Climate Change and Carbon Sequestration

8/9/2019 Climate Change and Carbon Sequestration

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IntroductionThe Earths average surface temperatureincreased 1.3 degrees Fahrenheit over thepast century, and is projected by the Inter-governmental Panel on Climate Change toincrease by an additional 3.2 to 7.2 degreesover the 21st century (IPCC, 2007a). Theseseemingly slight changes in temperaturecould have profound implications for farm-ers and ranchers. According to the Envi-ronmental Protection Agency, an increasein average temperature can:

lengthen the growing season inregions with relatively cool spring

and fall seasons;adversely affect crops in regionswhere summer heat already limitsproduction;

increase soil evaporation rates; and

increase the chances of severedroughts (2008a).

Innovative farming practices such as conser-vation tillage, organic production, improvedcropping systems, land restoration, land use

A Publication of ATTRANational Sustainable Agriculture Information Service 1-800-346-9140 www.attra.ncat.org

ATTRANational Sustainable

Agriculture Information Service

(www.ncat.attra.org) is managed

by the National Center for Appro-

priate Technology (NCAT) and is

funded under a grant from the

United States Department of

Agricultures Rural Business-

Cooperative Service. Visit the

NCAT Web site (www.ncat.org/

sarc_current.php) for

more information on

our sustainable agri-

culture projects.

Agriculture, Climate Changeand Carbon Sequestration

By Jeff Schahczenskiand Holly Hill

NCAT Program

Specialists

2009 NCAT

Table of Contents

Introduction ............................1

Climate change science......2

How does climate changeinfluence agriculture? .........3

How does agricultureinfluence climatechange? ....................................3

Agricultures rolein mitigating climatechange ......................................6

The value of soil carbon:Potential benefits foragriculture ...............................8

Charge systems:Carbon tax ...............................8

Cap and trade: A privatemarket for greenhousegas emissions .........................9

Subsidizing positivebehavior .................................12

Summary ................................13

References .............................14

Resources ...............................14

Appendix:How to get involvedin voluntary privatecarbon markets ....................15

Carbon sequestration and reductions in greenhouse gas emissions can occur through a variety ofagriculture practices. This publication provides an overview of the relationship between agriculture,

climate change and carbon sequestration. It also investigates possible options for farmers and ranchers

to have a positive impact on the changing climate and presents opportunities for becoming involved

in the emerging carbon market.

An organic wheat grass field. Growing research is showing that organic production systems are one of the most

climate-friendly systems of food production.
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Page 2 ATTRA Agriculture, Climate Change and Carbon Sequestration

change and irrigation and water manage-ment, are ways that farmers can addressclimate change. Good management prac-tices have multiple benefits that may alsoenhance profitability, improve farm energyefficiency and boost air and soil quality.

Climate change science

Natural shifts in global temperatures haveoccurred throughout human history. The20th century, however, has seen a rapid risein global temperatures. Scientists attributethe temp increase to a rise in carbon diox-ide and other greenhouse gases releasedfrom the burning of fossil fuels, deforesta-tion, agriculture and other industrial pro-cesses. Scientists refer to this phenomenonas the enhanced greenhouse effect.

The naturally occurring greenhouse effect

traps the heat of the sun before it canbe released back into space. This allowsthe Earths surface to remain warm and

habitable. Increased levels of greenhousegases enhance the naturally occurringgreenhouse effect by trapping even more ofthe suns heat, resulting in a global warm-ing effect. Figure 1 illustrates the naturaland enhanced greenhouse effects (Pew Cen-ter on Global Climate Change, 2008).

The primary greenhouse gases associated

with agriculture are carbon dioxide (CO2),methane (CH

4) and nitrous oxide (N

20).

Although carbon dioxide is the most prev-alent greenhouse gas in the atmosphere,nitrous oxide and methane have longerdurations in the atmosphere and absorbmore long-wave radiation. Therefore, smallquantities of methane and nitrous oxide canhave significant effects on climate change.

Several excellent resources and fact sheetsexplain the greenhouse effect and the

science behind climate change. See theResources section for information on howto obtain copies.

Figure 1. The Greenhouse EffectSource: The National Academy of Sciences. www.climatechange.ca.gov/publications/faqs.html

Natural Greenhouse EffectThe greenhouse effect is a natural warm-

ing process. Carbon dioxide (CO2) and cer-

tain other gases are always present in the

atmosphere. These gases create a warm-ing effect that has some similarity to the

warming inside a greenhouse, hence the

name greenhouse effect.

Enhanced Greenhouse EffectIncreasing the amount of greenhouse gases

intensifies the greenhouse effect. This side

of the globe simulates conditions today,

roughly two centuries after the IndustrialRevolution began.

Conservation Tillage

Pursuing Conservation

Tillage Systems

for Organic Crop

Production

Energy Saving Tips

for Irrigators

Anaerobic Digestion

of Animal Wastes:

Factors to Consider

Biodiesel:

The Sustainability

Dimensions

Ethanol Opportunities

and Questions

Renewable Energy

Opportunities on

the Farm

Federal Resources for

Sustainable Farming

and Ranching

Related ATTRAPublications

Illustration of the greenhouse effect (courtesy of the Marion Koshland Science Museum of the National Academy of

Sciences). Visible sunlight passes through the atmosphere without being absorbed. Some of the sunlight striking the

earth (1) is absorbed and converted to heat, which warms the surface. The surface (2) emits infrared radiation to the

atmosphere, where some of it (3) is absorbed by greenhouse gases and (4) re-emitted toward the surface; some of

the heat is not trapped by greenhouse gases and (5) escapes into space. Human activities that emit additional green-

house gases to the atmosphere (6) increase the amount of infrared radiation that gets absorbed before escaping into

space, thus enhancing the greenhouse effect and amplifying the warming of the earth.
http://www.climatechange.ca.gov/publications/faqs.htmlhttp://www.climatechange.ca.gov/publications/faqs.html


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Page 3ATTRAwww.attra.ncat.org

How does climate changeinfluence agriculture?Climate change may have beneficial as well

as detrimental consequences for agricul-ture. Some research indicates that warmertemperatures lengthen growing seasons andincreased carbon dioxide in the air resultsin higher yields from some crops. A warm-ing climate and decreasing soil moisture canalso result in production patterns shiftingnorthward and an increasing need for irri-gation. Changes, however, will likely varysignificantly by region. Geography will playa large role in how agriculture might benefitfrom climate change. While projections lookfavorable for some areas, the potential ofincreased climate variability and extremesare not necessarily considered. Benefits toagriculture might be offset by an increased

likelihood of heat waves, drought, severethunderstorms and tornadoes. An increasein climate variability makes adaptation dif-ficult for farmers.

The U.S. Department of Agriculturereleased a report in May 2008 that focused

on the effects of climate on agriculture,specifically on cropping systems, pastureand grazing lands and animal management

(Backlund et al., 2008). The following find-ings are excerpted from the report:

With increased carbon dioxide andhigher temperatures, the li fe cycleof grain and oilseed crops will likelyprogress more rapidly.

The marketable yield of many hor-ticultural crops, such as tomatoes,onions and fruits, is very likely tobe more sensitive to climate change

than grain and oilseed crops.

Climate change is likely to lead to a

northern migration of weeds. Manyweeds respond more positively toincreasing carbon dioxide than most

cash crops.

Disease pressure on crops and domes-tic animals will likely increase withearlier springs and warmer winters.

Projected increases in temperature anda lengthening of the growing season

will likely extend forage productioninto late fall and early spring.

Climate change-induced shifts inplant species are already under wayin rangelands. The establishmentof perennial herbaceous species isreducing soil water availability earlyin the growing season.

Higher temperatures will very likelyreduce livestock production duringthe summer season, but these losseswill be partially offset by warmertemperatures during the winterseason (Backlund et al., 2008).

How does agricultureinfluence climate change?

Agricultures contribution togreenhouse gas emissionsAgriculture activities serve as both sourcesand sinks for greenhouse gases. Agriculturesinks of greenhouse gases are reservoirs ofcarbon that have been removed from theatmosphere through the process of biologi-cal carbon sequestration.

The primary sources of greenhouse gases inagriculture are the production of nitrogen-based fertilizers; the combustion of fossil fuels

such as coal, gasoline, diesel fuel and naturalgas; and waste management. Livestock entericfermentation, or the fermentation that takesplace in the digestive systems of ruminantanimals, results in methane emissions.

Carbon dioxide is removed from the atmo-sphere and converted to organic carbonthrough the process of photosynthesis. Asorganic carbon decomposes, it is convertedback to carbon dioxide through the process

of respiration. Conservation ti llage, organic

production, cover cropping and crop rota-tions can drastically increase the amount ofcarbon stored in soils.

In 2005, agriculture accounted for from10 to 12 percent of total global human-caused emissions of greenhouse gases,according the Intergovernmental Panel onClimate Change (IPCC, 2007b). In theUnited States, greenhouse gas emissions

C

onserva-

tion tillage,

organicproduction, cover

cropping and crop

rotations can dras-

tically increase the

amount of carbon

stored in soils.
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from agriculture account for 8 percentof all emissions and have increasedsince 1990 (Congressional ResearchService, 2008). Figure 2 presents recentdata in carbon dioxide equivalents (CO

2e).

Greenhouse gases have varying globalwarming potentials, therefore climatescientists use carbon dioxide equivalentsto calculate a universal measurement ofgreenhouse gas emissions.

Figure 2. Greenhouse gas emissions and carbon sinks in agricultural activities, 1990-2005 (CO2

equivalent).

Source 1990 1995 2000 2005Avg.

2001-2005

million metric tons CO2

equivalent (MMTCO2-Eq)

U.S. Agricultural Activities

GHG Emissions (CH4

and N2O)

Agriculture Soil Managementa 366.9 353.4 376.8 365.1 370.9

Enteric Fermentationb 115.7 120.6 113.5 112.1 115.0

Manure management 39.5 44.1 48.3 50.8 45.6

Rice Cultivation 7.1 7.6 7.5 6.9 7.4

Agricultural Residue Burning 1.1 1.1 1.3 1.4 1.2

Subtotal 530.3 526.8 547.4 536.3 540.1Carbon Sinks

Agricultural Soils (33.9) (30.1) (29.3) (32.4) (31.7)

Other na na na na na

Subtotal (33.9) (30.1) (29.3) (32.4) (31.7)

Net Emissions, Agriculture 496.4 496.7 518.1 503.9 508.4

Attributable CO2

emissions:cFossil fuel/mobile combustion

46.8 57.3 50.9 45.5 52.6

% All Emissions, Agricultured 8.5% 8.0% 7.7% 7.4% 8.0%

% Total Sinks, Agriculture 4.8% 3.6% 3.9% 3.9% 4.0%

% Total Emissions, Forestry 0.2% 0.2% 0.2% 0.3% 0.3%

% Total Sinks, Forestrye 94.3% 92.0% 94.8% 94.7% 95.0%

Total GHG Emissions, All Sectors 6,242.0 6,571.0 7,147.2 7,260.4 6,787.1

Total Carbon SInks, All Sectors (712.8) (828.8) (756.7) (828.5) (801.0)

Net Emissions, All Sectors 5,529.2 5,742.2 6,390.5 6,431.9 5,986.1

Source: EPA, Inventory of U.S. Grenhouse Gas Emissions and Sinks: 1990-2005, April 2007, [http://epa.gov/climatechange/emissions/

usinventoryreport.html]. Table ES-2, Table 2-13, Table 6-1, Table 7-1, and Table 7-3. EPA data are reported i teragrams (tg.), which are equivalent to

one million metric tons each.

a. N2O emissions from soil management and nutrient/chemical applications on croplands.

b. CH4

emissions from ruminant livestock.

c. Emissions from fossil fuel/mobile combustion associated with energy use in the U.S. agriculture sector (excluded from EPAs reported GHG

emissions for agricultural activities).

d. Does not include attributable CO2

emissions from fossil fuel/mobile combustion.

e. Change in forest stocks and carbon uptake from urban trees and landfilled yard trimmings.
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Figure 3 illustrates agricultural greenhouse gasemissions by source in the United States.

The following is evident from the informa-tion in Figures 2 and 3:

Despite some improvement incertain areas since 1990, theU.S. agricultural production sec-tor increased its greenhouse gasemissions and expanded its role inclimate change.

The U.S. agricultural productionsector is a net emitter of green-

house gas emissions. That is,agricultural production annuallycreates more greenhouse gas emis-

sions than it captures, despite thepotential for the sector to seques-ter higher levels of carbon withmanagement changes.

The U.S. agricultural productionsector contributes more greenhousegas emissions from methane (CH

4)

and nitrous oxide (N2O) than from

carbon dioxide (CO2).

Agricultural soil management isthe single greatest contributor togreenhouse gas emissions from the

U.S agricultural production sector.Enteric fermentation (flatulenceand belches of ruminants) andmanure management are also largecontributors.

Carbon sequestrationCarbon sequestration in the agriculture sec-

tor refers to the capacity of agriculture landsand forests to remove carbon dioxide fromthe atmosphere. Carbon dioxide is absorbedby trees, plants and crops through photo-synthesis and stored as carbon in biomassin tree trunks, branches, foliage and rootsand soils (EPA, 2008b). Forests and stable

grasslands are referred to as carbon sinksbecause they can store large amounts ofcarbon in their vegetation and root systemsfor long periods of time. Soils are the larg-

est terrestrial sink for carbon on the planet.The ability of agriculture lands to store orsequester carbon depends on several fac-tors, including climate, soil type, type ofcrop or vegetation cover and managementpractices.

The amount of carbon stored in soil organicmatter is influenced by the addition of car-bon from dead plant material and carbonlosses from respiration, the decompositionprocess and both natural and human dis-

turbance of the soil. By employing farmingpractices that involve minimal disturbanceof the soil and encourage carbon sequestra-tion, farmers may be able to slow or evenreverse the loss of carbon from their fields.In the United States, forest and croplandscurrently sequester the equivalent of 12percent of U.S. carbon dioxide emissionsfrom the energy, transportation and indus-trial sectors (EPA, 2008b).

Figure 3. Agricultural greenhouse gas emissions, average from 2001 to 2005. Source: EPA, 2007Inventory report, April 2007. www.epa.gov/climatechange/emissions/usinventoryreport.html

f

rb

management

management

c

smanagement

1.

2.

3.

4.

5.

6.

1.2.

3.

4.

5.

6.
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Figure 4, adapted from the EPA, illustrates

the different processes through which trees

and soils can gain and lose carbon.

Agricultures role in

mitigating climate changeSeveral farming practices and technolo-

gies can reduce greenhouse gas emissions

and prevent climate change by enhancing

carbon storage in soils; preserving existing

soil carbon; and reducing carbon dioxide,

methane and nitrous oxide emissions.

Conservation tillage and

cover cropsConservation tillage refers to a number

of strategies and techniques for establish-ing crops in the residue of previous crops,which are purposely left on the soil surface.

Reducing tillage reduces soil disturbanceand helps mitigate the release of soil car-bon into the atmosphere. Conservation till-age also improves the carbon sequestration

capacity of the soil. Additional benefits ofconservation tillage include improved water

conservation, reduced soil erosion, reduced

Atmospheric carbon is fixed by trees and

other vegetation through photosynthesis.

Carbon is lost back to the atmosphere

through respiration and decompositon

of organic matter.

Aboveground carbon:

Stem

Branches

Foliage

Carbon is lost to the

atmosphere through

soil respiration.

Fallen leaves and

branches add

carbon to soils.

Some carbon is transferred from

belowground carbon (for example,

root mortality) to the soils.

Belowground carbon:

Roots

Litter

Some carbon is internally

transferred from aboveground

to belowground carbon soils.

Soil carbon:

Organic

Inorganic

Figure 4. Carbon pools in forestry and agriculture. Source: EPA. www.epa.gov/sequestration/local_scale.html
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fuel consumption, reduced compaction,increased planting and harvesting flexibility,reduced labor requirements and improvedsoil tilth. For further information, see theATTRA publication Conservation Tillage.

Improved cropping andorganic systems

Recent reports have investigated the potentialof organic agriculture to reduce greenhousegas emissions (Rodale Institute, 2008).Organic systems of production increase soilorganic matter levels through the use of com-posted animal manures and cover crops.Organic cropping systems also eliminate theemissions from the production and transpor-tation of synthetic fertilizers. Components oforganic agriculture could be implementedwith other sustainable farming systems,such as conservation tillage, to furtherincrease climate change mitigation poten-tial. See the ATTRA publication PursuingConservation Tillage Systems for Organic CropProduction for more information.

Generally, conservation farming prac-tices that conserve moisture, improve yieldpotential and reduce erosion and fuel costsalso increase soil carbon. Examples of prac-tices that reduce carbon dioxide emissionsand increase soil carbon include directseeding, field windbreaks, rotational graz-ing, perennial forage crops, reduced sum-mer fallow and proper straw management(Alberta Agriculture and Rural Develop-ment, 2000). Using higher-yielding cropsor varieties and maximizing yield potentialcan also increase soil carbon.

Land restoration andland use changesLand restoration and land use changes

that encourage the conservation andimprovement of soil, water and air qual-ity typically reduce greenhouse gas emis-sions. Modifications to grazing practices,such as implementing sustainable stockingrates, rotational grazing and seasonal useof rangeland, can lead to greenhouse gasreductions. Converting marginal croplandto trees or grass maximizes carbon storageon land that is less suitable for crops.

Irrigation and watermanagementImprovements in water use efficiency,through measures such as irr igation systemmechanical improvements coupled with areduction in operating hours; drip irr iga-tion technologies; and center-pivot irriga-

tion systems, can signifi

cantly reduce theamount of water and nitrogen applied tothe cropping system. This reduces green-house emissions of nitrous oxide and waterwithdrawals. For more information, see theATTRA publication Energy Saving Tipsfor Irrigators.

Nitrogen use effi ciencyImproving fertilizer efficiency throughpractices like precision farming using GPS

tracking can reduce nitrous oxide emis-sions. Other strategies include the use ofcover crops and manures (both green andanimal); nitrogen-fixing crop rotations;composting and compost teas; and inte-grated pest management. The ATTRA FarmEnergy Web site contains information aboutreducing nitrogen fertilizer on the farm atthe following link: www.attra.ncat.org/farm_energy/nitrogen.html.

Methane captureLarge emissions of methane and nitrousoxide are attributable to livestock wastetreatment, especially in dairies. Agriculturemethane collection and combustion systemsinclude covered lagoons and complete mixand plug flow digesters. Anaerobic digestionconverts animal waste to energy by captur-ing methane and preventing it from beingreleased into the atmosphere. The captured

methane can be used to fuel a variety ofon-farm applications, as well as to gener-ate electricity. Additional benefits includereducing odors from livestock manureand reducing labor costs associated withmanure removal. For more information onanaerobic digestion, see the ATTRA publi-cationAnaerobic Digestion of Animal Wastes:Factors to Consider.

C

onservation

farming

practicesthat conserve

moisture, improve

yield potential and

reduce erosion

and fuel costs also

increase soil carbon.
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BiofuelsThere is significant scientific controversyregarding whether biofuels particularlythose derived from oilseeds (biodiesel),feed corn (ethanol) or even from cellulosicsources are carbon neutral. To ascer-tain the true climate neutrality of biofuelsrequires a careful life-cycle analysis of the

specific biofuel under consideration. Also,an analysis is needed to understand whatthe global land use change implications wil lbe if farmers grow more of a specific biofuelfeedstock. For further information on biofu-

els, see the ATTRA publications Biodiesel:The Sustainability Dimensions and EthanolOpportunities and Questions.

Other renewable energy optionsRenewable energy opportunities such as

wind and solar also present significantopportunities for the agriculture sector toreduce greenhouse gas emissions. For fur-ther information about these options, seethe ATTRA publication Renewable EnergyOpportunities on the Farm.

The value of soil carbon:Potential benefits foragriculture

As Mazza (2007) has remarked, creatingfarm and forestry systems with strong incen-tives for growing soil carbon could well beat the center of climate stabilization.

Thus, a new crop that farmers and ranchersmay grow in the future is carbon. The NaturalResources Conservation Service, part of theUSDA, has long been a promoter of managingcarbon in efforts to improve soil quality.

As with any crop, farmers and ranchers

need a market for this new crop, as wellas a price that will make it more profit-able to grow. From a broader social con-text, the questions of who will purchasethis new crop and what is a fair price arealso of private and public importance. Vol-untary private carbon markets exist in theUnited States. Federal government marketsare expected to be created soon. How tovalue carbon from the perspective of the

individual farmer and rancher, as well associety at large, is the heart of understand-ing the role agriculture can play in carbonsequestration and climate stabilization.

The two most frequently discussed systemsto create value for offsetting greenhouse gasemissions are known as carbon taxation andcap and trade. Government subsidies are dis-

cussed less often, but will also play a role ingreenhouse gas emission reductions.

Charge systems: Carbon taxBy taxing every ton of carbon in fossil fuelsor every ton of greenhouse gas companiesemit, entities that emit greenhouse gases oruse carbon-based fuels will have an incen-tive to switch to alternative renewable fuels,invest in technology changes to use carbon-based fuels more efficiently and in generaladopt practices that would lower their level ofgreenhouse gas emissions. Thus a carbon or

greenhouse gas emission tax values carbonin negative terms of tax avoidance. Thosefarms and ranches that emit or use less car-bon-intensive fuels pay a smaller tax.

From the perspective of farmers and ranch-ers, a carbon tax would increase the directand indirect costs of agricultural production.Farmers and ranchers use carbon-based

fuels directly in the forms of petroleum andnatural gas and indirectly in the forms ofcarbon-based fertilizers and pesticides andfuel-intensive inputs. Thus, a carbon taxcould move farmers and ranchers to shift tosystems of production that either eliminatethe use of fossil fuels and inputs or at leastimprove the efficiency of their use.

However, proponents of carbon taxes havegenerally sought to exclude the agriculturesector from such taxation. For the most

part, carbon tax proponents have beenmore interested in placing greenhouse gasemission taxes on upstream producers ofthe original source products. This includescoal, petroleum and natural gas produc-ers and major emitters such as large elec-tric utilities. Nonetheless, as people workto reduce greenhouse gas emissions, thepotential to place a carbon tax on sectorslike agriculture may become more likely.

C

reating farm

and forestry

systems withstrong incentives for

growing soil carbon

could well be at the

center of climate

stabilization.

(Mazza, 2007)


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Benefits of a carbon tax forfarmers and ranchersA major benefit of a carbon or greenhousegas emission tax would be the creation of astream of tax revenue that the governmentcould use to further induce the practiceand technology changes necessary to lowergreenhouse gas emissions. For example,many of the current agriculture conserva-tion programs, such as the EnvironmentalQuality Incentive Program and the newerConservation Stewardship Program, sup-port improvements in soil quality and couldbe funded in part from emission or carbontaxes, thereby providing a revenue sourceto subsidize those who adopt or maintainemission-reduction practices or carbonsequestration activities. See the ATTRApublication Federal Resources for Sustain-

able Farming and Ranchingfor more infor-mation. Tax revenues could also assist inthe support of conservation programs likethe Conservation Reserve Program, whichworks to keep sensitive and highly erodiblelands out of production since these landssequester soil carbon.

Another benefit of this approach is that atax provides a clear and stable cost to cur-rent practices. A tax also makes it easierto determine changes that will be moreprofitable in a new cost environment. Forinstance, if a concentrated animal feedingoperation understood the cost of their emis-sions as expressed by their emission tax, itwould be easier for the operation to deter-mine alternatives to current practices thatwould be cost efficient. At a high enough taxrate, installing methane digesters to lowergreenhouse gas emission would becomeeconomically feasible.

Finally, it has been argued that a carbontax approach is cost effective in imple-mentation, at least when compared to thecap-and-trade method of achieving green-house gas emissions reductions. As recentCongressional Budget Office report states:available research suggests that in the nearterm, the net benefits (benefits minus costs)of a tax could be roughly five times greater

than the net benefits of an inflexible cap(Congressional Budget Office, 2008).

Downside of a carbon taxThe introduction of any tax results in dis-cussions of where the burden of taxationlies and issues of equity. In short, taxationis about who pays and who does not. New

taxes also often result in a public discus-sion of the fairness of the tax. There is logicto the argument that the burden of a car-bon or greenhouse gas emission tax shouldbe placed first and foremost on those whoeither create carbon-intensive fuels or those

who are the largest emitters of greenhousegases. The greatest source of greenhousegas emissions in the United States is thecombustion of fossil fuels. Since agricultureuses a small percentage of U.S. fossil fuels,

an argument can be made that the burdenof taxation should not to fall on this sector.Still, agriculture is heavily dependent onfossil fuels and any carbon or greenhousegas emission tax would likely be costly.

The ability of any individual farmer orrancher to pass on the increased costs offossil fuels that this kind of taxation wouldcreate is much more limited than in othersectors of the economy. For instance, if acarbon tax is placed on diesel fuel, diesel

fuel manufacturers can more easily pass onthe tax burden to the consumers of the die-

sel. The ability to pass on costs to consum-ers is greater in industries where there islittle product substitution and where a fewproducers dominate the market. This is not

the case for farmers and ranchers, giventheir relative lack of market concentrationand power.

Cap and trade: A private market

for greenhouse gas emissionsA government-sponsored cap-and-trade sys-tem would create a new market for green-house gas emissions by creating a new prop-erty right the r ight to emit.

The market is created by a governmentthat sets a limit or cap on total greenhousegas emissions allowed. Companies that

A

tax provides

a clear and

stable costto current practices.


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emit greenhouse gases are issued emissionpermits that allow a certain amount of emis-sions. Companies and groups that exceedtheir allowed emissions must purchase off-sets from other entities that pollute less thantheir allowance or from entities that seques-ter carbon.

These exchangeable emission permits, often

called allowances, are measured in tons ofcarbon dioxide equivalents per year. Carbon

dioxide equivalents provide a common mea-sure for all greenhouse gas emissions and arecalculated by converting greenhouse gasesinto carbon dioxide equivalents according totheir global warming potential.

Over time, the government will continu-ally lower the total level of allowances tomeet an established level of acceptabletotal emissions. As the supply of allow-

ances decreases, the value of the allow-ances will rise or fall depending on demandand on the ability of emitters to make nec-essary changes to reduce emissions or

purchase offsets from groups more capable ofreducing emissions.

Benefits for farmers andranchersDepending on the practices adopted,farmers and ranchers could be a sourceof inexpensive carbon reduction and cap-ture the value of these allowances as off-sets. In short, the value of offsets wouldbecome the market price of carbon equiva-lents. This would become the value of thenew crop carbon that farmers andranchers could grow.

From the May 26, 2008 issue of HighCountry News:

For example, if a farmer shifted to anorganic system of production, measurable

improvements in the ability of the farmer tosequester carbon could be verified and thefarmer could sell this sequestered carbon atthe current carbon market price set in thenew emissions market (Ogburn, 2008).

Figure 5. Chicago Climate Exchange daily report. Source: Chicago Climate Exchange. www.chicagoclimateexchange.com
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A limited, privately created and voluntarycap-and-trade system called the ChicagoClimate Exchange (CCX) has been in oper-

ation in the United States since 2003. Theemission cap is set by emitting entities thatvoluntarily sought to limit greenhouse gasemissions. Purchases of agriculture off-sets have been part of this exchange. As

can be seen from Figure 5, the price of car-bon dioxide equivalents per ton has variedsignificantly over the life of the exchangeand hit its highest level in 2008 at $7.35per ton. This price has not yet resulted inan overwhelming participation by farmersand ranchers.

Downsides of cap and tradeFor farmers and ranchers to provide carbonoffsets for greenhouse gas emitters, farmers

and ranchers must be willing to make long-term, or even permanent, changes in notonly practices but perhaps whole systemsof production. These changes also need toprovide verifiable changes that result in trueoffsets of greenhouse gas emissions. Theissues of verifiability, permanence and whatis known as additionalityare critical to thesuccess of agricultures role in the cap-and-

trade system and the ultimate reduction ofgreenhouse gas emissions.

Verifiability is critical because the systemor practice change must result in a measur-

able change in the amount of carbon stored.For example, the adoption of a no-tillcultivation practice is thought to result insoil with higher carbon sequestration capac-ity. However, there is continuing scientificdebate over whether the practice of contin-uous no-till does in fact lead to long-termadditional storage of carbon in the soil(Baker et al., 2007).

The CCX divided the United States intozones and allocated specific levels of car-bon sequestration to each acre farmed ina particular zone under continuous no-tillpractices, as illustrated in Figure 6.

While there may be some need to sim-plify the implementation of a nationwidesoil carbon sequestration project relatedto tillage practice change, it is very

doubtful that the actual carbon storage levelsallocated can be achieved across areas thatare so large. Finally, the CCX does notverify the actual carbon storage as a resultof the practice change, but only monitorsthat the practice is maintained during thelife of the contract. Thus, it is doubtful thecarbon offset truly matches actual carbonsequestered.

The issue of permanence is also critical.What happens after a farmer or rancherchanges to a practice or system of produc-tion, is paid for carbon stored and thendecides to change practices and potential lyrelease the carbon that he or she was paidto sequester to offset emissions?

Additionality refers to the issue that afarmer or rancher can only offer and bepaid for an offset for a new sequestration

of carbon, not for a practice or a system ofproduction already in place. For instance,if a rancher developed a permanent windshelter belt, that change in land use wouldlikely result in new, or additional, car-bon sequestration. However, a rancherwho already developed a similar shel-ter belt would not be eligible for an offsetbecause the rancher would not be providingadditional carbon sequestration. Likewise,

Figure 6. Conservation tillage soil offset map. Source: Chicago ClimateExchange. www.chicagoclimateexchange.com
http://www.attra.ncat.org/http://www.chicagoclimateexchange.com/http://www.chicagoclimateexchange.com/http://www.attra.ncat.org/


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a farmer already engaged in conservationtil lage would not provide additional carbonstorage by maintaining that practice.However, the current USDA ConservationStewardship Program provides a possiblepayment structure that pays farmers tomaintain practices.

Additionality is also important because

of the possibility that perverse incentivesmay be created that encourage farmers orranchers to release carbon so that they canget paid to store it. For example, a farmerpracticing no-till farming may decide toabandon the practice because of the newavailability of per-acre payments and switchback to no-till at a later time. To addressthis and stop additional greenhouse gasemissions, the idea of offsets would needto be expanded to include farmers and

ranchers already undertaking a practice orspecific land use that stores soil carbon.

Subsidizing positive behaviorA final mechanism that could expandthe ability of the agriculture sector to

mitigate greenhouse gas emissions is one

that is already well known a direct sub-

sidy. Many federal conservation programs

provide incentives, known as cost shares,

that help farmers and ranchers make

changes in practices to conserve natural

resources. For more information, see the

ATTRA publication Federal Resources for

Sustainable Farming and Ranching. Forexample, data in Figure 7, adapted from

a Natural Resources Conservation Service

bulletin, indicates various crop and animal

management practices that can either lower

greenhouse gas emissions or increase car-

bon sequestration. Under the Conservation

Stewardship Program and the Environmen-

tal Quality Incentive Program, farmers and

ranchers can receive incentives to adopt

new practices or receive support to main-tain such practices. Though not designed

to address climate change issues specifi-

cally, many federal conservation programs

already provide public incentives to reduce

greenhouse gas emissions.

Conservation Practice GHG Objectives Additional Benefits

CROPSConservation tillage and reducedfield pass intensity

Sequestration, emission reduction Improves soil, water and air quality.Reduces soil erosion and fuel use

Effi cient nutrient management Sequestration, emission reduction Improves water quality. Savesexpenses, time and labor.

Crop diversity through rotations andcover crops

Sequestration Reduces erosion and water require-ments. Improves soil and water quality.

ANIMALS

Manure management Emission reduction On-farm sources of biogas fuel and

possibly electricity for large opera-tions, provides nutrients for crops.

Rotational grazing and improvedforage

Sequestration, emission reduction Reduces water requirements. Helpswithstand drought. Increases long-term grassland productivity.

Feed management Emission reduction Reduces quantity of nutrients.Improves water quality. Moreeffi cient use of feed.

Figure 7. Agricultural practices and benefits. Source: NRCS.http://soils.usda.gov/survey/global_climate_change.html
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In the future, conservation programs couldbe refocused to lower greenhouse emissionsor increase carbon sequestration. Perhapsmodifications of the Conservation Steward-ship Program and the Environmental Qual-

ity Incentive Program could allow for lon-ger contracts (currently a maximum offiveyears) so that outcomes are reached and

maintained. Also, the programs could addspecific validation procedures to assure cli-mate targets are met and sustained.

Benefits of subsidiesThere is an immediate benefit to farmersand ranchers willing to make changes thatmeet the challenges of climate stabilization.If sufficiently funded with outreach andtechnical assistance, efforts can be madeto assure that all farmers and ranchers

regardless of their situation take advan-tage of these programs. Final ly, resourcescan be prioritized to different regions of thecountry or to specific practices or systems ofproduction so programs can be cost-effec-tive in reaching climate change goals.

Downside of subsidiesSubsidies are a public cost, and this is a con-siderable downside. Furthermore, subsidies

are based on the idea that the governmentcan know and assure that the practices itpays for achieve the intended outcomes. Forexample, the federal government providessignificant subsidization of corn ethanol pro-

duction. Many argue that this changed theprice offield corn and increased costs forpeople who use corn as animal feed andfor other countries that import corn to feedpeople. There are also questions about howsubsidies can reduce greenhouse gas emis-sions. Will subsidizing a shift to a continuousno-till cultivation operation result in greatercarbon sequestration? If the scientific under-standing of the relationship between carbonsequestration and no-till is simply in error,then public dollars spent to change farmerbehavior would be wasted. Furthermore, willsubsidization offer the least expensive way toachieve a specific outcome?

Paustian et al. (2006) estimated that it wouldtake a price of at least $13 per ton of car-bon dioxide equivalent ($50 per ton of car-bon) per year to offset 70 million metric tons(MMT) of carbon dioxide equivalents. Thiswould be a total public cost of close to $1billion dollars per year for perhaps as longas 40 years. Also, this represents an offset of

only 4 percent of total U.S. greenhouse gasemissions in 2004. Is this the least expen-sive way to reduce greenhouse gas emissions

compared to alternative public expenditures?For instance, what if public dollars were com-mitted to a research program to improve thegas mileage of automobiles?

Finally, how do we know that Paustian et. al.are correct in their estimation of the incen-tive needed to change farming and ranch-ing practices? Recently, Sperow (2007) esti-

mated an average cost to sequester carbon at$261 per ton of carbon. This is considerablyhigher than the Paustian estimate. Whilethe difference between these studies canbe explained by the fact that there is a wideregional variation in carbon sequestrationcapacity and how sequestration is accom-plished, public costs would nonetheless besignificant to achieve greenhouse gas emis-sion reductions through subsidization.

SummaryThe public sector will play an important role

in determining how to engage the agricul-ture sector in the reduction of greenhousegas emissions. The government can use itspower to tax, subsidize or create a new mar-

ket mechanism to do this. In 2008, the U.S.

Senate debated climate change legislation,including the Lieberman-Warner bill. Thisbill proposes a modified cap-and-trade sys-tem with the expectation that the agriculture

sector will provide at least 15 percent of theoffsets needed to reduce greenhouse gasemissions 71 percent from 2005 levels by2050. Whether this or future legislation will

become the base of future climate changeimprovements, there is little doubt that agri-culture will play some role in the effort.

T

he public

sector will

play animportant role in

determining how

to engage the agri-

culture sector in the

reduction of green-

house gas emissions.


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Environmental Protection Agency Global Warming

Impacts on Agriculture,http://epa.gov/climatechange/effects/agriculture.html

Pew Center on Global Climate Change,

www.pewclimate.org

Consortium for Agricultural Soil Mitigation

of Greenhouse Gases (CASMGS),

www.casmgs.colostate.eduClimate Friendly Farming, Washington State

University Center for Sustaining Agriculture

and Natural Resources, http://cff.wsu.edu

Pacific Northwest STEEP - Solutions to Environmental

and Economic Problems, http://pnwsteep.wsu.edu

ClimateandFarming.org,

www.climateandfarming.org

Soil Carbon Center at Kansas State University,

www.soilcarboncenter.k-state.edu

ReportsHarnessing Farms and Forests in the Low-Carbon

Economy: How to Create, Measure, and Verify

Greenhouse Gas Offsets. The Nicholas Institute

for Environmental Policy Solutions. Edited by

Zach Willey & Bill Chameides, Environmental

Defense. Duke University Press. Durham &

London. 2007

Addressing Climate Change and Providing New

Opportunities for Farmers. Institute for Agri-culture and Trade Policy. Mark Muller, Cath-

erine Hofman, Paul Hodges. September 2000.

www.iatp.org/iatp/publications.cfm?accountID=258&refID=29793

Agriculture and Climate Change: Greenhouse GasMitigation Opportunities and the 2007 Farm

Bill. Evan Branosky and Suzie Greenhalgh.

World Resources Institute Policy Note. March2007.http://pdf.wri.org/agricultureandghgmitigation.pdf

Soil Carbon Sequestration in Agriculture: Farm

Management Practices Can Affect Greenhouse

Gas Emissions. Dept. of Land Resources andEnvironmental Sciences, Montana State

University Extension Service. Perry Miller,Rick Engel, and Ross Bricklemyer.

http://msuextension.org/publications/AgandNaturalResources/MT200404AG.pdf

Using Agricultural Land for Carbon Sequestration.Purdue University. Andrea S. Bongen.

www.agry.purdue.edu/soils/Csequest.PDF

Contracting for Soil Carbon Credits: Design and Costs

of Measurement and Monitoring. Departmentof Agricultural Economics and Economics,Montana State University Department of Soil

and Crop Sciences and Natural ResourceEcology Laboratory, Colorado State University.

May 2002. Sin Mooney, John Antle,

Susan Capalbo, and Keith Paustian

www.climate.montana.edu/pdf/mooney.pdf

Multiple Benefits of Carbon-Friendly AgriculturalPractices: Empirical Assessment of

Conservation Tillage. Center for Agricultural

and Rural Development, Iowa State University.Lyubov A. Kurkalova, Catherine L. Kling,

Jinhua Zhao. February 2003. www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdf

How to get involved in voluntary

private carbon marketsThe future of the voluntary carbon market remainsto be seen. Currently, farmer payments from carbonoffsets alone are not substantial enough to rationalizedecisions for land management changes. However, itis important that the farm sector be included in solu-tions for mitigating climate change. Before enroll-ing in any type of carbon credit program, however, itis important to understand eligibility requirements,

contract expectations and verification policies. Review

all of these items with carbon aggregators before decid-

ing to enroll.

Eligibility

The following table was developed by the National Farm-

ers Union Carbon Credit Program to help farmers deter-

mine eligibility for enrollment in specific projects (Farmers

Union, 2008). Different aggregators might have different

requirements for eligibility, enrollment and contracts.

Appendix
http://www.attra.ncat.org/http://epa.gov/climatechange/effects/agriculture.htmlhttp://epa.gov/climatechange/effects/agriculture.htmlhttp://epa.gov/climatechange/effects/agriculture.htmlhttp://www.pewclimate.org/http://www.casmgs.colostate.edu/http://cff.wsu.edu/http://pnwsteep.wsu.edu/http://www.climateandfarming.org/http://www.soilcarboncenter.k-state.edu/http://www.iatp.org/iatp/publications.cfm?accountID=258&refID=29793http://www.iatp.org/iatp/publications.cfm?accountID=258&refID=29793http://pdf.wri.org/agricultureandghgmitigation.pdfhttp://pdf.wri.org/agricultureandghgmitigation.pdfhttp://pdf.wri.org/agricultureandghgmitigation.pdfhttp://msuextension.org/publications/AgandNaturalResources/MT200404AG.pdfhttp://msuextension.org/publications/AgandNaturalResources/MT200404AG.pdfhttp://www.agry.purdue.edu/soils/Csequest.PDFhttp://www.climate.montana.edu/pdf/mooney.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.card.iastate.edu/publications/DBS/PDFFiles/03wp326.pdfhttp://www.climate.montana.edu/pdf/mooney.pdfhttp://www.agry.purdue.edu/soils/Csequest.PDFhttp://msuextension.org/publications/AgandNaturalResources/MT200404AG.pdfhttp://msuextension.org/publications/AgandNaturalResources/MT200404AG.pdfhttp://pdf.wri.org/agricultureandghgmitigation.pdfhttp://pdf.wri.org/agricultureandghgmitigation.pdfhttp://www.iatp.org/iatp/publications.cfm?accountID=258&refID=29793http://www.iatp.org/iatp/publications.cfm?accountID=258&refID=29793http://www.soilcarboncenter.k-state.edu/http://www.climateandfarming.org/http://pnwsteep.wsu.edu/http://cff.wsu.edu/http://www.casmgs.colostate.edu/http://www.pewclimate.org/http://epa.gov/climatechange/effects/agriculture.htmlhttp://epa.gov/climatechange/effects/agriculture.htmlhttp://www.attra.ncat.org/


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Page 16 ATTRA

Agriculture, Climate Change and

Carbon Sequestration

By Jeff Schahczenski and Holly Hill

NCAT Program Specialists

2008 NCAT

Holly Michels, Editor

Amy Smith, Production

This publication is available on the Web at:

www.attra.ncat.org/attra-pub/carbonsequestration.htmlorwww.attra.ncat.org/attra-pub/PDF/carbonsequestration.pdf

IP338

Slot 336

Version 012309

Eligible land and credit-earning potential

No-till: Carbon credits are issued at the rate of 0.2 to 0.6

metric tons of carbon per acre annually to participants who

commit to continuous conservation tillage on enrolled land

for at least five future years. In most cases, credit can be

earned for the previous year. Enrolled acres may be planted

in low-residue crops, such as beans, peas and lentils, no

more than three of the contract years. Alfalfa or other hayed

forage will be considered as no-till for these contracts.

Seeded grass stands: Carbon credits are earned at a rate

of 0.4 metric tons to 1 metric ton per acre annually, even

if enrolled in Conservation Reserve Program. Grass stands

seeded prior to January 1, 1999, are not eligible for enroll-

ment in the program. Credits can be earned back to 2003

with proper documentation.

Native rangeland: Grassland with a formal grazing plan

may earn up to 0.52 tons per acre annually. Credits can be

earned back to 2003 with proper documentation.

Forestry: Trees planted after 1990 can earn carbon credits

annually, provided no harvest is intended.

Methane offset: Methane captured or destroyed can earncarbon credit. Animal waste systems, including anaero-

bic digesters and covered lagoons, can be enrolled. Each

ton of methane captured earns 21 tons of carbon credits

(Farmers Union, 2008).

A signed contract between the landowner and

the Chicago Climate Exchange or an aggrega-

tor for the ap propriate management practices

(Agricultural and Food Policy Center, 2008).

Contracts

Contracts are based on afive-year period for crop

production and rangeland projects. At the end of thecontract, producers are free to renew the contract for

another five years or let the contract expire. Once a

contract expires, landowners have no more obligations

to the CCX or to the aggregator. However, if a land-

owner discontinues the approved sequestration produc-

tion practice prior to the end of the contract, the CCX

or aggregator will ask the owner to return the amount

of carbon that would have been sequestered up to that

point or pay for the same amount of carbon at mar-ket price. Additionally, the project owner will not be

allowed to further participate in the CCX (Agricultural

and Food Policy Center, 2008).

Verification

Once a project is approved, the aggregator is responsible

for obtaining independent verification by an approved

verifier to ensure the actual greenhouse gas sequestra-

tion. A project is subject to initial and annual verification

for the duration of its contract with the Chicago Climate

Exchange (Chicago Climate Exchange, 2009).

Finding an aggregatorSeveral aggregators are located across the countryto help farmers and ranchers enroll in carbon offsetprojects. The following aggregators provide Web sites

with detailed information on contracts and enrollment.For a full list of carbon aggregators for the ChicagoClimate Exchange, visit their Web site at www.chicagoclimatex.com.

National Farmers Union Carbon CreditProgram, http://carboncredit.ndfu.org

National Carbon Offset Coalition,www.ncoc.us

Pacific Northwest Direct Seed Association,www.directseed.org/carbontrading.html

How to enrollYou will need to provide the following information toenroll in carbon sequestration programs:

Land maps to document ownership of a giventract of land, including the legal description ofthe tract.

Document of management practices, such asprogram forms for croplands, grass and forestmanagement.
http://www.chicagoclimatex.com/http://www.chicagoclimatex.com/http://carboncredit.ndfu.org/http://www.ncos.us/http://www.ncos.us/http://www.directseed.org/carbontrading.htmlhttp://www.ncos.us/http://www.directseed.org/carbontrading.htmlhttp://carboncredit.ndfu.org/http://www.chicagoclimatex.com/http://www.chicagoclimatex.com/

Documents

Climate Change and Carbon Sequestration