Climate change impacts cocoa farming Solomons WEB · 2018-04-06 · Climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands 5 Process overview This

A preliminary case study assessment of climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands

A preliminary case study assessment of climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands

b Climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands

© Solomon Islands Meteorological Service (SIMS), Secretariat of the Pacific Regional Environment Programme (SPREP) and Commonwealth Scientific and Industrial Research Organisation (CSIRO) 2018

This publication should be cited as:

SIMS, SPREP and CSIRO (2018). A preliminary case study assessment of climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands. CSIRO, Melbourne, Australia.

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The results and analyses contained in this publication are based on a number of technical, circumstantial or otherwise specified assumptions and parameters. To the extent permitted by law, CSIRO excludes all liability to any party for expenses, losses, damages and costs arising directly or indirectly from using this publication.

Climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands 1

Growing cocoa is a valuable industry for smallholder farmers in the Guadalcanal Plain, Solomon Islands, and more generally provides a significant national social and economic benefit. The climate of Guadalcanal Plain is currently suitable for growing cocoa, although there are various climate impacts on the industry, including:

• Periodicfloodingthatdamagesfarms(e.g.floodin2013)

• Tropicalcyclones,notingthatthemainimpactistheflooding(soisconnectedtothefirstrisk)whilewindspeedhaslittlenegativeimpact

• Heavyrainfallthatdamagesflowersandsubsequentlevelsoffruitingonthetrees,andalsocausesdamaging(‘blackpod’)fungaldiseaseoutbreaks–annualrainfallandassociatedhumidityisoftenhighenoughforthefungaloutbreakstobesevere,andheavyrainfallandhumiditypromotesthespreadoffungusbetweencocoapods.

Theseriskshavethepotentialtobecomeworseinthefutureunderachangingclimate,andothernewclimate-relatedrisksmayalsoarise.

A preliminary assessment of climatechangeprojectionsfortheGuadalcanalPlainfound:• AverageannualdailymaximumtemperaturesintheGuadalcanalPlaincouldbeabovethe30–32°C thresholdforgrowingcocoabyabout2050,possiblysoonerunderaworst-casescenario.Beyond2050andoutto2090thereisastrongeffectofemissionsscenarios–underalowemissionsscenariothereissomeriskofbecomingtoowarm,butunderahighscenariothereisaveryhighriskofbecomingtoowarm.

• Averageannualrainfallprojectionsareuncertain:climatechangemaylead to an increase in rainfall but theremayalsobelittlechange.ThismeansaccordingtosomeprojectionsthatpartsofGuadalcanalmaybecomelesssuitablebybeingtoowetunderahighemissionsscenariobytheendofthecentury,butaccordingtootherprojectionstheymaynot.ThemostvalidmodelprojectionsforGuadalcanalPlainrequiresfurtherevaluation.

• Theconditionsforseverefungaldiseaseareveryunlikelytogoaway–suitablyhighannualrainfallyearsandextreme(heavy)rainfalleventsthatspreadthesporesarelikelytocontinuethroughthecentury,andcouldwellbecomemoresevereundertheworst-case emissions scenario.

• Theincidenceoflocalisedfloodingmayincreaseinaverageintensityand/orfrequencyoverthelongerterm,butwithhighyear-to-yearanddecade-to-decadevariability.

Otherclimatechangesmayoccur,includingchangestohumidityandsolarradiation.Also,theremaybeclimateimpactsonnotonlythegrowingconditionsbutalsothesupplychainandtherelativeadvantageoftheSolomonIslandscomparedtoothercountries(notingthatcocoaisaviableand,inmanycases,expandingindustrysectorinmanycountriesaroundtheworldsubjecttovariousambientclimateconditions,bothcurrentandfuture).

Thecombinationofalltheserisksislikelytocausesomeongoing,andinsomecasesincreasing,challengestotheindustryintheperiodbeyond2030,andespeciallyafter2050ifwecontinuetofollowahighemissionsscenario.Thesechallengeswillneedtobemanagedthroughvariousfarmand industry-scale climate adaptation andassociatedriskmitigationmeasures in order to build resilience andsustainabilityforsmallholdercocoafarmersintheGuadalcanalPlain.

Thereareseveralwaysinwhichtheindustry can become more resilient tochallengessuchasclimaterisk,includingintroductionofnewfarmmanagementandassociatedcultivationandharvestpractices,farminginnewareas,changingtheplantingmaterialandstocktomoretolerantvarieties,anddiversifyingthefarmingsystemtoincorporateotherproducts.Furtheranalysis of adaptation options can be found in Vulnerability of Pacific Island agriculture and forestry to climate change(Tayloretal.2016).

Assessment summary

2 Climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands

1 Contributions from John Konam, pers. comm.2 Science-Based Climate Information Services in the Pacific: Communicating New Findings,

Supporting Application and Developing In-Country Capacity, CSIRO 2017

Socioeconomic contextCocoahasbeengrowninGuadalcanalsincethelate1950sandhasgonethroughseveralperiodsofdevelopmentandexpansion.

Today,thecocoaindustryintheSolomonIslandsisentirelysmallholderbased.Itisestimatedthatmorethan20%ofthepopulationgrowscocoa.Intermsofgeographicalcoverage,estimatedat10,000–15,000ha,itisthesecondmostimportantcashcropaftercopra.CocoaisgrowninallprovincesexceptRennell/Bellona.HighestproductionisinGuadalcanal,followedbyMalaitaandthenMakira.Cocoaisthethirdmostimportantexportcommodity(behindloggingandfishing)andwastheleastaffectedbythesocialunrestinSolomonIslandsbetween1999and2003.

TheSolomonIslandscocoaindustryisrobustbecause:• Cocoaisafamily-friendlycropmostlygrownbysmallholderswithlowoverheadcostsaspartofamixedcroppingsystem.

• Therearereasonableeconomicreturnstosmallholderfarmlabourcosts,evenwhenmarketpricesarerelativelylow.

• Thereisacompetitivedomesticmarketingsystemtogetherwithstrongexportmarketdemand.

• Increasesintransportationandotheroperatingcostscanbeabsorbedbysmallholderfarmersduetoitsrelativelyhigherunitmarketvalue.

CocoahasbeenidentifiedbytheSolomonIslandsMinistryofAgricultureandLivestock(MAL)asaproductwithpotentialforeconomicdevelopmentforsmallholderfarmers.Inrelationtopotentialimpactsfromclimatechange,theMALandfarmershaveexpressedsignificantinterestinimprovingtheirunderstandingofthefutureclimatein

theirregionalongwiththeimpactsthismayhaveontheircrops,productsandlifestyles.ThereislimitedinformationcurrentlyavailablespecificallyfortheimpactsofthechangingclimateoncocoafarmingintheSolomonIslands.

Cocoa production and current climate vulnerabilityClimatefactorsaffectingthegrowthofcocoainclude:• Rainfall:totalannualrainfall,rainfalldistribution,theintensityofrainfallevents(particularlyonflowering)andtherelativedrynessanddurationofthedryseasonareimportantascocoaisverysensitivetowaterstress(bothtoomuchandtoolittle).

• Humidity:highrelativehumidity(>70%)isconducivetoproliferationofblackpod(Phytophthora palmivora)fungaldisease.

•Winds:regularstrongwindsare unsuitable for cocoa.

• Solarradiation(sunlight):cocoaneedsaround75%sunlightasexposuretostrongsunlightwillreducetreecarbondioxideassimilation.

• Temperature:cocoagrowthandfloweringisdirectlyrelatedtoairtemperature,withthebestrangeforcultivation25–30°C.

BlackpodisaseriousplantpathogeninGuadalcanalthatspreadsthroughrainsplashandhumidconditions,aswellasviainsectvectors.

ThemajorcroppingseasonisApriltoJuly(withflowerandfruitsetinOctobertoDecemberofthepreviousyear).ThereisalsoaminorharvestfromOctobertoDecember(withflowerandfruitsetaroundApriltoDecember).Extremeraineventscandamageflowersandsubsequentfruitset, and adequate dry seasons (for solardrying)areneededtoprocesstheharvestedcocoaforqualitybeans.

About this case studyAspartofanAustralianGovernmentfundedproject2designedtofacilitateoutreachofexistingPacificclimatechangesciencedataandinformationtosectoralpolicymakers,theSolomonIslandsMeteorologicalServiceusedtheirexpertise,alongwiththesupportoftheAustralianCommonwealthScientificandIndustrialResearchOrganisation(CSIRO)andtheSecretariatofthePacificRegionalEnvironmentProgramme(SPREP)toworkwiththeMALandcocoafarmerstoundertakeapreliminaryclimatevulnerabilityandriskassessmentoncocoafarmingintheGuadalcanalPlain.Theassessmentincludedbothback-officecollationandanalysisofdataandinformationaswellasasubsequentstakeholderworkshopinHoniaraduringAugust2017.

Theassessmenthasthreegoals:1.Awarenessraising–theresultscan

be used to start discussions and raise awarenessofthepotentialclimatechangeimpactsoncocoafarmingforstakeholdersintheSolomonIslands.

2.Climatechangeimpacts–providedecisionmakerswithapreliminaryillustrationofthepotentialimpactofclimatechangeonthegrowingconditions of cocoa; to be used as input to a more detailed climatechangeriskassessment,adaptationplanningandassociated analysis of adaptation optionsandactionplanning.

3.Motivatingmitigation–illustratetheeffectofemissionsscenarios,todemonstratetothegovernmentthebenefitofemissionsreductionsforpurposesofinforminginternational(UNFCCC)negotiations.

Background1


Searchesoftheliteratureandengagementswithkeystakeholdersidentifiedfourkeyclimaticfactorsrelevanttococoafarming:A. Temperatureenvelope

forgrowingcocoaB. Averageannualrainfalland

dry season rainfallC. FungaldiseasePhytophthora

palmivora(relatedtohighrainfall)D. Extremerainfallevents,

floodinganddryspells

Thiscasestudyexaminedthesefactorswithregardtopotentialclimatechangeimpactsandthefutureofthecocoa industry in Solomon Islands. Whilethesefactorsshowsomeofthepotentiallymostimportantdirectimpactsfromachangingclimate(andthereforedemonstratethevalueandprinciplesofundertakingaclimateriskanalysis),therearemanyotherclimate and non-climate related issues thatneedtobeassessedbeforetheoverallclimatechangeriskcanbeunderstood.Theseinclude:

• solarradiationandhumidity• cocoaborerandother

pests and diseases• farmmanagementpracticesandthecocoasupplychain(processing,storage,transport,etc.)

• therelativeadvantageordisadvantageoftheSolomonIslands cocoa industry compared toproductioninotherdevelopingcountries(PapuaNewGuinea,Ghana,IvoryCoastandothers)

• arangeofotherrelevantsocio-economicfactorsimpactingonthepractices,lifestylesandwellbeingofsmallholdercocoafarmersintheGuadalcanalPlain.Figure 1. Map of the Solomon Islands, Guadalcanal Island and the Guadalcanal

Plain on the north side of Guadalcanal. The Bethsaida cocoa farm (circled) was visited during the assessment. (Map from Raymond Vava, MAL)

Solomon Islands Guadalcanal Island

Guadalcanal Plain



ProcessoverviewThispreliminary(alsoreferredtoas‘rapid’)assessmentwascarriedoutaspartoftheAugust2017workshopinHoniarausingdraftguidelinesdesignedtoassistsectoralstakeholdersinthePacificdevelopandapplyclimatechangedataandinformationforriskassessments.Theeight-stepprocessisbrieflysummarisedbelow.Detailedinformationisavailableintheguidelinedocument3,whichisavailableatwww.pacificclimatechangescience.org.TheworkshopalsoservedthepurposeoftriallinganddemonstratingtheuseofthenewguidelinesforothersectorsinSolomonIslandsaswellasforotherPacificIslandCountries.

1. Identify stakeholders and plan engagement

2. Determine climate change information needs

STAKEHOLDER ENGAGEMENT







3. Find existing climate change information

4. Collect observed climate data

5. Collect and evaluate climate model data

6. Construct climate change projections

7. Assess climate change risk

8. Communicate climate change information

Identifyingandengagingstakeholdersiscriticaltothesuccessofanyriskassessment.Theimplementationofthestakeholderengagementplanisanimportantaspectofeachofthesubsequentstepsinthisprocess.

Itisimportanttobeclearaboutthepurposeoftheactivity,aswellasidentifyingimportantclimatechangesystemsandthresholds,variablesandrelevanttimeframesandsteps.

Existingclimatechangeknowledgeisusedtoprovidecontextfornewanalyses(gotostep4),toundertakeriskassessments(gotostep7)andtoformthebasisofcommunicationproducts(gotostep8).

Observedclimatedataputsclimateprojections(developedinstep6)intothecontextofwhattheclimatehasbeenlikeinthepastandislikenow.

Climatemodeloutputsareusedtogenerateclimatechangeprojections,butwithmanymodeloutputsanddatasetsavailable,itisimportanttoselectthemostappropriatefortheassessmentbeingundertaken.

Application-readydatafromclimatechangeprojectionsareconstructedbyapplyingclimatemodelprojectionstoobserveddata,eitheraschangesinaverageclimateorasnumberofdaysoverorunderathreshold.Projectionsandassociatedapplication-readydatacanbeusedinariskassessment(gotostep7)orforcommunicationpurposes(gotostep8).

Thereareanumberofapproachestoundertakingaclimatechangeriskassessment,butallinvolveidentifying,analysingandevaluatingtherisk.

Effectivecommunicationofclimatechangeinformationrequiresanunderstandingoftheobjective(s)oftheriskassessmentandthetargetaudiences,sotheinformationisconveyedinawaythatisusefulandrelevant(andsomorelikelytoberememberedandactedon).

3 Developing climate change information for the Pacific: guidance material to raise awareness and facilitate sectoral decision-making using science-based climate change information and services (CSIRO and SPREP, 2017)

http://www.pacificclimatechangescience.org


4 See: http://www.pacificclimatechangescience.org/

STEP 1 Identify stakeholders and plan engagementTheprojectteamengagedwitharangeofstakeholdersandexpertsateachstepoftheassessmentprocess.Engagementactivitiesincluded:• AstakeholderworkshopinHoniara(August2017)

• Afieldvisittoaworkingcocoafarmandinterviewswithgrowers(August2017)

• EmailcontactswithresearchersandcocoafarmingstakeholdersinSolomonIslands(January–August2017).

Thekeystakeholdersforthiscasestudyincluded:• theSolomonIslandsMinistryofAgricultureandLands,includingpolicymakersandextensionexperts

• Solomon Islands MeteorologicalService

• CocoafarmersintheGuadalcanal Plain

• SecretariatofthePacificRegionalEnvironmentProgramme

• CSIROClimateScienceCentre.

Thisengagementwasessentialinassessingandidentifyingwhichclimatevariablesaremoreimportantforcocoafarmingthanothers,andleddirectlytosomechangesinidentificationandinterpretationoftherelevantresearchdataandinformationtoinformtheassessment,including:• Theimpactoffloods–theassessmentinitiallydidn’tlookatfloods,buttheimportanceofthisimpactbecameclearfrominterviewingcocoafarmersabouttheirexperienceandobservationsonclimateandweatherinthepast.

• Fungaldiseaseconditions–theassessmentdeterminedthatnotonlydoeshighannualrainfallcreatetheconditionsforfungaldiseasetogrow,butheavyrainfallonthecocoapodsincreasesthespreadoffungaldisease.

• Flowering–itwasmentionedbycocoafarmersduringthefieldvisitthatheavy(extreme)rainfalleventsoftendestroythefloweringbudsresultinginlowercocoafruityield.

Otherimportantconsiderationsthatwereidentifiedthroughstakeholderengagementwere:• Thelistofpotentialadaptationsincludingpracticaloff-farm/supply-chainoptionssuchasthefarmerbenefitsfromhavingawarehouseawayfromthefarmtosafeguardharvestedcropsduringfloods.

• Ensuringtheusefulnessofthefinalriskassessmentoutputsatnationallevel–itwasidentifiedthattheprimarytargetgroupisMALdecisionmakersforplanningpurposes,whothenhavetheresponsibilityforusingtheinformationtoraiseawarenesswithcocoagrowers.Hence,twodifferentreportswereneededtobeprepared to disseminate information fromtheassessmenttothefullrangeof‘next’and‘end’users.

• Theneedtodevelopcapacityforsectoraldecisionmakersandfor farmers at a local community scaleonclimatechange,extremesandvariability,andhowtouseclimatechangeknowledgeasadecision-makingtool.

• A detailed assessment is ultimatelyrequiredtoachieveamorecomprehensiveclimateadaptationresponse,butthisrapidassessmentapproachisappropriateastheentrypoint.

STEP 2 Determine climate change information needs – the research questionsAspreviouslynoted,searchesoftheliteratureandengagementswithkeystakeholdersidentifiedfourkeyfactorsrelevanttococoafarmingandclimate:A. Optimaltemperatureenvelope

forgrowingcocoaB. Averageannualrainfalland

dry season rainfallC. FungaldiseasePhytophthora

palmivora(relatedtohighrainfall)D. Extremerainfallevents,

floodinganddryspells

Tostudythesefourfactors,weneedtoshowthe‘envelope’oftheaverageclimateconditionsforgrowingcocoaontheGuadalcanalPlain,andhowitcouldchangeinthefuture.Wealsowantsomegeneralinformationaboutprojectedchangestoheavyrainfallandfloods.

Forourfouranalysisareas,theresearchquestionsare:• Howwillthetemperatureconditionsforgrowingcocoabeaffectedunderfutureclimatechangescenarios,andcould parts of Guadalcanal become toowarmforgrowingcocoa?

• Underfutureclimatechange,couldtheaverageannualrainfallbecometoowet,orcouldtherebetoomanydrymonthsforgrowingcocoainGuadalcanal?

• Underfutureclimatechange,couldthefungaldiseasebecomeagreaterorlesserthreatforgrowingcocoainGuadalcanalthanitiscurrently?

• Couldextremerainfalleventsand/orfloodingfromtropicalcyclonesorothersourcesbecomemorefrequentormoreintenseonaverage?

http://www.pacificclimatechangescience.org/


STEP 3 Find climate change informationAliteratureandinternetsearchrevealsthatthereissomeusefulgeneralinformationaboutcocoafarmingintheSolomonIslands,includingachapterintherecentlypublishedbookbytheSecretariatofthePacificCommunity(SPC)onclimatechangeandagriculture(McGregoretal.2016).AdetailedanalysisoftheclimateenvelopeforcocoainAfricahasbeendonepreviously(e.g.Läderachetal.2013).However,therearenodetailedpreviousstudiesoftheoptimaltemperatureenvelopeforcocoagrowingspecificallyforGuadalcanal;soweneedtodonewanalysis.Thetemperatureandrainfallthresholdsoftheclimateenvelopeforcocoagrowingingeneralarefairlywellknown.AccordingtoMcGregoretal.(2016)therelevantclimateconditionsare:• Annualaveragedailymaximumtemperature(Tmax)upto30–32°C

• Annualaveragedailyminimumtemperature(Tmin)upto18–21°C

• Annualaveragerainfallof 1250–3000mm(1500–2000mm isoptimum)

• Nomorethanthreemonthsofrainfalloflessthan100mm/monthperyear

• Fungaldiseaseismostseverewhenannualrainfallisabove2500mm.

Tofullyassesstheriskwithfloodingwecan’tjustusetheaverageclimate,ratherweneeddetaileddailyrainfalldatasetsandhydrodynamicandgeomorphologicalinformationaboutlocalisedfloods(e.g.theshapeofcatchmentsandfloodplains,drainagecapacityandratesofrun-off,etc.).Asthiscasestudyis based on a rapid assessment ofchangeinfloodriskweareonlyusingexistingandavailabledataandinformation,withnonewanalysis.

Tothisend,previousworkfortheSolomonIslands(AustralianBureauofMeteorologyandCSIRO20144)hasfound:• Extremewetdaysareprojectedtoincrease,wherethe1-in-20-yeareventcouldbecomea1-in-9-yeareventundermoderateclimatechange(RCP2.6),ora1-in-4-yeareventunderaworst-caseemissionsscenario(RCP8.5)by2090

• Extremewetseasonsmayincrease(e.g.extremeswingsoftheElNiñoSouthernOscillation)

• Tropicalcyclonesvaryalotdecadetodecade,butoverthelong-termtheaveragenumberofcyclonesmaydecrease,butmoreoftheonesthatdooccurmightbeintense.

Alltheseresultssuggestthatfloodingwillcontinuetovaryalotyeartoyearanddecadetodecade,butovertimetheriskoffloodsandextremerainfalleventsislikelytoincreaseduringthiscentury,especiallyunderahighemissionsscenario.

STEP 4 Collect observed climate dataGrowingconditionsarehighlylocalised,sohigh-resolution‘surfaces’oftheaverageclimatethataccountforfactorssuchaselevation(highergroundiscoolerthansealevel)areneeded.Onlyrecentaverageconditionsareneededratherthantimeseriesorspecificinformationaboutextremeevents.High-resolutionclimatesurfacesforeachmonthareavailablefromWorldclim(Version2)atwww.worldclim.org.

Thesedataprovideclimateaveragesforthe1970–2000period.Thehigh-resolutionversionhas~1km2 resolution.Itusesweatherstationdata and satellite data as input and fillsthegapsbetweendatapointsbyusingstatisticaltechniques(thin-platesplinesandcovariatesusingelevation).Alltemperaturedatasetsrelyheavilyonhigh-qualityweatherstationswithgoodcoverage.TheSolomonIslandsisnotwellcoveredbystations,sotheaccuracyofthetemperaturedatawillnotbeashighasinsomeotherplaces.FormoreinformationseeFickandHijmans(2017).

DailymaximumtemperaturefortheSolomon Islands is currently under thelimitof32°C(Figure2).Averageannualrainfallisunderthe3000mmlimitexceptinthemountains,buttheaveragerainfallisabovethe2500mmlimitforfungaldiseaseinmanyplaces(Figure3).TheGuadalcanalregionhasbetweenzeroandfourmonthswithlessthan100mmofrainfall,onaverage(dryyearshavemoremonths,wetyearshavefewermonthsunderthethreshold).Inanaverageyear,theonlyareathathasfourormoremonthswithlessthan100mmisasmall area of coast near Honiara.

http://www.worldclim.org


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Suitability for cocoa, 1970–2000

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Figure 2. The average annual daily maximum temperature of Guadalcanal in 1970–2000 (left) (source: www.worldclim.org). The panel to the right shows the areas that are below the 32 °C limit (green means suitable).

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Figure 3. Average annual rainfall in Guadalcanal in 1970–2000 (left) (source: www.worldclim.org). The middle panel shows the area that is currently within the 1250–3000 mm growing limit (green) and the area that is too wet (red). The panel to the right shows the areas where the average annual rainfall is below (green) or above (red) the 2500 mm limit for severe fungal disease outbreaks.

http://www.worldclim.org


STEP 5 Collect and evaluate climate model dataFortheanalysisoftemperatureandrainfall‘changefactors’areneeded–theestimatedchangeintheclimatebetweenabaselineperiodandfutureperiods.Thesechangefactorsareneededforaverageannualdailymaximumtemperature,averageannualrainfallandforeachmonthtocalculatethenumberofmonthswith<100mm.Thesedataareneededforalltheemissionsscenarios(RCPs)toillustratetheriskunderalowemissionsscenariocomparedtohigheremissionsscenariostoshowthebenefitofmitigation.Guadalcanalisfairlysmall,soasinglechangefactorforthewholeislandisenough.Thereisnohigh-resolutiondownscalingavailabletouseforSolomonIslands,sothisassessmenthasjustusedtheavailablesetofCMIP5globalclimatemodelsasinput(AustralianBureauofMeteorologyandCSIRO2014).

Basedonthesedata,therangesofchangemeetalltheserequirements.DatafromAustralianBureauofMeteorologyandCSIRO(2014)useagroupofCMIP5globalclimatemodelsthathavebeenevaluatedanduseonlytheacceptablemodels–threeunsuitablemodelswererejected(Groseetal.2014).

DatafromAustralianBureauofMeteorologyandCSIRO(2014)presentsrangesofprojectedchangethatareplausible,andvaluesareavailableforalltheRCPsforvarioustimeperiods.TherangesofprojectedchangearenotedinFigures4and5.Thelowerlimits(cold)arenotaproblemintheSolomonIslandsandareveryunlikelytobeaprobleminfuture,sothefocusisontheupper(warm)limit.

STEP 6 Construct climate change projectionsFortheanalysisoffuturetemperatureand rainfall conditions in Solomon Islandswecanapplytheprojectedchangetotheobserveddatasetusingasimplescalingapproach–adjustingtheobservedclimatesurfaceupordownusingthechangefactorfromprojections.

Theabsolutechangeintemperatures(°C)isappliedusinganaddition:current + change = future

Theproportionalchangeinrainfall(%)isappliedusingamultiplication:current × %change = future

TwochangefactorsareappliedforeachtimeperiodandeachRCP:thelowerendoftheprojectedrange,andtheupperend.Forexample,iftheaveragedailymaximumtemperatureinaspatialgridcellis29.5°Candtherangeofprojectedchangeis1.5–2.8°C,thenthefuturevalueofthatcellis31–32.3°C.Followingthis,thevaluesthatareoverathresholdarefound.Thecelliscategorisedintooneofthreecategories:1.Therangeoffutureconditionsisbelowthethreshold.

2.Therangeoffuturetemperaturecrossesthethreshold(thehighvalueisover,thelowisunder).

3.Therangeoffuturetemperatureisallabovethethreshold.

Fortheexampleinthiscasestudy,thetemperaturerangeof31–32.3°Cforathresholdof32°Cwouldbeincategory2(thelowendoftherangeof31°Cisbelowthethresholdof32°C,andthehighendof32.3°Cisaboveit).Notethatthebaselinesareslightlydifferentbetweentheobservations

andtheprojections:1970–2000forWorldclimobservations,and1986–2005fortheAustralianBureauofMeteorologyandCSIRO(2014)projections.Theobserveddataortheprojectionscan’tbeadjustedsotheresultsareusedastheyareandthispointiscommunicatedintheresults.

STEP 7 Assess climate change riskA. TemperatureThedailyminimumtemperatureresultsaresimilartodailymaximumfortheSolomonIslands,sojustthedailymaximumsareshownhere.Thethresholdisfairlybroad(30–32°C)andsomeofthecurrentaveragesarequiteclosetothisthreshold,sotheexactchoicemakesabigdifferencetotheresults.Herethetopoftherangeisused:32°C.Theareaswheretheprojecteddailymaximumtemperaturerangecrossesthetemperaturethresholdforcocoa,andwhereitisabovethethresholdforthreeRCPsandthreetimeperiodsareshowninFigure4.

Lookingatthisplotintermsofclimatevulnerabilityandrisk,theareasingreen(temperaturerangebelowthethreshold)canbeinterpretedasbeingfairlylowriskofbeinglimitedbytemperature,areasinorangeaspotentiallyatrisk,andredareasasbeingveryhighriskofbeingunsuitable.IntheGuadalcanalPlainarea,theeffectoftheemissionsscenarioisveryimportant.Underaverylowscenario(RCP2.6),GuadalcanalPlainispossiblytoowarmifthehighendofthemodelrangeisfollowed.Undertheotherscenarios(RCP4.5andRCP8.5),temperaturecouldbecomeanimportantlimitingfactortococoagrowingby2050,andcertainlyby2090,evenifthelowerendofthe


RCP2.6,2030 (+0.4to0.9ºC)

Monthly Tmax over 32 ºC

RCP4.5,2030 (+0.4to1.0ºC)

RCP8.5,2030 (+0.5to1.0ºC)

RCP2.6,2050 (+0.6to1.2ºC)

RCP4.5,2050 (+0.7to1.4ºC)

RCP8.5,2050 (+1.0to1.9ºC)

RCP2.6,2090 (+0.4to1.2ºC)

RCP4.5,2090 (+1.0to2.1ºC)

RCP8.5,2090 (+2.0to4.0ºC)

Figure 4. The annual average daily maximum temperature of Guadalcanal: categorisation of regions in relation to the 32 °C threshold for growing cocoa in 2030, 2050 and 2090 under different RCPs (projected ranges of changes in temperature noted in brackets). Green shows the range is all below threshold, orange shows that the range crosses the threshold, and red shows the range is all above the threshold. Dashed line indicates the Guadalcanal Plain.

modelrangeisfollowed.Thisshowsthatthereisaclearbenefitofmitigationbyreducingemissions–itmakesthedifferencebetweenapossibleriskandafairlydefiniteriskthatthecocoafarmingindustry in Solomon Islands becomes unviableinthefuture.Also,theriskpriorto2050appearslow,soitseemsthattemperatureisunlikelytobealimitingfactortotheindustryinthenearfuture.

Thistemperatureanalysisalsoprovidesinsightsintothepotentialadaptationoptionsfortheindustrylaterinthecentury,notingmoreelevatedareasarelesslikelytobecometoowarmforgrowingcocoa.Possibleadaptationresponsesmaythereforeinclude:• IdentifyingwhethercocoaproductionintheGuadalcanalPlaincouldbeexpandedfurtheruptheadjacentslopesofthecatchmenttofollowthechangeintheoptimaltemperaturegrowingenvelope

• Investigatingchangesthroughselectivebreedingtothecropvarietycoulddevelophighertemperature tolerance strains of cocoaforproductioninexistingfarm areas of Guadalcanal Plain.

B. RainfallThereisarangeofprojectedchangestoaverageannualrainfallinSolomonIslands–fromlittlechangethroughtoincrease(AustralianBureauofMeteorologyandCSIRO2014).ThisrangeofpossibilitiesmeansthatthereisalsouncertaintyaboutwhethertheriskofGuadalcanalbecomingtoowetwillincreaseordecrease.Thisuncertaintyisseenasadecreaseinthegreenandredareas,butanincreaseintheorangeareaintheplotsthroughtimeandforhigherRCPs(Figure5).

Figure 5. Average annual rainfall of Guadalcanal: categorisation of regions in relation to the 1250–3000 mm limits for growing cocoa in 2050 and 2090 under different RCPs (projected ranges of changes in rainfall noted in brackets). Green shows the range is all below threshold, orange shows that the range crosses the threshold, and red shows the range is all above the threshold. Dashed line indicates the Guadalcanal Plain.

RCP2.6,2030 (-1to+8%)

Annual rainfall over 300mm

RCP4.5,2030 (-2to+9%)

RCP8.5,2030 (-1to+7%)

RCP2.6,2050 (-1to+7%)

RCP4.5,2050 (-4to+9%)

RCP8.5,2050 (-3to+9%)

RCP2.6,2090 (-1to+12%)

RCP4.5,2090 (-4to+10%)

RCP8.5,2090 (-7to+20%)


Theincreaseintheorangeareashowsthatagreaterareamaybecometoowetortoodryforgrowingcocoa,butthereisalackofagreementintheprojectionsonthis.TheregionofGuadalcanalPlainwherecocoaisnowgrownshowsrelativelylowerpotentialriskthanotherareasofSolomonIslands(i.e.whichremainsgreen),exceptin2090andespeciallyunderRCP8.5.Thissuggeststhataverageannualrainfallmightnotbecomealimitingfactorinfuture.

Itmustbeacknowledgedthatrainfallprojectionshavelowerconfidencecomparedtotemperatureprojections,sochangesoutsidetheprojectedrangearepossible.Thismeansthatspecificadaptationstrategieswithlimitedflexibilitytodealwiththisuncertaintyinclimateriskareprobablynotappropriate,rathermoreflexiblestrategiesarepreferredtogetherwithongoingmonitoringandassessmentoftheissues.

C. Fungal diseaseRainfallprojectionsareuncertainbutsuggestthataverageannualrainfallmaystay similar to today or may increase inthelongtermbutislesslikelytodecreasestrongly.SinceGuadalcanalPlainalreadyexperiencesrisksfromfungaldiseasepartlyduetoexistingrainfallpatterns,thentheserainfallprojectionssuggestthatthisriskisverylikelytoremain,andpossiblycouldbecomemoreintenseoraffectmoreareasinthefuture.Thismeansthattheindustryislikelytocontinueneedingtomanagefungaldiseaseusingtechniquessuchaspruningintothefuture,especiallyinwetyears.

D. Extreme rainfall, flooding and dry spellsAtthedryendofrainfallprojectionsunderahighemissionsscenarioby2090,therecouldbeasmallincreaseintheaverageoccurrenceofdryspells(runsofmorethanthreemonthsbelow100mmrainfall).UnderthesecircumstancestheaverageclimatecouldfeaturetheseconditionsinasmallareainwesternGuadalcanalPlain(notshown),butthisisonlyapossibilityunderthestrongestchangecase,anditisnotaverylikelycase.

Theresultsoftheaverageclimatedon’tshowtheeffectofbadyears,whichneedsananalysisofvariabilityincludingdryyearsandwetyears,andaccountingforprojectedchangestorainfallvariabilityaswellaschangetotheaverage.DatafromAustralianBureauofMeteorologyandCSIRO(2014)showsthatfortheSolomonIslandsmeteorologicaldrought(anindexbasedonlyonrainfall)isprojectedto decrease in frequency and duration, withpossiblytheexceptionofextremedroughts,whichmightincrease.Thissuggeststhattheprojectedchangeinaverageconditionsisnotlikelytoleadtoanincreaseinrisktococoagrowingfromdrymonthsbutincreasesinextremeeventsorextremedroughtyearsmayhaveimportantimpacts.ThefrequencyandintensityofextremerainfalleventsareprojectedtoincreaseintheSolomonIslands(AustralianBureauofMeteorologyandCSIRO2014).Extremewetdaysareprojectedtoincrease,wherethe1-in-20-yeareventcouldbecomea1-in-9-yeareventundermoderateclimatechange(RCP2.6),ora1-in-4-yeareventunderaworst-caseemissionsscenario(RCP8.5)by2090.Undertheseconditions,cocoafarmersinGuadalcanalPlainwilllikelyexperienceincreasedriskfromlocalisedfloodinganddamagetoplantflowering.

STEP 8 Communicate climate change informationThefirststepofcommunicatingtheresultsofthiscasestudyistoidentifytheintendedaudience.Forthisassessment,theprimaryaudienceisMAL.ThesecondaryaudienceisthefarmersandindustrystakeholdersthatMALdealswith.

Themaincommunicationproducttopresenttheassessmentresultsisthiscasestudyreport,intendedprimarilyforMAL.AfactsheetisalsobeingpreparedthatMALcanuseintheircommunicationwithfarmersandindustrystakeholders.

Resultsofthisassessmentmayalsobepresentedinotherways,asappropriate,including:• Briefingstodecisionmakers,presentationsatmeetingsand conferences

•Mediareleases• Scientificpaperoutliningtheresults(toaddscientificcredibilitytothefindings)

Inaddition,theresultsofthispreliminaryassessment can be used as input to a full,moredetailedandcomprehensiveriskassessmenttobeundertakenforthecocoaorbroaderagriculturalsectorin Solomon Islands at some future date.


REFERENCES

AustralianBureauofMeteorologyandCSIRO(2014).ClimateVariability,ExtremesandChangeintheWesternTropicalPacific:NewScienceandUpdatedCountryReports.Pacific-AustraliaClimateChangeScienceandAdaptationPlanningProgramTechnicalReport.AustralianBureauofMeteorologyandCommonwealthScientificandIndustrialResearchOrganisation (CSIRO),Melbourne,Australia (www.pacificclimatechangescience.org)

CSIROandSPREP(2017)DevelopingClimateChangeInformationforthePacific:GuidanceMaterialtoRaiseAwareness andFacilitateSectoralDecision-MakingUsingScience-BasedClimateChangeinformationandServices.CommonwealthScientificandIndustrialResearchOrganisation(CSIRO)andSecretariat forthePacificRegionalEnvironmentProgram(SPREP),Melbourne,Australia(www.pacificclimatechangescience.org)

Fick,S.E.andHijmans,R.J.(2017).WorldClim2:new1-kmspatialresolutionclimatesurfacesforgloballandareas.International Journal of Climatology 37:4302–4315.

Grose,M.R.andco-authors(2014).AssessmentoftheCMIP5globalclimatemodelsimulationsofthewesterntropicalPacificclimatesystemandcomparisontoCMIP3.International Journal of Climatology34:3382–3399.

Läderach,P.,Martinez-Valle,A.,Schroth,G.andCastro,N.(2013).Predictingthefutureclimaticsuitabilityforcocoafarmingoftheworld’sleadingproducercountries,GhanaandCôted’Ivoire.Climatic Change119:841–854.

McGregor,A.,Bourke,R.M.,Lebot,V.andTaylor,M.(2016).Chapter5.Vulnerabilityofexportcommoditiestoclimatechange.InVulnerability of Pacific Island Agriculture and Forestry to climate change.(Eds)M.Taylor,A.McGregorandB.Dawson.SecretariatofthePacificCommunity(SPC)NoumeaCedex,NewCaledonia:239–294.

Taylor,M.,McGregor,A.andDawson,B.(2016)VulnerabilityofPacificIslandAgricultureandForestrytoClimateChange.SecretariatofthePacificCommunity(SPC)NoumeaCedex,NewCaledonia.




www.pacificclimatechangescience.org

For more information contact the Pacific Met Desk PartnershipEmail: [email protected] Telephone: +685 21929 Visit: www.sprep.org

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Climate change impacts cocoa farming Solomons WEB · 2018-04-06 · Climate change impacts and risks for cocoa farming in Guadalcanal Plain, Solomon Islands 5 Process overview This