systems scale analysis ofany product or service really. in the dairy industry. what it means is to divide the systeminto supply chain stages, typically. in each of those stages we would have what we callunit processes that have material and energy flows, inputs and outputs from other unitprocesses as well as, inputs or outputs from nature. so emission to the soil, water, orair. and the process of lca looks from cradle
to grave. dr. thomaâ€™s analysis in 2013 of greenhousegas emissions from the production of milk in the united states looked at the entirelife cycle of the milk supply chain, starting with the production of fertilizer to growfeed for cows through the consumption of milk and disposal of milk packaging. so if we are talking about just the dairyfarm so that would be what we might consider a gate to gate analysis and we would be interestedin what happens just on the farm â€“ that would not be considered a full life cycleassessment. so, when we did the carbon footprint for milk, we literally had to account forthe coal, the transportation of the coal,
the construction of the power plant, the lossesin the transmission lines to run the refrigeration units at the retail. so all of that is accountedfor. this table from thomaâ€™s lca shows the breakdownof greenhouse gas emissions across the milk production supply chain. the colors representthe four different types of gas emitted by each stage in the cycle, from feeding thecows, enteric fermentation, manure management ... all the way through the consumption ofmilk and disposal of packaging. the pie chart further illustrates the percentage of eachactivityâ€™s contribution to milkâ€™s carbon footprint. thomaâ€™s analysis found that the co2 equivalentsproduced by each kilogram of milk consumed
ranged from 1.77 to 2.4. this is about 17.6pounds of co2 equivalents per gallon of milk consumed.72 percent of those emissions occurred before the milk left the farm gate.so from the extraction of coal, say, for the electricity that may be used anywhere in thesupply chain all the way to the emissions associated with wastewater treatment for wastedmilk that goes down the drain or the plastic container that ends up in the landfill andmay generate methane. so all of those emissions across the entire supply chain are, we attemptto account for â€“ tally them up then say this is the impact. thoma applied the same system to an analysisof of greenhouse gas emissions from pork production.
this study took into account all of the activitiesin the pork supply chain that contribute to emissions, from electricity and fuel to manureand waste, across all stages of production, from the sow barn to the consumption of thepork products produced. the lca showed co2 equivalents at an averageof 8.8 to 11.6 kilograms of co2 equivalents per kilogram of pork, from production to consumption.this can also be calculated as 2.2 to 2.9 pounds of co2 equivalents per 4 ounce servingof pork. approximately 60% of the emissions occurred before the product left the farmgate. while the lca is widely accepted as the mostuseful and accurate tool for estimating a farm operationâ€™s environmental impact, thereis some interest in learning about farm specific
variables that might affect the results. dodifferences in farm size, manure handling, farm practices and technologies, soil conditions,regional climate systems and other farm factors impact the emissions? when we looked at this in various ways. . . . whatwasnâ€™t clear was â€“ oh small farms were not as good as big farms. we saw small farmsthat were down in the 0.8 0.9 range. we saw large farms that were in the 1.7 1.8. ourconclusion from that was â€“ it is not what you are managing but how you are managingit so the implementation of best or beneficial management practices and care of the animals,care in the ration formulation, all of these things contribute to the better performingfarms.
dr. thomaâ€™s lca for pork production foundsome effect from manure management. farms using anaerobic lagoons had slightly higheremissions than those using deep pit systems. as noted in the thoma report, a full lca encompassesmany variables, and with each variable there are some assumptions to be made. how was theelectricity used on the farm produced? was it coal based or nuclear? was the corn grownfor feed irrigated? if so, what energy source powered the pumps? what was the animal diet?how many piglets per sow? how far away is the slaughter plant? the consumer market?was the meat cooked on a gas stove or electric stove? how much of the final product was wasted- either in cooking or off the plate? all of these variables must be assessed and generalizedfor this kind of study.
scan level lcaâ€™s are used to help pinpointthe main emission areas of a product or process. for swine production, about 23% of the emissionsare at the consumer level and 62% on the farm level. these farm level emissions are splitprimarily between manure management and feed production. this information helps the industryand individual producers target any emission reduction strategies. helping farms perform better is the ultimategoal of the lca. international standards have been developed for conducting an lca, whichis important so that farmers, regulators and others can get a clear picture of farm productemissions and identify what could be done to reduce these emissions.
once you know what the lca impact is of yourproduct then you really know where you are â€“ if you feel your too high then you cancompare to what it would be if you were to make changes â€“ so that you can reduce. but if you donâ€™t know where you are, youhave no idea whether changes would work. that is why it is so critical to have good assessmentmethods, because they help you to know where you are. the analogy is - you driving on theinterstate â€“ with a car that doesnâ€™t have an odometer. you have no clue how fast youare going but you see speed limits everywhere. so you have no clue â€“ am i going to fast?you know, what am i doing here? thatâ€™s where the industry is right now. there are regulations,some of them very strict â€“ for example in
california, yet the producers donâ€™t knowâ€“ am i complying am i not complying? where shall i go? where is the goal pole? they donâ€™tknow, thatâ€™s a situation that is untenable. and the public is exerting extensive pressure,the legislature is, regulatory agencies are. there is nothing simple or straight forwardabout tracking greenhouse gas emissions and global carbon cycling. it is also clear that no process or productis entirely responsible for these emissions. it is a combination of both natural and humanactivity that can be evaluated on a global scale or on an individual product scale. we are all aware of the value of agricultureas we look forward to the challenges of feeding
an every growing human population. however,we must also understand for our role in the production of greenhouse gas emissions. thanks for learning about this important topic.