Climate Change and Global Food Security - Section 1 ppt

Boutton and Shinichi Yamasaki Handbook of Photosynthesis, edited by Mohammad Pessarakli Chemical and Isotopic Groundwater Hydrology: The Applied Approach, Second Edition, Revised and Ex

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Preface

Anthropogenic perturbation of the global carbon cycle has increasedthe atmospheric concentration of carbon dioxide, and decreased thecarbon pool in the world’s agricultural soils Since the industrialrevolution, the atmospheric concentration of carbon dioxide hasincreased by about 30% from 280 parts per million by volume (ppmv)

to 370 ppmv This increase is attributed to emissions of carbon fromfossil fuel combustion estimated at 270 Pg (gigatons), and from landuse change and soil cultivation estimated at 136 Pg Conversion ofnatural to agricultural ecosystems, with attendant soil erosion andrapid mineralization of soil organic matter, has depleted the carbonpool by 66 to 90 Pg for global soils, and 3 to 5 Pg for soils in theUnited States Depletion of the soil organic carbon pool has adverseimpacts on soil quality leading to increase in risks of soil erosion,decline in aggregation and soil structure, reduction in plant avail-able water capacity, decline in activity and species diversity of soilfauna, and overall decline in agronomic/biomass productivity Thedecline in soil quality is more severe in soils of the tropics thantemperate regions, and in soils managed for low-input subsistencefarming than those under intensive commercial agriculture Soils

of Sub-Saharan Africa, Central and South Asia, and tropical

iv Climate Change and Global Food Security

America are severely depleted of their organic matter pool, prone

to degradation by erosion and other processes, do not respond toinputs, and have low productivity

The world population of 6.06 billion in 2000 will increase to 7.2billion in 2012, 8.3 billion in 2030, and 9.3 billion in 2050 Practicallyall the increase in the world population will occur in the developingcountries, where soils are severely depleted of their organic carbonpool and have low productivity The population of developing coun-tries will increase by 35% from 4.9 billion in 2000 to 6.6 billion in

2025 The required increase in cereal production by 2025 will be

778 million MT, an average of 31 million MT per year The requiredincrease in 2050 will be 1519 million MT, an average of 30 million

MT per year The required cereal production in developing countrieswill be more than double by 2050, mainly because of the projectedrapid increase in population The increase in food production willhave to come from increasing production per unit area from existingland, because there is little if any potential for bringing new landunder cultivation Therefore, restoring the quality of degraded soils

is essential, for which enhancing soil organic carbon pool is a cipal prerequisite

prin-Restoring the depleted organic carbon pool in soils of developingcountries of the tropics and subtropics is a challenging task forseveral reasons First, the resource poor farmers may not be able

to afford the inputs needed to attain the required increase in cropyield even if the inputs were made available Second, crop residuesand other bio-solids that must be returned to the soil are invariablyused for other purposes, such as household fuel, fodder, fencing andconstruction material, and so on Third, the decomposition rate oforganic matter may be four to five times higher in the tropics than

in temperate climates Thus, there is a need to develop appropriatefarming systems to cater to the multifaceted demands of theresource-poor small landholders of the tropics

Encouraging adoption of recommended management practicesfor enhancing the organic carbon pool is not a simple task for thesoils of temperate climates of the developed economies either There

is a strong need to provide incentives and commodify soil carbon,which can then be traded like any other farm commodity While theClean Development Mechanism (CDM) under the Kyoto Protocoland the BioCarbon Fund of the World Bank may be policy tools forproviding incentives to farmers of developing countries, interna-tional emissions trading joint implementation, among others, may

be useful tools for those in developed countries

2 Soil carbon dynamics under changing climate

3 The impact of changes in carbon dioxide and ecologicalenvironments on agronomic yields and food production invarious world regions

4 World food demands and supply during the 21st century

5 Policy and economic issues related to carbon trading andenhancing agricultural production

6 Research and development priorities for enhancing soilcarbon pool and food security

Contents

Preface iiiContributors xiii

Changing Times and Direction 39

Robert D Havener, Christopher R Dowswell, and

Norman E Borlaug

viii Climate Change and Global Food Security

Climate Change Effects on the Water Supply in Some

Major River Basins 147

Ranjan S Muttiah and Ralph A Wurbs

Chapter 7

Climate Change and Terrestrial Ecosystem Production 173

Wilfred M Post and Anthony W King

Chapter 8

The Changing Role of Forests in the Global Carbon Cycle:

Responding to Elevated Carbon Dioxide in

the Atmosphere 187

Evan H DeLucia, David J Moore, Jason G Hamilton,

Richard B Thomas, Clint J Springer, and Richard J Norby

Chapter 9

Impact of Climate Change on Soil Organic Matter

Status in Cattle Pastures in Western Brazilian Amazon 223

Carlos C Cerri, Martial Bernoux, Carlos E.P Cerri, and

Keith Paustian

Contents ix

Agronomic Production

Chapter 10

Climate Change, Agriculture, and Sustainability 243

Cynthia Rosenzweig and Daniel Hillel

Chapter 11

Assessing the Consequences of Climate Change for

Food Security: A View from the Intergovernmental

Panel on Climate Change 269

William Easterling

Chapter 12

Climate Change and Tropical Agriculture: Implications

for Social Vulnerability and Food Security 293

Hallie Eakin

Chapter 13

Effects of Global Climate Change on Agricultural Pests:

Possible Impacts and Dynamics at Population, Species

Interaction, and Community Levels 321

Anthony Joern, J David Logan, and William Wolesensky

Chapter 14

Food Security and Production in Dryland Regions 363

B.A Stewart

Chapter 15

Climate Change and Crop Production: Challenges to

Modeling Future Scenarios 383

Eugene S Takle and Zaitao Pan

x Climate Change and Global Food Security

Farming/Cropping Systems

Chapter 16

Soil Carbon Sequestration: Understanding and Predicting

Responses to Soil, Climate, and Management 407

James W Jones, Valerie Walen, Mamadou Doumbia, and

Arjan J Gijsman

Chapter 17

Reducing Greenhouse Warming Potential by Carbon

Sequestration in Soils: Opportunities, Limits,

and Tradeoffs 435

John M Duxbury

Chapter 18

Management Practices and Carbon Losses via

Sediment and Subsurface Flow 451

Lloyd B Owens and Martin J Shipitalo

Chapter 19

Measuring and Monitoring Soil Carbon Sequestration

at the Project Level 467

R César Izaurralde

Chapter 20

Dynamics of Carbon Sequestration in Various

Agroclimatic Zones of Uganda 501

Moses M Tenywa, Majaliwa Mwanjalolo,

Matthias K Magunda, Rattan Lal, and Godfrey Taulya

Chapter 21

Soil Carbon Sequestration in Dryland Farming Systems 515

Parviz Koohafkan, Ana Rey, and Jacques Antoine

Contents xi

Chapter 22

More Food, Less Poverty? The Potential Role of

Carbon Sequestration in Smallholder Farming

Systems in Senegal 539

Petra Tschakert

Chapter 23

Hillside Agriculture and Food Security in Mexico:

Advances in the Sustainable Hillside

Management Project 569

Jose I Cortés, Antonio Turrent, Prócoro Díaz,

Leobardo Jiménez, Ernesto Hernández, and Ricardo Mendoza

Chapter 24

Soil Organic Carbon, Quality Index, and Soil

Fertility in Hillside Agriculture 589

Jorge D Etchevers, Miguel A Vergara, Miguel M Acosta,

Carlos M Monreal, and Leobardo Jiménez

Chapter 25

Terrestrial Carbon Sequestration in Zambia 605

Robert B Dadson, Jagmohan Joshi, Fawzy M Hashem,

Arthur L Allen, Catherine S Bolek, Steven W Muliokela, and Albert Chalabesa

xii Climate Change and Global Food Security

Chapter 28

Policies and Incentive Mechanisms for the Permanent

Adoption of Agricultural Carbon Sequestration Practices

in Industrialized and Developing Countries 679

John M Antle and Linda M Young

Chapter 29

The Impact of Climate Change in a Developing Country:

A Case Study from Mali 703

Tanveer Butt and Bruce McCarl

Development Priorities

Chapter 30

Researchable Issues and Development Priorities for

Countering Climate Change 729

Rattan Lal, B.A Stewart, David O Hansen, and

Norman Uphoff

Economics and Economics

Montana State University

Bozeman, Montana

Jacques Antoine

Land and Soil Fertility Management ServiceFood and Agriculture Organization

Centro de Energia Nuclear na Agricultura

Universadade de São PauloSão Paulo, Brazil

xiv Climate Change and Global Food Security

Sasakawa Africa Association

International Maize and Wheat

Texas A&M University

College Station, Texas

Carlos C Cerri

Centro de Energia Nuclear na

Agricultura

Universidade de São Paulo

São Paulo, Brazil

Carlos E.P Cerri

Centro de Energia Nuclear na

Agricultura

Universidade de São Paulo

São Paulo, Brazil

Princess Anne, Maryland

Roy Darwin

U.S Department of Agriculture–Economic Research ServiceWashington, D.C

Prócoro Diaz

Instituto de Recursos NaturalesColegio de PostgraduadosMontecillo, México

México City, México

John M Duxbury

Department of Crop and Soil Science

Cornell UniversityIthaca, New York

The Ohio State UniversityColumbus, Ohio

Fawzy M Hashem

Department of AgricultureUniversity of MarylandEastern Shore

Princess Anne, Maryland

Daniel Hillel

Center for Climate Systems Research

Columbia UniversityNew York, New York

xvi Climate Change and Global Food Security

Environmental Science Division

Oak Ridge National

Rural Development Division

Food and Agriculture

School of Natural Resources

The Ohio State University

Texas A&M UniversityCollege Station, Texas

Ricardo Mendoza

Instituto de Socíoeconomía Estadística e InformáticaColegio de PostgraduadosCampus Pueblo, México

Majaliwa Mwanjalolo

Department of Soil ScienceMakerere UniversityKampala, Uganda

Contributors xvii

Richard J Norby

Environmental Science Division

Oak Ridge National

Department of Soil and Crop

Science and Natural Resource

Ecology Laboratory

Colorado State University

Fort Collins, Colorado

Wilfred M Post

Environmental Science Division

Oak Ridge National

G Edward Schuh

Hubert H Humphrey Institute

of Public AffairsMinneapolis, Minnesota

Shahla Shapouri

U.S Department of Agriculture–Economic Research ServiceWashington, D.C

Martin J Shipitalo

U.S Department of Agriculture–Agricultural Research Service

North Appalacian Experimental WatershedCoshocton, Ohio

Clint J Springer

Department of BiologyWest Virginia UniversityMorgantown, West Virginia

xviii Climate Change and Global Food Security

B.A Stewart

Dryland Agricultural Institute

West Texas A&M University

West Virginia University

Morgantown, West Virginia

Cornell UniversityIthaca, New York

Miguel A Vergara

Instituto de Recursos Naturales

Colegio de PostgraduadosMontecillo, México

Valerie Walen

Institute of Food and Agricultural SciencesUniversity of FloridaGainesville, Florida

William Wolesensky

Program in MathematicsCollege of St Mary’sOmaha, Nebraska

Ralph A Wurbs

Department of Civil Engineering

Texas A&M UniversityCollege Station, Texas

Linda M Young

Department of Agricultural Economics and EconomicsMontana State UniversityBozeman, Montana

Section I

Global Food Security

Agroecosystems 101.6 Adapting to Thermal Damage 101.7 Mitigation 121.7.1 High Carbon Sequestration Potential of

Tropical Agroecosystems 121.7.2 Carbon Sequestration by Smallholder

Farming Communities 151.8 Conclusion 16Acknowledgment 16References 16

4 Sanchez

Most of the world has witnessed dramatic increases in percapita food production over the last 30 years However, theopposite occurred in Sub-Saharan Africa Per capita food pro-duction in this region continues to decline, and hunger, largelydue to insufficient food production, affects about 200 millionpeople, 34% of the region’s population (Table 1.1) Projections

to 2015 suggest that hunger in Asia and Latin America islikely to decline with continued economic growth, while inAfrica it is likely to remain constant (Dixon et al., 2001) Thedifference is that enough food is produced in countries likeIndia and China Hunger in these nations is primarily caused

by unemployment and a corresponding lack of ating capacity Africa simply does not produce enough food.The lack of a major impact of the Green Revolution in thisregion is one key reason for this difference

income-gener-The Green Revolution is one of the major ments of the past 30 years During this period, the number

accomplish-of rural poor decreased by half, the proportion accomplish-of ished people in the world dropped from 30% to 18%, and thereal prices of main cereal crops decreased by 76% It wasinitiated by a small group of determined scientists and poli-cymakers who identified a need for high-yielding varieties ofrice and wheat Then enabling government policies, fertilizersand irrigation, better marketing, infrastructure, nationalresearch institutions, strong agricultural universities, the

malnour-Table 1.1 Basic Hunger Statistics in Developing Regions of the World

Region

Per Capita Food Production Index 1999/1961

Caloric Intake 1999 cal/person/day

Undernourished 1999

Source: Food and Agriculture Organization 2003 FAOSTAT: FAO Statistical

Data-base Available at: http://apps.fao.org/

Reducing Hunger in Tropical Africa while Coping with Climate Change 5

international agricultural research system, and other sary factors were put in place However, the contribution ofimproved varieties to crop yield increases has been 70% to90% in Asia, Latin America, and the Middle East, but only28% in Africa (Evenson and Gollin, 2003)

neces-A major biophysical reason and a major economic reasonhelp explain this discrepancy The major biophysical reason

is that unlike other developing regions, soil nutrient depletion

is extreme in Africa Therefore, the key need is not to improvevarieties, but rather to replenish soil fertility at the lowestpossible cost (Sanchez, 2002) Closely related to improvingsoil fertility is the need to improve small-scale water man-agement, provide small-scale rain-fed farms with critical life-saving irrigation, and grow high-value crops Soil fertility goeshand in hand with water in many regions Even with excellentgenetic improvements, crops cannot grow well without suffi-cient nitrogen, phosphorus, or water These are biologicalimperatives that transcend socioeconomic and political ones.The major economic constraint is poor rural infrastructure inAfrica Road density for rural dwellers in Africa is only one-sixth the average of Asia (Paarlberg, 2002) Hence, access tomarkets is difficult; fertilizer prices are two to six times higher

at the farm gate in Africa than they are in the rest of theworld; health, education, and sanitation are often appalling;access to information is poor; and prices drop precipitouslywhen crop surpluses occur

Research scientists have also learned that communityparticipation in research and development can work A newparadigm, based on natural resource management, hasemerged It addresses soil and water issues as well as pestmanagement constraints in ways that minimize tradeoffswith environmental services (Izac and Sanchez, 2001) Fur-thermore, an enormous biotechnology potential exists toaddress these issues through crop genetic improvement(Wambugu, 1999) We know more about the crucial need forfunctional markets for the poor, farm diversification, tradeimbalances, environmental services, and a reawakening of theimportance of agriculture as the engine of economic growth

It is very positive to see agricultural scientists interacting

6 Sanchez

with counterparts who focus on environmental, nomic policy, health, education, gender, water and sanitation,energy, and other development sectors

macroeco-1.1 REDUCING HUNGER IN AFRICA

The time is right to drastically increase the productivity ofAfrican agriculture and to improve human nutrition, with anew and highly focused action plan, called the Doubly GreenRevolution in Africa “Doubly green” means increasing pro-ductivity in environmentally sustainable ways (Conway,1997) In response to a request from the UN Secretary Gen-eral in February 2003, the U.N Millennium Project’s TaskForce on Hunger is developing a plan to attain the MillenniumDevelopment Goal of cutting hunger in half by 2015 (Millen-nium Project, 2005) The emerging plan is based on (1) movingfrom political commitments to concrete actions, (2) policyreforms that give high priority to investments in agriculture,nutrition, rural infrastructure, marketing, and rural women,and (3) three key interventions at the community level Thelatter interventions include (a) improving agricultural pro-ductivity on smallholder farms through investments in soilfertility restoration and small-scale water management; (b)making markets work for the rural poor through storagefacilities, feeder roads, market information systems, and otherinterventions; and (c) providing school lunches with locallyproduced food in order to increase school attendance, espe-cially by girls, to enable learning, improve nutrition, andincrease local demand for food production

These three synergistic community-based actions andoverarching policy reforms can break the log jam of inaction

in the short term, and open the way for other necessaryactions to take place if there is political commitment How-ever, the specter of climate change will make this task evenmore daunting The remainder of this paper addresses someadditional priority interventions that will facilitate copingwith climate change in Africa as well as in other tropicalregions

Reducing Hunger in Tropical Africa while Coping with Climate Change 7

1.2 COPING WITH CLIMATE CHANGE

The Third Assessment Report of the Intergovernmental Panel

on Climate Change (IPCC) stated for the first time that entific evidence of human-induced global warming is unequiv-ocal, and that the latest predictions are much worse thanprevious estimates (Houghton et al., 2001) The last 100 yearshave been the warmest on record Furthermore, warmingduring the last 50 years has a clear human signature Globaltemperatures will increase by 1.4°C to 5.8°C by 2100; sealevels are rising and are expected to increase by 14 to 88 cm

sci-by 2100, flooding low-lying areas and displacing hundreds ofmillions people Rainfall patterns are changing, El Niñoevents are increasing in frequency and intensity, Arctic ice isthinning, and tropical mountain glaciers are retreating.The consequences of these changes are also dire accord-ing to this report Agricultural productivity in Africa andLatin America could decrease by as much as 30% during thiscentury Severe droughts will occur in Southern Africa andSoutheast Asia Wetter climates and more floods are predictedfor parts of East Africa and Latin America And more smokeand haze problems are predicted for Southeast Asia and Cen-tral America Higher worldwide food prices are likely to result,negatively affecting the urban poor

Major changes are also predicted in critical ecosystems,particularly coral reefs and tropical forests The geographicspread of malaria and increased crop pest and disease pres-sure in wetter climates are also predicted The IPCC reportedglobal economic losses of around $40 billion due to existingglobal warming in 1999, of which 25% occurred in the tropics(Houghton et al., 2001) The capacity of people to adapt tothese global changes is correlated with poverty level Coun-tries with the least diversified agriculture, forestry, and fish-eries will suffer the most Africa is considered to be the regionmost vulnerable to global warming (Houghton et al., 2001)

A major discrepancy exists between developed and developingcountries in terms of human-induced global warming and who

emissions are due to fossil fuel burning, mainly from the

8 Sanchez

North, while the remaining 25% is due to changes in tropicalland use, especially deforestation in the South While contrib-uting the least to global warming, the tropical countries willsuffer the most from it

The following section includes a discussion of some keyresearch issues identified by the Consultative Group on Inter-national Agricultural Research (CGIAR) Inter-Center Work-ing Group on Climate Change (2001) The tropics will face aspecial challenge in coping with climate change Issues dis-cussed are arranged in terms of impact, adaptation, and mit-igation of climate change

Research about the projected impacts of climate change vides a predictive understanding of the processes involvedand their consequences Many models used to predict impacts

pro-of climate change are based on obsolete primary tropical datasets These data often keep being recycled in climate changestudies, creating self-evident truths by continued quoting.Some studies acknowledge that such data sets are admittedlyinadequate, but researchers continue to use them becausethey are unable to find better ones Many models also expressresults in spatial scales that are of little use to nationalscientists and decision makers The following three examplesillustrate how some of these limitations can be overcome

1.3 ESTIMATING BIOMASS OF YOUNG

TROPICAL VEGETATION

Allometric equations for estimating tropical forest biomass(Brown et al., 1989) were developed for mature forests by theIPCC The equations provide the basis for estimating theimpact of tropical deforestation on the global carbon cycle.But such equations significantly underestimate biomass car-bon in young tree vegetation that occupies about 72% of theoriginal tropical forest area New allometric equations devel-oped by Ketterings et al (2001) for young secondary forestsand fallows in Indonesia result in biomass estimates that only

Reducing Hunger in Tropical Africa while Coping with Climate Change 9

approximate those obtained using the equation by Brown et

al (1989) The use of these equations plus new hard data havechanged the image of Indonesia, which has to be regarded anet carbon sink instead of a net carbon source (Van Noordwijk

et al., 1995)

1.4 HOW TO MEASURE SOIL CARBON

The IPCC special report titled Land Use, Land Use Change

and Forestry (Watson et al., 2000) notes that the inability to

accurately measure changes in soil carbon at low cost is amajor impediment for carbon sequestration projects It isequally applicable to projects related to the Clean Develop-ment Mechanism (CDM) in Article 12 of the Kyoto Protocol.Soil carbon has enormous spatial variability and accuratemeasurement requires the collection of multiple soil samples

at different times, as well as laboratory analyses to obtainestimate of changes in soil carbon Based on extensive sam-pling in Africa, Shepherd and Walsh (2002) have developed apromising approach that estimates several soil propertiessimultaneously using diffuse reflectance spectroscopy in rapidnondestructive ways The measurement of soil carbon, as well

as other soil properties, can be predicted using soil reflectancespectra with accuracy similar to that of duplicate laboratorydeterminations

Because this spectral technique allows large numbers ofsamples to be quickly analyzed, it can be used to thoroughlycharacterize the soil and its spatial variability within a CDMproject The problem of large spatial variability in soil carbondeterminations is addressed by making many measurements,each of which only takes nanoseconds By returning to thesame site at a later date, it is possible to quantify the amounts

of soil carbon sequestered or released consistent with CDMverification requirements This technique can use spectralbands from satellite imagery, thus permitting remote sensinganalysis (Shepherd and Walsh, 2002)

the maize caloric deficit in Southern Africa caused by bothclimate change and population growth The subnational level

of resolution, as well as the easily interpretable nature of suchmaps, makes this alternative more useful to policymakersthan country-level resolution, single-factor assessments

1.6 ADAPTING TO THERMAL DAMAGE

The mean maximum temperature for much of the tropics

Report indicates that temperatures are going to increasethroughout the tropics, regardless of changed rainfallregimes J Sheehy of the International Rice Research Insti-tute (2003) has observed that the fertility of rice flowers falls

perature due to global climate change is potentially damaging

temperature Similar trends have been found in wheat, maize,beans, soybeans, and peanuts

Figure 1.1 shows an example of this approach It predicts

tem-Reducing Hunger in Tropical Africa while Coping with Climate Change 11

Figure 1.1 Maize calorie deficit (kcal/person/day) in SouthernAfrica caused by climate change and human population growth in

2050 (From Jones and Thornton, 2001)

Figure 1.2 Relationship between grain sterility and maximum

in the atmosphere (From J Sheehy, personal communication, 2003)

750-1000 500-750 250-500

< 250

No change Mozambique

12 Sanchez

Large increases in the sterility of cereal and legume cropsare related to temperature increases They represent analarming food security issue, which increases challenges thatthe world faces to feed itself in the coming decades The extent

of this threat to root and tuber crops, pasture, and tree species

in unknown If the rates of rice yield decline due to thermalstress are broadly validated, and assuming that temperature

2% to12% by the year 2020, and by 7% to 29% by the year

2050 The IPCC Third Assessment Report does not considerthermal damage to grain crops in its predictions, but accord-ing to J Jones (2003) some models are now incorporatingthermal damage into their predictions

A full assessment of this threat needs to be done Geneticmanipulation offers several approaches, including breedingfor resistance to higher temperatures during flowering time;shifting the time of day at which crops flower to avoid thehottest hours; and gene transfers from crops that toleratehigher temperatures, such as sorghum and millet, to rice andmaize It is also possible to manipulate the microclimate Anexample is the marked reduction in air temperature when

sorghum and millet are grown under Faidherbia albida trees

in the Sahel (Vandenbeldt, 1992)

1.7 MITIGATION

Since most carbon is emitted through fossil fuel combustion,mitigating global warming will logically depend on what hap-pens in the Northern Hemisphere One key exception is theimportant role of carbon sequestration in the tropics

1.7.1 High Carbon Sequestration Potential of

Tropical Agroecosystems

A recent IPCC study on land use, land-use change, and estry (Watson et al., 2000) documented the large potential fortropical agroecosystems to sequester carbon The tropics havetwo major advantages over the temperate regions Trees grow

for-Reducing Hunger in Tropical Africa while Coping with Climate Change 13

faster under high year-round temperatures and high solarradiation In addition, many tropical soils are depleted ofcarbon because of unsustainable land use practices Table 1.2illustrates the potential for carbon sequestration in thetropics

Land use intensification practices usually start from ahigh carbon stock base, resulting in annual sequestration

Table 1.2 Carbon Sequestration Rates and Annual Potential of Agricultural Practices by 2010

Practice

Carbon Sequestration Rate (tons C/ha/year)

Annual Potential

by 2010 (million tons C/year) Land Use Intensification (Global)

Croplands (reduced tillage,

rotations, cover crops,

fertilization, and irrigation)

Forest lands (forest regeneration,

better species, silviculture)

Grasslands (better herds, woody

plants, and fire management)

Lowland rice production 0.10 <1

Land Use Change (Tropics)

Agroforestry (conversion from

unproductive croplands and

grasslands at humid tropical

forest margins, and by

replenishing soil fertility in

subhumid tropical Africa)

Improved pastures in subhumid

tropical South America

(conversion from native

pasture to deep-rooted

improved grasses and legumes)

2.8 without a legume, 7.0 with a legume

14 Sanchez

rates of tenths of a metric ton per hectare, in both tropicaland temperate regions Because of the large areas, the totalcarbon sequestration potential by 2010 ranges from 50 to 168

Mt (million metric tons) per year, except for paddy rice duction because of methane emissions associated with it Transforming unproductive tropical croplands or grass-lands into highly productive agroforestry and improved pas-ture systems results in annual carbon sequestration rates of

pro-a higher order of mpro-agnitude Trees pro-are periodicpro-ally hpro-arvested

in agroforestry systems Thus, these calculations refer to averaged carbon, which takes into account carbon removalsassociated with harvesting (Palm et al., 1999) The highsequestration rates in these land-use change categories aredue to a drastic increase in biomass production Either orig-inally fallow lands have lost much of their system carbon stock

time-in the agroforestry systems (Sanchez and Jama, 2002) or anew sink of carbon has been developed in the subsoil (Fisher

et al., 1994) Given the large areas to which these conditionsapply, the overall potential for additional carbon sequestra-tion is huge Conversion to tropical agroforestry has the poten-tial to soak up 390 Mt of carbon per year, equal to about one-fifth of annual carbon emissions of the United States from allsources

The importance of avoiding further deforestation is carbon is enormous, and avoidance of such emissions by pre-venting deforestation will play a major role in the globalcarbon cycle

evi-The magnitude of carbon sequestration in developingcountries through systems described in Table 1.2 depends to

a major extent on rainfall regimes The carbon sequestrationpotential per hectare of such systems is lowest in the semiaridtropics and highest in the humid tropics, with the subhumidtropics in between (Schroeder, 1994) Hotspots could be iden-tified at a similar scale of resolution as the well-establishedbiodiversity hotspots However, there are tradeoffs betweencarbon sequestration per hectare, and the number of hectaresthat can be put into such systems The carbon sequestrationpotential in the Sahel is in the range of 0.25 to 0.05 tons of

Reducing Hunger in Tropical Africa while Coping with Climate Change 15

carbon per hectare per year (Sloger, 2003), or one-tenth ofwhat land use change with legume-based pastures or agro-forestry can yield in the subhumid and humid tropics How-ever, there are large areas of degraded lands in the dry areasstretching from Morocco to Mongolia for which land usechange could make a major difference, even if the sequestra-tion rates are low on a per hectare basis

Farming Communities

Most carbon offset projects involve a large carbon emitter in

process excludes many farmers from the process Given the

in substantial carbon reductions in the atmosphere, sinceprimary forests are mature, and most of the carbon seques-tered by photosynthesis in them is lost by respiration Tosequester large quantities of carbon, one must work withyoung secondary forests or agroforests

Poor farmers in the tropics could benefit financially bysequestering carbon It is a product they provide to the globalcommunity when using the other practices described in Table1.2 This idea was proposed by the CGIAR Inter-Center Work-ing Group on Climate Change at a meeting of the subsidiarybodies of the UN Framework Convention on Climate Change

received by developing country representatives and donoragencies It represents a potential integrated approach to foodsecurity/poverty alleviation issues because it would alsoinvolve carbon sequestration as a “no-regrets” option.Research needs to be done to determine how the sequesteredcarbon can be accounted for in a heterogeneous landscapethat includes hundreds of small farms, and about how benefitscould accrue to farmers Payments for sequestering carbon

ment to protect a large area of primary forest from

tation, thereby avoiding the emission of more carbon This

an industrialized nation contracting with a tropical

www.iisd.ca/cli-mate/sb13/side/enbots11mon.htm) The idea was well

per-by linking it to carbon sequestration payments, thus helping

to mitigate climate change as well

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Brown, S., A.J.R Gillespie, and A.E Lugo 1989 Biomass estimationmethods for tropical forests with applications to forest inventory

data For Sci., 35:881–902.

Conway, G 1997 The Doubly Green Revolution: Food for All in the

21st Century Penguin Books, London.

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Dixon, J., A Gulliver, and D Gibbon 2001 Farming Systems and

Poverty Improving Farmers’ Livelihoods in a Changing World.

Food and Agriculture Organization, Rome

Evenson, R.E and D Gollin 2003 The Green Revolution at the End

of the Twentieth Century CAB International, Wallingford,

Food and Agriculture Organization 2002–2003 FAOSTAT: FAO

Houghton, J.T., Y Ding, D.J Griggs, et al., Eds 2001 Climate

Change 2001: The Scientific Basis Cambridge University Press,

London; New York

Inter-Center Working Group on Climate Change 2001 Beating theHeat: Climate Change and Rural Prosperity Report to Consul-tative Group on International Agricultural Research Mid-TermMeeting, Durban, South Africa World Agroforestry Centre,Nairobi, Kenya

Izac, A.-M.N and Sanchez, P.A 2001 Towards a natural resourcemanagement paradigm for international agriculture: the exam-

ple of agroforestry research Agric Syst., 69:5–25.

Jones, J Distinguished professor, Agricultural and Biological neering Department, University of Florida Personal communi-cation, 2003

Engi-Jones, P.G and P.K Thornton 2001 Spatial modelling of risk innatural resource management: applying plot-level, plant-

growth modelling to regional analysis Conserv Ecol 5(2), 27.

Ketterings, Q.M., R Coe, M van Noordwijk, Y Ambagau, and C.A.Palm 2001 Reducing uncertainty in the use of allometric bio-mass equations for predicting aboveground tree biomass in

mixed secondary forests For Ecol Manage., 146:201–211.

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