1ARAPIDRESPONSEASSESSMENTTHEROLEOFHEALTHYOCEANSINBINDINGCARBONBLUECARBONDisclaimerThecontentsofthisreportdonotnecessarilyreflecttheviewsorpoliciesofUNEPorcon-tributoryorganisations.ThedesignationsemployedandthepresentationsdonotimplytheexpressionsofanyopinionwhatsoeveronthepartofUNEPorcontributoryorganisationsconcerningthelegalstatusofanycountry,territory,city,companyorareaoritsauthority,orconcerningthedelimitationofitsfrontiersorboundaries.UNEPpromotesenvironmentallysoundpracticesgloballyandinitsownactivities.Thisreportisprintedon100%recycledpaper,usingvegetable-basedinksandothereco-friendlypractices.OurdistributionpolicyaimstoreduceUNEP’scarbonfootprint.Thisreportisproducedasaninter-agencycollaborationbetweenUNEP,FAOandIOC/UNESCO,withspecialinvitedcontributionofDr.CarlosM.Duarte,InstitutMediter-ránid’EstudisAvançats,Spain.Nellemann,C.,Corcoran,E.,Duarte,C.M.,Valdés,L.,DeYoung,C.,Fonseca,L.,Grimsditch,G.(Eds).2009.BlueCarbon.ARapidResponseAssessment.UnitedNationsEnvironmentProgramme,GRID-Arendal,www.grida.noISBN:978-82-7701-060-1PrintedbyBirkelandTrykkeriAS,NorwayChristianNellemann(Editorinchief)EmilyCorcoranCarlosM.DuarteLuisValdésCassandraDeYoungLucianoFonsecaGabrielGrimsditchARAPIDRESPONSEASSESSMENTTHEROLEOFHEALTHYOCEANSINBINDINGCARBONBLUECARBON45Theburningoffossilfuelsisgeneratinglevelsofwhatonemightterm‘brown’and‘black’carbonintheatmosphereandunlesscheckedmaytakeglobaltemperaturesaboveathresholdof2˚C.Dramaticreductionsarepossiblebyacceleratingenergyefficiencymeasuresandboostingthedeploymentofcleanerenergygenerationandrenewablessuchassolar,windandgeo-thermal.Overthepastfewyearssciencehasbeenilluminatingothersourcesofemissionsandotheropportunitiesforaction.Deforestationforexamplenowaccountsforcloseto20%ofglobalgreenhousegasemissions.Inamatterofweeks,governmentswillmeetinCopenhagenwherethereisanurgencytoSealtheDealonanewandforward-lookingagreement.Partofthatpackageofmeasuresneedstoinclude‘green’carbon–thecarbonstoredintheglobe’sforestsandtheirsoilsandespeciallyinthetropics.Financingapart-nershipforReducedEmissionsfromDeforestationandforestDegradation(REDD)canplayanimportantroleinkeepingthatgreencarbonwhereitbelongswhilealsoassistingthedevelop-mentandemploymentobjectivesofdevelopingeconomiesbygivinganeconomicvaluetothesevitalecosystemservices.Scienceisnowalsotellingusthatweneedtourgentlyaddressthequestionof‘blue’carbon.Anestimated50%ofthecarbonintheatmospherethatbecomesboundor‘sequestered’innaturalsystemsiscycledintotheseasandoceans–anotherexampleofnature’singenuityfor‘carboncaptureandstorage’.However,aswithforestswearerapidlyturningthatbluecarbonintobrowncarbonbyclearinganddamagingtheverymarineecosystemsthatareabsorbingandstoringgreenhousegasesinthefirstplace.Thisinturnwillaccelerateclimatechange,puttingatriskcom-munitiesincludingcoastalonesalongwithothereconomically-importantassetssuchascoralreefs;freshwatersystemsandmarinebiodiversityaswellas‘hard’infrastructurefromportstopower-stations.Targetedinvestmentsinthesustainablemanagementofcoastalandmarineecosystems–thenaturalinfrastructure–alongsidetherehabilitationandrestorationofdamagedanddegradedones,couldproveaverywisetransac-tionwithinordinatereturns.Thisreport,producedbysomeoftheworld’sleadingscientistsandincollaborationwiththeFAOandIOC-UNESCO,findsthatthemostcrucial,climate-combatingcoastalecosystemscoverlessthan0.5%oftheseabed.Buttheyaredisappearingfasterthananythingonlandandmuchmaybelostinacoupleofdecades.Theseareas,coveringfeaturessuchasmangroves,saltmarshesandseagrasses,areresponsibleforcapturingandstoringuptosome70%ofthecarbonpermanentystoredinthemarinerealm.Ifwearetotackleclimatechangeandmakeatransitiontoare-sourceefficient,GreenEconomy,weneedtorecognizetheroleandthecontributionofallthecoloursofcarbon.Bluecarbon,foundandstoredawayintheseasandoceans,isemergingasyetanotheroptiononthepaletteofpromisingopportunitiesandactions,onethatcanassistindeliveringabrightratherthanadarkbrownandultimatelyblackfuture.AchimSteinerUNUnder-SecretaryGeneralandExecutiveDirector,UNEPPREFACEThemostcrucial,climate-combatingcoastalecosystemsaredisappearingfasterthananythingonlandandmuchmaybelostinacoupleofdecades.Iftheworldistodecisivelydealwithclimatechange,everysourceofemissionsandeveryoptionforreducingtheseshouldbescientificallyevaluatedandbroughttotheinterna­tionalcommunity’sattention.6EXECUTIVESUMMARYTheobjectiveofthisreportistohighlightthecriticalroleoftheoceansandoceanecosys­temsinmaintainingourclimateandinassistingpolicymakerstomainstreamanoceansagendaintonationalandinternationalclimatechangeinitiatives.Whileemissions’re­ductionsarecurrentlyatthecentreoftheclimatechangediscussions,thecriticalroleoftheoceansandoceanecosystemshasbeenvastlyoverlooked.Outofallthebiologicalcarbon(orgreencarbon)capturedintheworld,overhalf(55%)iscapturedbymarinelivingorgan-isms–notonland–henceitiscalledbluecarbon.Continu-allyincreasingcarbondioxide(CO2)andothergreenhousegasemissionsarecontributingtoclimatechange.Manycountries,includingthosegoingthroughperiodsofrapidgrowth,areincreasingtheiremissionsofbrownandblackcarbon(suchasCO2andsoot)asaresultofrapideconomicdevelopment.Alongwithincreasedemissions,naturalecosystemsarebeingdegraded,reducingtheirabilitytoabsorbCO2.Thislossofca-pacityisequivalenttoonetotwotimesthatoftheannualemis-sionsfromtheentireglobaltransportsector.Risinggreenhousegasesemissionsareproducingincreasingimpactsandchangesworldwideonweatherpatterns,foodpro-duction,humanlivesandlivelihoods.Foodsecurity,social,eco-nomicandhumandevelopmentwillallbecomeincreasinglyjeopardizedinthecomingdecades.MaintainingorimprovingtheabilityofforestsandoceanstoabsorbandburyCO2isacrucialaspectofclimatechangemitigation.Thecontributionofforestsinsequesteringcarboniswellknownandissupportedbyrelevantfinancialmecha-nisms.Incontrast,thecriticalroleoftheoceanshasbeenover-looked.Theaimofthisreportistohighlightthevitalcontribu-tionoftheoceansinreducingatmosphericCO2levelsthroughsequestrationandalsothroughreducingtherateofmarineandcoastalecosystemdegradation.ItalsoexplorestheoptionsfordevelopingafinancialstructureformanagingthecontributionoceansmaketoreducingCO2levels,includingtheeffective-nessofanoceanbasedCO2reductionscheme.Oceansplayasignificantroleintheglobalcarboncycle.Notonlydotheyrepresentthelargestlong-termsinkforcarbonbuttheyalsostoreandredistributeCO2.Some93%oftheearth’sCO2(40Tt)isstoredandcycledthroughtheoceans.Theocean’svegetatedhabitats,inparticularmangroves,saltmarshesandseagrasses,cover<0.5%oftheseabed.Theseformearth’sbluecarbonsinksandaccountformorethan50%,perhapsasmuchas71%,ofallcarbonstorageinoceansediments.Theycompriseonly0.05%oftheplantbiomassonland,butstoreacomparableamountofcarbonperyear,andthusrankamongthemostintensecarbonsinksontheplanet.Bluecarbonsinksandestuariescaptureandstorebetween235–450TgCeveryyear–ortheequivalentofuptohalfoftheemissionsfromtheentireglobaltransportsector,estimatedataround1,000TgCyr–1.Bypreventingthefurtherlossanddegradationoftheseecosystemsandcatalyzingtheirrecovery,wecancontributetooffsetting3–7%ofcurrentfossilfuelemis-sions(totaling7,200TgCyr–1)intwodecades–overhalfofthatprojectedforreducingrainforestdeforestation.Theeffect7wouldbeequivalenttoatleast10%ofthereductionsneededtokeepconcentrationsofCO2intheatmospherebelow450ppm.Ifmanagedproperly,bluecarbonsinks,therefore,havethepo-tentialtoplayanimportantroleinmitigatingclimatechange.Therateoflossofthesemarineecosystemsismuchhigherthananyotherecosystemontheplanet–insomeinstancesuptofourtimesthatofrainforests.Currently,onaverage,be-tween2–7%ofourbluecarbonsinksarelostannually,asev-en-foldincreasecomparedtoonlyhalfacenturyago.Ifmoreactionisnottakentosustainthesevitalecosystems,mostmaybelostwithintwodecades.Haltingdegradationandrestoringboththelostmarinecarbonsinksintheoceansandslowingdeforestationofthetropicalforestsonlandcouldresultinmitigatingemissionsbyupto25%.Sustainingbluecarbonsinkswillbecrucialforecosystem-basedadaptationstrategiesthatreducevulnerabilityofhu-mancoastalcommunitiestoclimatechange.Haltingthede-clineofoceanandcoastalecosystemswouldalsogenerateeconomicrevenue,foodsecurityandimprovelivelihoodsinthecoastalzone.Itwouldalsoprovidemajoreconomicanddevelopmentopportunitiesforcoastalcommunitiesaroundtheworld,includingextremelyvulnerableSmallIslandDe-velopingStates(SIDS).Coastalwatersaccountforjust7%ofthetotalareaoftheocean.Howevertheproductivityofecosystemssuchascoralreefs,andthesebluecarbonsinksmeanthatthissmallareaformsthebasisoftheworld’sprimaryfishinggrounds,sup-plyinganestimated50%oftheworld’sfisheries.Theyprovidevitalnutritionforcloseto3billionpeople,aswellas50%ofanimalproteinandmineralsto400millionpeopleoftheleastdevelopedcountriesintheworld.Thecoastalzones,ofwhichthesebluecarbonsinksarecen-tralforproductivity,deliverawiderangeofbenefitstohu-mansociety:filteringwater,reducingeffectsofcoastalpol-lution,nutrientloading,sedimentation,protectingthecoastfromerosionandbufferingtheeffectsofextremeweatherevents.CoastalecosystemserviceshavebeenestimatedtobeworthoverUS$25,000billionannually,rankingamongthemosteconomicallyvaluableofallecosystems.Muchofthedegradationoftheseecosystemsnotonlycomesfromunsus-tainablenaturalresourceusepractices,butalsofrompoorwatershedmanagement,poorcoastaldevelopmentpracticesandpoorwastemanagement.Theprotectionandrestorationofcoastalzones,throughcoordinatedintegratedmanage-mentwouldalsohavesignificantandmultiplebenefitsforhealth,labourproductivityandfoodsecurityofcommunitiesintheseareas.Thelossofthesecarbonsinks,andtheircrucialroleinman-agingclimate,health,foodsecurityandeconomicdevelop-mentinthecoastalzones,isthereforeanimminentthreat.Itisoneofthebiggestcurrentgapstoaddressunderclimatechangemitigationefforts.Ecosystembasedmanagementandadaptationoptionsthatcanbothreduceandmitigateclimatechange,increasefoodsecurity,benefithealthandsubsequentproductivityandgeneratejobsandbusinessareofmajorimportance.Thisiscontrarytotheperceptionthatmitigationandemissionreductionisseenasacostandnotaninvestment.Improvedintegratedmanagementofthecoastalandmarineenvironments,includingprotectionandrestorationofourocean’sbluecarbonsinks,providesoneofthestrongestwin-winmitigationeffortsknowntoday,asitmayprovidevalue-addedbenefitswellinexcessofitscosts,buthasnotyetbeenrecognizedintheglobalprotocolsandcarbontradingsystems8Establishaglobalbluecarbonfundforprotectionandmanagementofcoastalandmarineecosys-temsandoceancarbonsequestration.a.Withininternationalclimatechangepolicyinstruments,cre-atemechanismstoallowthefutureuseofcarboncreditsformarineandcoastalecosystemcarboncaptureandeffectivestor-ageasacceptablemetricsbecomeavailable.Bluecarboncouldbetradedandhandledinasimilarwaytogreencarbon–suchasrainforests–andenteredintoemissionandclimatemitiga-tionprotocolsalongwithothercarbon-bindingecosystems;b.Establishbaselinesandmetricsforfutureenvironmentallysoundoceancarboncaptureandsequestration;c.Considertheestablishmentofenhancedcoordinationandfundingmechanisms;d.Upscaleandprioritizesustainable,integratedandecosys-tem-basedcoastalzoneplanningandmanagement,especiallyinhotspotswithinthevicinityofbluecarbonsinkstoincreasetheresilienceofthesenaturalsystemsandmaintainfoodandlivelihoodsecurityfromtheoceans.Immediatelyandurgentlyprotectatleast80%ofremainingseagrassmeadows,saltmarshesandmangroveforests,througheffectivemanagement.Futurefundsforcarbonsequestrationcancontributetomain-tainingmanagementandenforcement.Initiatemanagementpracticesthatreduceandre-movethreats,andwhichsupporttherobustrecoverypotentialinherentinbluecarbonsinkcommunities.Maintainfoodandlivelihoodsecurityfromtheoceansbyimplementingcomprehensiveandinte-gratedecosystemapproachesaimingtoincreasetheresilienceofhumanandnaturalsystemstochange.Implementwin-winmitigationstrategiesintheocean-basedsectors,includingto:a.Improveenergyefficiencyinmarinetransport,fish-ingandaquaculturesectorsaswellasmarine-basedtourism;b.Encouragesustainable,environmentallysoundoceanbasedenergyproduction,includingalgaeandseaweed;c.Curtailactivitiesthatnegativelyimpacttheocean’sabilitytoabsorbcarbon;d.Ensurethatinvestmentforrestoringandprotectingtheca-pacityofocean’sbluecarbonsinkstobindcarbonandprovidefoodandincomesisprioritizedinamannerthatalsopromotesbusiness,jobsandcoastaldevelopmentopportunities;e.Catalyzethenaturalcapacityofbluecarbonsinkstoregener-atebymanagingcoastalecosystemsforconditionsconducivetorapidgrowthandexpansionofseagrass,mangroves,andsaltmarshes.15432Inordertoimplementaprocessandmanagethenecessaryfundsfortheprotection,managementandrestorationofthesecrucialoceancarbonsinks,thefollowingoptionsareproposed:KEYOPTIONS:9PREFACEEXECUTIVESUMMARYINTRODUCTIONEMISSIONSANDSEQUESTRATION–THEBINDINGOFCARBONBLUEPLANET:OCEANSANDCLIMATEBLUECARBON–THEROLEOFOCEANSASCARBONSINKSTHEWORLD’SOCEANCARBONSINKSINRAPIDDECLINEOCEANS’BLUECARBONSINKSANDHUMANWELLBEINGECOSYSTEMBASEDADAPTATIONANDMITIGATIONPOLICYOPTIONSGLOSSARYACRONYMSCONTRIBUTORSREFERENCESCONTENTS561115233545516165707273741011OfalltheGreencarboncapturedannuallyintheworld,thatisthecarboncapturedbyphotosyntheticactivity,overhalf(55%)iscapturedbymarinelivingorganisms(Falkow­skietal.,2004;Arrigo,2005;González,etal.,2008;Bowler,2009;Simonetal.,2009).Thisoceaniccarboncycleisdominatedbymicro-,nano-,andpicoplankton,includingbacteriaandarchaea(Burkill,2002).Eventhoughplantbiomassintheoceansisonlyafractionofthatonland,just0.05%,itcyclesalmostthesameamountofcarboneachyear(Bouillonetal.,2008;Houghton,2007);thereforerepresentingextremelyefficientcarbonsinks.However,whileincreasingeffortsarebeingmadetoslowdegradationonland,suchasthroughprotectionofrainforestsasameanstomitigateclimatechange,theroleofmarineecosystemshastodatebeenlargelyignored.INTRODUCTIONKnowledgeoftheroleofnaturalecosystemsincapturingCO2isanincreasinglyimportantcomponentindevelopingstrate-giestomitigateclimatechange.Lossesanddegradationofnaturalecosystemscompriseatleast20–30%ofourtotalemis-sions(UNEP,2008a;2009).Whileoverallemissionsfromtheburningoffossilfuelsneedstobeseverelyreduced,mitigatingclimatechangecanalsobeachievedbyprotectingandrestoringnaturalecosystems(Trumperetal.,2009).Evenfromanar-rowperspectiveofemissionreductionsalone,theycanplayasignificantrole.Assteepreductionoffossilfuelemissionsmaycompromisethedevelopmentpotentialofsomecountries,itiscriticalthatoptionsareidentifiedthatcanhelpmitigateclimatechangewithneutralorevenpositiveimpactsondevelopment.Itisthereforeabsolutelycriticaltoidentifythosenaturalecosys-temsthatcontributemosttobindingourincreasingemissionsofcarbonorCO2andenhancethisnaturalcapacity(Trumperetal.,2009).Someoftheseareintheoceans.Some93%oftheearth’scarbondioxide–40TtCO2–isstoredintheoceans.Inaddition,oceanscycleabout90GtofCO2yr–1(Gonzálezetal.,2008),andremoveover30%ofthecarbonreleasedtotheatmosphere.Resilientaquaticecosystemsnotonlyplayacrucialroleinbind-ingcarbon,theyarealsoimportanttoeconomicdevelopment,foodsecurity,socialwellbeingandprovideimportantbuffersagainstpollution,andextremeweatherevents.Coastalzonesareofparticularimportance,withobviousrelationsandimpor-tancetofisheries,aquaculture,livelihoodsandsettlements(KayandAlder,2005)–over60%oftheworld’spopulationissettledinthecoastalzone(UNEP,2006,2008b).Formanycoastaldevelopingcountries,thecoastalzoneisnotonlycrucialforthewellbeingoftheirpopulations,itcouldalso,asdocumentedinthisreport,provideahighlyvaluableglobalresourceforcli-matechangemitigationifsupportedadequately.Thisreportexploresthepotentialformitigatingtheimpactsofclimatechangebyimprovedmanagementandprotectionofmarineecosystemsandespeciallythevegetatedcoastalhabitat,orbluecarbonsinks.12--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------10207501580610CoalfieldsOilandgasfieldsAtmosphereSoilBiosphereLandusechangeRivers0.8909212160601.50.5896.1Source:IPCC.3000300CarbonfluxesandstocksFluxes:GigatonnesofCperyearStorage:GigatonnesofC1020813Carboncycle------------15010203810065050DeepoceanDissolvedorganicCLabiledissolvedorganicCSedimentsOceansurfaceMarinebiota34660.24050100Figure1:CarbonCycle.Oceansarecrucialintheglobalcarboncycle.Itwasherewherelifefirstevolved;theyarethesourceofourwealthanddevelopment.ThelivingoceanscaptureoverhalfofalltheGreencarbon–thecar-bonboundbylivingorganismsthroughphotosynthesis.UnitsofCarbonused.ThisreportwilluseTgC,butread-erswillalsoseevaluesforCandCO2,providedinawiderangeofformats.Thefollowinginformationmayassistinwiderreading.Definition:MeasuringCarbon1km2=100ha1ton=2,240lbs1(metric)ton=1,000kgor1x106gBluecarbonsinkscaptureCO2throughphotosynthesisfromtheairandwaterandstoreitascarbon.TherateofconvertingCtoCO2is44/12;i.e.1atonofCisequivalentto3.67tCO2NameOnethousandOnemillionOnebillionOnetrillionFactor10310610910121015Symbolk(Kilo)M(Mega)G(Giga)T(Tera)P(Peta)1415Anthropogenicclimatechangeiscausedbytherisingcontentofgreenhousegasesandparticlesintheatmosphere.Firstlybytheburningoffossilfuels,releasinggreenhousegasessuchasCO2,(“browncarbon”)anddustparticles(partof“blackcarbon”);secondlybyemissionsfromclearingnaturalvegetation,forestfiresandagriculturalemissions,in­cludingthosefromlivestock;andthirdly–bythereducedabilityofnaturalecosystemstobindcarbonthroughphotosynthesisandstoreit–socalledgreencarbon(Trumperetal.,2009).TheuptakeofCO2intoareservoiroverlong(severaldecadesorcenturies)timescales,whethernaturalorartificialiscalledcarbonsequestration(Trumperetal.,2009).EMISSIONSANDSEQUESTRATION–THEBINDINGOFCARBONClimateChangehasdrivenwidespreadappreciationofatmo-sphericCO2asthemaingreenhousegasandoftheroleofan-thropogenicCO2emissionsfromenergyuseandindustryinaffectingtemperaturesandtheclimate–werefertotheseemis-sionsas“browncarbon”forgreenhousegasesand“blackcar-bon”forparticlesresultingfromimpurecombustion,suchassootanddust.TheEmissionsTradingSystemoftheEuropeanUnion(EU-ETS)isa“black-browncarbon”systemasitdoesnotincorporateforestrycredits.TheKyotoProtocol’sCleanDevel-opmentMechanism(CDM)doesinprincipleincludeforestrycredits,butdemand(intheabsenceofalinkingdirectiveanddemandfromtheEU-ETS)andpriceshavealwaysbeentoolowtoencouragesuccess,soCDMhasalsobecome,forallpracticalpurposes,another“blackcarbon”mechanism.Terrestrialcarbonstoredinplantbiomassandsoilsinforestland,plantations,agriculturallandandpasturelandisoftencalled“greencarbon”.Theimportanceof“greencarbon”isbeingrecognizedthroughanticipatedagreementattheUnitedNationsFrameworkConventiononClimateChangeConferenceoftheParties(COP)inCopenhagen,December2009,whichincludesforestcarbon–throughvariousmechanisms,betheyREDDandafforestation,REDD-Plus,and/orothers(e.g.‘ForestCarbonforMitigation’).Theworld’soceansbindanestimated55%ofallcarboninlivingor-ganisms.Theocean’sbluecarbonsinks–particularlymangroves,marshesandseagrassescaptureandstoremostofthecarbonburiedinmarinesediments.Thisiscalled“bluecarbon”.Theseecosystems,however,arebeingdegradedanddisappearatrates5–10timesfasterthanrainforests.Together,byhaltingdegradationof“green”and“blue”carbonbindingecosystems,theyrepresentanemissionreductionequivalentto1–2timesthatoftheentireglobaltransportsector–oratleast25%ofthetotalglobalcarbonemissionreductionsneeded,withadditionalbenefitsforbiodiver-sity,foodsecurityandlivelihoods.Itisbecomingincreasinglyclearthataneffectiveregimetocontrolemissionsmustcontroltheen-tire“spectrum”ofcarbon,notjustone“colour”.Intheabsenceof“GreenCarbon”,biofuelcroppingcanbecomeincentivized,andcanleadtocarbonemissionsifitisnotdonecor-rectly.Theconversionofforests,peatlands,savannasandgrass-landstoproducefood-cropbasedbiofuelsinBrazil,SoutheastAsiaandtheUnitedStatescreatesabiofuelcarbondebtbyemitting14to420timesmoreCO2thantheannualreductionsingreenhousegasesthesebiofuelsprovidebyreplacingfossilfuels.Incontrast,biofuelsproducedfromwastebiomassandcropsgrownonde-gradedagriculturallanddonotaccrueanysuchcarbondebt.Factbox1.Thecoloursofcarbon:Brown,Black,BlueandGreen16BROWN,BLACK,GREENANDBLUECARBONglobalwarmingoverthepastcentury.Blackcarbontendstoremainintheatmospherefordays-weeks(HansenandNaza-rento,2004)whereasCO2remainsintheatmosphereforap-prox100years(IGSD,2009).ThetotalCO2emissionsofareestimatedtobebetween7,200TgCyr–1,and10,000TgCyr–1(Trumperetal.,2009),andtheamountofcarbonintheatmosphereisincreasingbyap-proximately2,000TgCyr–1(Houghton,2007).GREENCARBONGreencarboniscarbonremovedbyphotosynthesisandstoredintheplantsandsoilofnaturalecosystemsandisavitalpartoftheglobalcarboncycle.Sofar,however,ithasmainlybeencon-sideredintheclimatedebateinterrestrialecosystems,thoughtheissueofmarinecarbonsequestrationhasbeenknownforatleast30years.Asinkisanyprocess,activityormechanismthatremovesagreenhousegas,anaerosoloraprecursorofagreenhousegasoraerosolfromtheatmosphere.NaturalsinksforCO2areforexampleforests,soilsandoceans.Unlikemanyplantsandmostcrops,whichhaveshortlivesorreleasemuchoftheircarbonattheendofeachseason,forestbio-massaccumulatescarbonoverdecadesandcenturies.Further-more,forestscanaccumulatelargeamountsofCO2inrelativelyshortperiods,typicallyseveraldecades.Afforestationandrefores-tationaremeasuresthatcanbetakentoenhancebiologicalcar-bonsequestration.TheIPCCcalculatedthataglobalprogrammeinvolvingreduceddeforestation,enhancednaturalregenerationoftropicalforestsandworldwidere-afforestationcouldseques-Figure3:Worldgreenhouseemissionbysector.Alltransportaccountsforapproximately13.5%ofthetotalemissions,whiledeforestationaccountsforapproximately18%.However,esti-matesofthelossofmarinecarbon-bindingecosystemshavepreviouslynotbeenincluded.Figure2:Projectedgrowthinenergydemandincomingdecades.Brownandblackcarbonemissionsfromfossilfuels,biofuelsandwoodburningaremajorcontributorstoglobalwarming.Blackcarbonemissionshavealargeeffectonradiationtrans-missioninthetroposphere,bothdirectlyandindirectlyviaclouds,andalsoreducethesnowandicealbedo.Blackcarbonisthoughttobethesecondlargestcontributortoglobalwarming,nexttobrowncarbon(thegases).Thus,reduc-ingblackcarbonemissionrepresentsoneofthemostefficientwaysformitigatingglobalwarmingthatweknowtoday.Blackcarbonenterstheoceanthroughaerosolandriverdeposi-tion.Blackcarboncancompriseupto30%ofthesedimentaryorganiccarbon(SOC)insomeareasofthedeepsea(MasielloandDruffel,1998)andmayberesponsiblefor25%ofobservedOtherrenewables1980199020002010202020303690OilActualandprojectedenergydemandGigatonnesofoilequivalentHydropowerNote:Allstatisticsrefertoenergyinitsoriginalform(suchascoal)beforebeingtransformedintomoreconvenientenergy(suchaselectricalenergy).Source:InternationalEnergyAgency(IEA),WorldEnergyOutlook2008.ProjectionsGasCoalBiomassNuclear151217LandusechangeAgricultureWasteTransportationElectricity&heatIndustryFugitiveemissionsOtherfuelcombustionCarbondioxide(CO2)77%(CH4)14%(N2O)8%MethaneNitrousoxideHFCs,PFCs,SF61%AgriculturesoilsLivestock&manureRicecultivationOtheragricultureLandfillsWastewater,otherwasteAgriculturalenergyuseT&DlossesCoalminingOil/gasextraction,Refining&processingDeforestationAfforestationReforestationHarvest/ManagementOtherCementOtherindustryChemicalsAluminium/Non-ferrousmetalsFood&tobaccoPulp,paper&printingMachineryRoadAirRail,ship&othertransportUnallocatedfuelcombustionCommercialbuildingsResidentialbuildingsIron&steelSectorEnduse/activityGasAlldataisfor2000.AllcalculationsarebasedonCO2equivalents,using100-yearglobalwarmingpotentialsfromtheIPCC(1996),basedonatotalglobalestimateof41755MtCO2equivalent.Landusechangeincludesbothemissionsandabsorptions.Dottedlinesrepresentflowsoflessthan0.1%percentoftotalGHGemissions.Source:WorldResourcesInstitute,ClimateAnalysisIndicatorTool(CAIT),NavigatingtheNumbers:GreenhouseGasDataandInternationalClimatePolicy,December2005;IntergovernmentalPanelonClimateChange,1996(datafor2000).IndustrialprocessesENERGYWorldgreenhousegasemissionsbysector18.2%13.5%3.6%3.4%13.5%24.6%10.4%3.9%9%6%5.1%1.5%0.9%2%1.6%1.4%1,9%1,4%6.3%18.3%-1.5%-0.5%2.5%-0.6%3,8%5,0%4.8%1%1%1.4%1%9.9%1.6%2.3%3.5%5.4%9,9%3.2%18ter60–87Gtofatmosphericcarbonby2050,equivalenttosome12–15%ofprojectedCO2emissionsfromfossilfuelburningforthatperiod(Trumperetal.,2009).Itisbecomingbetterunderstoodthattherearecriticalthresholdsofanthropogenicclimatechange,beyondwhichdangerousthresholdswillbepassed(IPCC,2007a).Forexample,tokeepaveragetemperaturerisestolessthan2°C,globalemissionshavetobereducedbyupto85%from2000levelsby2050andtopeaknolaterthan2015,accordingtotheIPCC(Trumperetal.,2009).Butwhilethelossofgreencarbonecosystemshaveat-tractedmuchinterest,forexamplebycombatingtheEastAsiaSouthAmericaWesternAfricaSouthernAsiaSouth-EastAsiaEastAfricaMiddleEastNorthernAfricaEastEuropeCentralAmericaOceaniaJapanCanadaFormerUSSRUSASouthernAfricaBlackCarbonemissionsTeragramsperyear(2000)157080038020012042%18%14%10%10%6%OpenbiomassResidential-coalandothersTransport-nonroadTransport-roadIndustryandpowergenerationResidential-biofuelBlackCarbonemissionsSources:Bondetal.,2000.SharebysectorandgeographicdistributionFigure4:Combustionsourcesofblackcarbon.(Source:DennisClare,StateoftheWorld2009,www.worldwatch.org).19lossoftropicalrainforests,thefactthatnear55%ofallgreencarboniscapturedbylivingorganismsnotonland,butinoceans,hasbeenwidelyignored,possiblyourgreat-estdeficitinmitigatingclimatechange.Thecarboncap-turedbymarineorganismsishereincalled“bluecarbon”.BLUECARBONBluecarbonisthecarboncapturedbytheworld’soceansandrepresentsmorethan55%ofthegreencarbon.Thecarboncapturedbylivingorganismsinoceansisstoredintheformofsedimentsfrommangroves,saltmarshesandseagrasses.Itdoesnotremainstoredfordecadesorcentu-ries(likeforexamplerainforests),butratherformillennia.Inthisreport,theprospectsandopportunitiesofbindingcarboninoceansisexplored.Source:UNEP-WCMC,2009.GreenCarbonTonnesofCstoredperhectareTropical,Subtropical,Savannas,ShrublandsTropical,SubtropicalForestsDesertsandDryShrublandTemperateGrasslands,SavannasShrublandsTemperateForestBorealForestTundra547.8285.3178.0183.7314.9384.2155.450130325GigatonnesofCstoredinterrestrialbiomesFigure5:45%ofgreencarbonstoredinnaturalterrestrialecosystemsandtheremaining55%iscapturedbylivingor-ganismsinoceansbyplanktonandocean’sbluecarbonsinks.202122That’shere.That’shome.That’sus.Oniteveryoneyoulove,everyoneyouknow,everyoneyoueverheardof,everyhumanbeingwhoeverwas,livedouttheirlives.Theaggregateofourjoyandsuffering,thousandsofconfidentreligions,ideologies,andeconomicdoctrines,everyhunterandforager,everyheroandcoward,everycreatoranddestroyerofcivilization,everykingandpeasant,everyyoungcoupleinlove,everymotherandfather,hopefulchild,inventorandexplorer,everyteacherofmorals,everycorruptpolitician,every‘superstar’,every‘supremeleader,’everysaintandsinnerinthehistoryofourspecieslivedthere–onamoteofdustsuspendedinasunbeam.Lookagainatthatdot.CarlSagan1997.ImagefromthesolarsystemtakenbytheVoyager1spacecraft(NASA/JPL).23Theexistenceofthevastoceanisthemaindefiningcharacteristicofourplanet,mak­ingearthuniqueinthesolarsystemandtheonlyBluePlanet.Althoughwaterisnotuncommonintheuniverse,oceansareprobablyextremelyrare.Otherplanetsintheso­larsystemhaveevidenceofice,ancientwaterbasinsandvalleys,orevensubsurfaceliquidwater,butplanetearthistheonlyonewhichhasliquidsurfacewater;probablyduetoourprivilegedpositioninrespecttothesun:notcloseenoughtoevaporateandescape,norfarenoughtofreeze.Waterisalsolinkedtotheoriginoflife,inwhichearlyorganicmoleculesrestedprotectedfromtemperatureswingsandfromthesun’sdestructiveultravioletradiation,andwheretheycouldmovefreelytocombineandevolve.Thissuccessfulcombinationofwaterandlifechangedthecompositionoftheatmospherebyreleasingoxygenandextrawatervapour,andshapedourlandscape,throughero­sion,weatheringandsedimentation,inacontinuousinterchangeofwaterbetweentheocean,thelandandtheatmosphere.BLUEPLANET:OCEANSANDCLIMATEHowinappropriatetocallthisplanetearthwhenitisquiteclearlyOcean.ArthurC.ClarkeWatermovesinacontinuouscyclethatbeginsandendsintheocean.Thishydrologiccycleispoweredbysolarradiation,whichprovidesenergyforevaporation.Thenprecipitation,transpirationfromplants,runoffintostreamsandinfiltrationtogroundwaterreservoirscompletethecycle,whichwillstartoveragainwhenmostoftheinitialevaporatedwaterreachestheocean.Althoughduringthecycle,watercanbepresentindifferentstatesasice,liquidorvapor,thetotalwatercontentoftheoceanhasremainedfairlyconstantsinceitsformation,withanaverageresidencetimeofapproximately3,000years.Atthemoment,97.25%ofthewaterinplanetearthisintheformofliquidsaltywaterintheoceans,withonly2.05%formingicecoversandglaciers,0.68%groundwater,0.01%riversandlakes,and0.001%intheatmosphere(CampyandMaCaire,2003).Oceanshavebeeninfluencingtheclimateandtheecologyoftheplanetsincetheverybeginningoflifeonearth.Overtime,boththephysicaloceansandlivingorganismshavecontrib-utedtothecyclingofcarbon.Planktoninmarineecosystemsproducesmoreorganicmaterialthanisneededtomaintainthefoodchain.Theexcesscarbonslowlyaccumulatesontheseabedduringgeologicaltime(biologicalpump)(Longhurst,1991;SiegenthalerandSarmiento,1993;RavenandFalkowski,1999).Withthatprocess,sedimentandfossilizedcarbonateplanktonhavechangedtheshapeofourcoasts.24PHYSICALPUMPTransportofCO2byVerticalMixingandDeepWaterMassesPrimaryProductionOrganicCarbonOxygenRespirationEgestionFoodWebDecompositionNutrients(Nitrate)ParticulateCarbon(OrganicandInorganic)NutrientsCO2CO2CO2CO2CO2CO2Nutrients(Ammonia)CO2CO2CO2CO2CO2BacteriaOxidationBacteriaRemineralizationCarbonDepositionCarbonBurialSOLUBILITYPUMPTransportofCO2throughtheair-seainterfacePhytoplanktonHighLatitudesLowLatitudesVerticalMixingLocalActionShort-timeScaleLong-timeScaleGlobalActionDeepWaterMassesFormationAIR-SEAINTERFACECO2EXCHANGESATMOSPHERICCIRCULATIONPATTERNSSinkingBIOLOGICALPUMPVerticalgravitationalsettlingsofbiogenicdebrisNutrients(Nitrate)Sources:R.Chester,2003;H.Elderfield,2006;R.A.Houghton,2007;T.J.Luekeretal,2000;J.A.RavenandP.G.Falkowski,1999.25Figure7:Carbonfluxesintheoceans.(Source:adaptedfromTakahashietal.,2009).Oceansareabsorbingbothheatandcarbonfromtheatmosphere,thereforealleviatingtheimpactsofglobalwarmingintheenviron-ment.Coveringmorethantwo-thirdsoftheearth’ssurface,theoceansstorethesun’senergythatreachesearth’ssurfaceintheformofheat,redistributeit,fromthecoasttothemid-ocean,shal-lowtodeepwaters,polartotropical,andthenslowlyreleaseitbacktotheatmosphere.Thesestorageandcirculationprocessespreventabruptchangesintemperature,makingcoastalweathermildandsomehighlatitudeareasoftheglobehabitable.Howeverthishugeheatstoragecapacitycanhaveundesirableconsequenceswiththeadventofclimatechange.Withglobalwarming,theoceanisab-sorbingalargeportionoftheexcessheatpresentintheatmosphere(almost90%),resultinginameasurableincreaseofsurfacewatertemperatures(anaverageofapproximately0.64oCoverthelast50years)(Levitusetal.,2000;IPCC,2007b).Aswaterwarms,itex-Figure6:Carboncyclingintheworld’soceans.Theflowofcarbondioxideacrosstheair-seainterfaceisafunctionofCO2solubilityinseawater(SolubilityPump).TheamountofCO2dissolvedinseawaterismainlyinfluencedbyphysico-chemicalconditions(seawatertemperature,salinity,totalalkalinity)andbiologicalprocesses,e.g.primaryproduction.ThesolubilitypumpandthebiologicalpumpenhancetheuptakeofCO2bythesurfaceoceaninfluencingitsval-uesfordissolvedCO2andtransferringcarbontodeepwaters.Allthesemechanismsarestronglyconnected,subtlybalancedandinfluentialtotheocean’scapacitytosinkcarbon.TheneteffectofthebiologicalpumpinitselfistokeeptheatmosphereconcentrationofCO2around30%ofwhatitwouldbeinitsabsence(SiegenthalerandSarmiento,1993).MolofcarbonpersquaremetreOceanscarbonfluxes-10.5-0.51Source:MarineInstitute,Ireland,2009.NetcarbonreleaseNetcarbonuptake263134PracticalsalinityunitDeepwaterformationSurfacecurrentDeepcurrentDeepwaterformationDeepwaterformationPacificOceanPacificOceanAtlanticOceanIndianOcean3639(1psu=1gramofsaltperkilogramofwater)ThermohalinecirculationSource:NASA,2009.Figure8:Thermohalinecirculationisa3-dimensionalflowinvolvingsurfaceanddeepoceanwaters,whichisdrivenbydifferencesinwatertemperatureandsalinity.(Imagesource:NOAA/NCDC).pandscausingtheoceansurfacetorise(UNEP,2008b).Overtime,thisheatwilldescendtogreateroceandepths,increasingexpansionandtriggeringfurtherchangesinsealevel.MeltingofseaiceintheArctic,inlandglaciersandcontinen-talicesheetsofGreenlandandAntarcticaischangingthesa-linityofseawaterandinsomecasesalsocontributingtosealevelrise(UNEP,2008b).So,meltingandwarmingwillhavefurtherconsequencesonoceancirculation,asoceancurrentsaredrivenbytheinteractionsbetweenwatermassesthroughabalancewithtemperatureandsalinity,whichcontrolstheden-sity.Changesinoceaniccurrentscouldexposelocalclimatestoabruptchangesintemperature.Higherwatertemperaturesalsoleadtoincreasedevaporation,makingmoreenergyavail-ablefortheatmosphere.Thishasdirectconsequencesonextremeweatherevents,aswarmingseatemperaturesboostthedestructiveenergyofhurricanes,typhoons,etc.Tropicalsea-surfacetemperatureshavewarmedbyonlyhalfadegreeCelsius,whilea40%increaseintheenergyofhurricaneshasbeenobserved(SaundersandLea,2008).Warmer,lowsalinitysurfacewaterstogetherwiththeannualsea-sonalheatingareextendingandstrengtheningtheseasonallay-ersinthewater-column(stratification),limitingtheverticalmove-mentofwatermasses.Thisphenomenontogetherwithchangesinwindregimeshasimplicationsforsomeofthemostproduc-tivepartsofearth’soceans(LeQuéréetal.,2007),whereupwell-ingofdeepwatersandnutrientsenhancesprimaryproduction,supportingmassivelyabundantsurfaceecosystems.Ifreductionofupwellingoccurstoanydegree,marineecosystems,fisheries27andcommunitieswillbenegativelyaffected.Itisimportanttohighlightthatenhancedstratificationisalreadyafactintemper-ateseasatmid-latitudes,wherestratificationisdiminishingthetotalannualprimaryproductionasaresultofthereductioninthesupplyofnutrientstothesurfacelayers(Cushing,1989;ValdésandMoral,1998;Valdésetal.,2007).Warmingtemperaturesarealsochangingthegeographicalrangesofmarinespecies.Chang-esindepthrangeareoccurring,asspeciesshiftdowninthewatercolumntoescapefromwarmingsurfacewaters.Thereisalsoevidencethatthedistributionofzooplankton,fishandothermarinefaunahasshiftedhundredsofkilometerstowardshigherlatitudes,especiallyintheNorthAtlantic,theArcticOcean,andtheSouthwestPacificOcean(Cheungetal.,2009)AnotherimportantroleplayedbytheoceanisthestorageandexchangeofCO2withtheatmosphere,anditsdiffusiontowarddeeperlayers(solubilitypump)(Factbox2)(SiegenthalerandSarmiento,1993).Theoceanhasabsorbedapproximatelyone-thirdofthetotalanthropogenicCO2emissionssincethebegin-ningoftheindustrialera(SabineandFeely,2007).Insodoing,theoceanactedasabufferforearth’sclimate,asthisabsorptionofCO2mitigatestheeffectofglobalwarmingbyreducingitsconcentrationintheatmosphere.However,thiscontinualintakeofCO2andheatischangingtheoceaninwaysthatwillhavepotentiallydangerousconsequencesformarineecologyandbio-diversity.DissolvedCO2inseawaterlowerstheoceans’pHlevel,causingacidification,andchangingthebiogeochemicalcar-bonatebalance(GattusoandBuddemeier,2000;Pörtneretal.,2004).LevelsofpHhavedeclinedatanunprecedentedrateinsurfaceseawateroverthelast25yearsandwillundergoafurthersubstantialreductionbytheendofthiscenturyasanthropogenicsourcesofCO2continuetoincrease(Feelyetal.,2004).AstheoceancontinuestoabsorbfurtherheatandCO2,itsabilitytobufferchangestotheatmospheredecreases,sothatatmosphereandterrestrialecosystemswillfacethefullconsequencesofcli-matechange.Athighlatitudes,densewaterssink,transferringcarbontothedeepocean.WarmingoftheoceansurfaceinhibitsthissinkingprocessandthereforereducestheefficiencyofCO2transportandstorage.Furthermore,aswaterwarmsup,thesolu-bilityofCO2declines,thereforelessgascanbestoredintheseawater.Withacidification,warming,reducedcirculationandmix-ing,therehasbeenasignificantchangeinplanktonproductivityintheocean,reducingtheportionofthecarbonbudgetthatwouldbecarrieddowntothedeepseafloorandstoredinsediments.So,theoceansystemisbeingthreatenedbytheanthropogenicactivitieswhicharecausingglobalwarmingandoceanacidifica-tion.Aswaterswarmupandthechemicalcompositionoftheoceanchanges,thefragileequilibriumthatsustainsmarinebio-diversityisbeingdisturbedwithseriousconsequencesforthemarineecologyandforearth’sclimate.ThereisalreadysomeclearevidencethattheglobalwarmingtrendandincreasingemissionsofCO2andothergreenhousegasesareaffectingen-vironmentalconditionsandbiotaintheoceansonaglobalscale.However,weneitherfullyappreciatenordoweunderstandhowsignificanttheseeffectswillbeinthenearandmoredistantfu-ture.Furthermore,wedonotunderstandthemechanismsandprocessesthatlinktheresponsesofindividualsofagivenspe-cieswithshiftsinthefunctioningofmarineecosystems(Valdésetal.,2009).Marinescientistsneedurgentlytoaddressclimatechangeissues,particularlytoaidourunderstandingofclimatechangeeffectsonecosystemstructure,function,biodiversity,andhowhumanandnaturalsystemsadapttothesechanges.Thesolubilitypump:CO2issolubleinwater.Throughagas-exchangeprocessCO2istransferredfromtheairtotheocean,whereitformsofdissolvedinorganiccarbon(DIC).Thisisacontinuousprocess,asseawaterisunder-saturatedwithCO2comparedtotheatmosphere.TheCO2issubsequentlydistrib-utedbymixingandoceancurrents.Theprocessismoreeffi-cientathigherlatitudesastheuptakeofCO2asDICincreasesatlowertemperaturessincethesolubilityofCO2ishigherincoldwater.Bythisprocess,largequantitiesofCO2areremovedfromtheatmosphereandstoredwheretheycannotcontributeimmediatelytothegreenhouseeffect.Thebiologicalpump:CO2isusedbyphytoplanktontogrow.Theexcessofprimaryproductionsinksfromtheoceansur-facetothedeepsea.Intheverylongterm,partofthiscarbonisstoredinsedimentsandrocksandtrappedforperiodsofdecadestocenturies.InordertopredictfutureCO2concentra-tionsintheatmosphere,itisnecessarytounderstandthewaythatthebiologicalpumpvariesbothgeographicallyandtem-porally.Changesintemperature,acidification,nutrientavail-ability,circulation,andmixingallhavethepotentialtochangeplanktonproductivityandareexpectedtoreducethetrade-offofCO2towardstheseabed.Factbox2.Theocean–agiantcarbonpump28Freelivingmarinemicroorganisms(plankton,bacteriaandvi-ruses)arehardlyvisibletothehumaneye,butaccountforupto90%oflivingbiomassinthesea(Soginetal.,2006;Suttle,2007).Thesemicroscopicfactoriesareresponsiblefor>95%ofprimaryproductioninoceans,producingandrespiringamajorpartofthereducedcarbonororganicmatter(Pomeroyetal.,2007).PlanktonMorethan36.5GtofCO2iscapturedeachyearbyplanktonicalgaethroughphotosynthesisintheoceans(Gonzalez,etal.(2008).Zooplanktondynamicsareamajorcontrollingfactorinthesedimentationofparticulatecarboninopenoceans(BishopandWood,2009).OfthecapturedCO2,andanestimated0.5GtCyr–1isstoredattheseabed(Seiteretal.,2005).Marinevirusesandbacteria–significantinthecarbonbudgetMarinevirusesrequireotherorganiclifetoexist,butinthem-selveshaveabiomassequivalentto75millionbluewhales(11.25Gt).Theestimated1x1030virusesintheocean,ifstretchedendtoend,wouldspanfartherthanthenearest60galaxies(Sut-tle,2007).Althoughthestoryofmarinevirusesisstillemerging,itisbecomingincreasinglyclearthatweneedtoincorporatevi-rusesandvirus-mediatedprocessesintoourunderstandingofoceanbiologyandbiogeochemistry(Suttle,2007).Interactionsbetweenvirusesandtheirhostsimpactseveralimpor-tantbiologicalprocessesintheworld’soceansincludingbiogeo-chemicalcycling.Theycancontrolcarboncyclingduetocelllysisandmicrobialdiversity(byselectingforvarioushosts)(Wiggington,2008).Everysecond,approximately1x1023viralinfectionsoccurintheoceanandcauseinfectionof20–40%surfacewaterprokaryoteseverydayresultinginthereleaseof108–109tonnesofcarbonperdayfromthebiologicalpoolwithintheoceans(Suttle,2007).Itisthoughtthatupto25%ofalllivingcarbonintheoceansismadeavailablethroughtheactionofviruses(HoyleandRobinson,2003).Thereisstillacriticalquestionastowhetherviruseshinderorstimulatebiologicalproduction(Gobleretal.,1997).Thereisanongoingdebatewhetherviruses(1)shortcircuitthebiologicalpumpbyreleasingelementsbacktothedissolvedphase(Poor-vinetal.,2004),(2)primethebiologicalpumpbyacceleratinghostexportfromtheeuphoticzone(LawrenceandSuttle,2004)or(3)driveparticleaggregationandtransferofcarbonintothedeepseathroughthereleaseofstickycolloidalcellularcompo-nentsduringvirallysis(Marietal.,2005).BacteriaOceanbacteriaarecapableoftakingupCO2withthehelpofsunlightandauniquelight-capturingpigment,proteorhodopsin,whichwasfirstdiscoveredin2000(Bejaetal.,2001).Proteorho-dopsincanbefoundinnearlyhalfoftheseabacteria.KnowledgeofmarinebacteriamaycometobeofmajorimportancetoourunderstandingofwhattheclimateimpactofrisingCO2emis-sionsmeansfortheoceans.LifedeepbelowtheseabedLifehasbeenshowntoexistinthedeepbiosphere,even800mbelowtheseafloor.Itisestimatedthat90Gtofmicrobialorgan-isms(intermsofcarbonmass)arelivinginthesedimentsandrocksoftheseabed,withbacteriadominatingthetop10cm,butmorethan87%madeupbyagroupofsinglecellmicroorganismsknownasArchaea.Itisstillnotclearwhattheirecologicalfunc-tionsare,orevenhowtheysurviveinsuchalowfluxenvironment,livingonpreviouslydigestedfossilremains(Lippetal.,2008).Factbox3.Theroleofoceanvirusesandbacteriainthecarboncycle29SEVENDETRIMENTALWAYSINWHICHTHEOCEANSTHEMSELVESWILLBEAFFECTEDBYCLIMATECHANGEMELTINGOFARCTICSEAICEArcticsea-icereductionshavesignificantimpactsonclimate,wildlifeandcommunities.TheopeningofopenwateracrosstheArcticoceanwillhaveunknownconsequencesintermsofchangesinwatercirculationandredistributionofspeciesfromtheAtlanticandPacificoceans.Asseaicecoveragedeclines,albe-dodiminishesandmoreradiationisabsorbedbytheseawater,inafeed-backprocessthatenhanceswarmingandmeltingseaice.Theecologyoftheplanetiscloselylinkedtodifferentoceanprocesses,mostofwhicharedirectlyaffectedbyclimatechange.Figure9:Lossoftheicesheet.1SeaiceanomalyinNorthernHemisphereMillionsquarekilometres,from1978-2000averageSource:NOAA,2009.200020012003200520072009201020022004200620080.0-0.5-1.0-1.5-2.0-2.50.530OCEANCIRCULATIONANDTHERMALEXPANSIONMeltingandwarmingwillhaveconsequencesonoceancir-culation,asoceancurrentsaredrivenbytheinteractionsbetweenwatermassesthoughbalanceintemperatureandsalinity,inotherwords,theirdensity.AdditionallymeltingofinlandglaciersandcontinentalicesheetsonGreenlandandAntarctica,andthethermalexpansionofoceanwatersarecausingsealevelrise.Source:IPCC,2007.Sealevelanomalies(Metres)00.050.100.150.200.25andmore-0.05-0.10-0.15-0.20-0.25INCREASEDFREQUENCYANDSEVERITYOFSTORMEVENTSHigherwatertemperaturesleadtoincreasedevaporation,makingmoreenergyavailablefortheatmosphere,whichbooststhedestructiveforceofextremeweathereventslikehurricanes,typhoonsetc.32Figure10.Sealevelanomalies(seetext).31Sea-levelriseMetres1.000.750.500.25010001001010.1noadditionaleffortsundetakenstrongeffortstoprotectcoastalpopulationsagainstfloodsSource:H.Ahlenius,GEOIceandSnow,2007,basedonNicholls,R.J.andLowe,J.A.,2006.moreprotectioneffortsthantodayNote:TheuppermarginofeachbandshowstheamountofpeopleaffectedintheA2scenarioaccordingtowhichglobalpopulationwillreach14thousandmillionby2080withthelowestGDPofallIPCCscenarios.Thereforelittlecapacityexiststoadapt,andmorepeoplewillbeaffectedbyfloods.ThelowerendofeachcurveshowstheimpactfortheA1/B1scenarioassumingthehighestpercaptiaincomeandworldpopulationat8thousandmillion,allowingforhigherinvestmentsintheprotectionofthepopulation.Populationfloodedincoastalareasin2080Millionpeopleperyear(logarithmicscale)Figure12.Projectedpopulationfloodedincoastalareasby2080(seetext).NumberofdisastersperyearSource:CREDAnnualDisasterStatisticalReview2006,2007.45040035030025020015010050020015010050019001980198019851990199520002000192019401960201020052010250CyclonesFloodsEarthquakesEarthquakesAlldisastersAlldisastersinclude:drought,earthquake,extremetemperatures,famine,flood,insectinfestation,slides,volcaniceruption,waveandsurge,wildfires,windstorm.Muchoftheincreaseinthenumberofhazardouseventsreportedisprobablyduetosignificantimprovementsininformationaccessandalsotopopulationgrowth,butthenumberoffloodsandcyclonesreportedisstillrisingcomparedtoearthquakes.Isglobalwarmingaffectingthefrequencyofnaturalhazards?EarthquakesversusclimaticdisastersTrendsinnumberofreporteddisastersFigure11.Trendsinnumberofreporteddisasters(seetext).32WATER-COLUMNSTRATIFICATIONANDLOSSOFCOASTALPUMPSWarmingandmeltingisenhancingseasonalwater-columnstrati-ficationintheoceanonaglobalscale,mainlyintemperateseas.Somecoastal”flushing”mechanisms–so-calleddense-shelfwatercascading–mayalsobeweakenedwithclimatechange,resultinginslower“cleaning”ofpollutedcoastalwaters,morealgaebloomsanddeadzones,andlackoftransportoffoodparticlestoorganismslivinginthedeepseaandontheseafloor.Theresultingreductioninnutrientfluxwillcauseadeclineinprimaryproductionandpos-siblyinoceanproductivity.SHIFTSINDISTRIBUTIONOFSPECIESANDMIGRATORYROUTESThedistributionofplankton,fishandothermarinefaunahasshift-edhundredsofkilometerstowardhigherlatitudes,especiallyintheNorthAtlantic,theArcticOcean,andtheSouthwestPacificOcean.Additionallyoceanwarminghasnoticeableeffectsonthemigratoryroutesofmanyspecies.45OCEANACIDIFICATIONTheoceanisabsorbingexcessCO2fromtheatmo-spherewhichiscausingchangesinthebiogeochemi-calcarbonatebalanceoftheocean,andthussignifi-cantacidificationofoceanwaters.Theoceanisthussomehowalleviatingtheimpactsofglobalwarminginthebiosphere.Withclimatechangeandoceanacid-ificationalargereductionintheabilityoftheoceantotakeupatmosphericCO2isexpected.Thereduc-tionofpHandcalciumcarbonatesaturationlevelsintheoceanswillaffectthousandsofspeciesfromthewiderangeofmarineorganismswhichneedcarbon-ateintheirdevelopmentandforformingshellsandskeletons.Thestructureofmarineecosystemsareex-pectedtobeseverelyimpactedbyacidificationwithpotentialextinctionsandlarge-scalereductioninbio-diversityandecosystemservices,primarilybecauseofthespeedatwhichthesewaterchemistrychangesareoccuring.61958-19811982-19992000-2002MeannumberofspeciesperCPRsample0.00.11958-19811982-19992000-2002MeannumberofspeciesperCPRsample0.00.1811982-19992000-2002MeannumberofspeciesperCPRsample0.00.11982-19992000-2002MeannumberofspeciesperCPRsample0.00.11958–19811982–19992000–2002Source:IPCC,2007.OceanicCO2concentrationOceanwateracidityGlobaloceanacidification8.1419851990199520002005198519901995200020058.128.108.088.06atm380360340320300pHFigure13.Planktonmigrationshift.Figure14.Ascarbonconcentrationsintheatmosphereincrease,sodoconcentrationsintheocean,withresultantacidificationasanaturalchemicalprocess.Source:basedonAhlenius,H.,2008;PersonalcommunicationwithChrisReid,SAHFOS,Novem-ber2007.3319942100SupersaturationUndersaturationAragonitesaturationSources:Donner,S.D.,etal.,2005;Orr,J.C.,2005.MapbyHugoAlhenius.Coralbleachingisaphenomenoncausedprimarilybyabove-averagewatertemperaturesandhighradiationfromthesun,thatstressthemicro-algae(“zooxanthellae”)livingsymbioticallyincoralsandgivingthemtheirspectacularcolours.Whenthesemicro-algaebecomestressed,thecoralexpelsthem,sothatthecoral’swhitecalcareousskeletonisvisiblethroughthetransparenttissue–hencetheterm‘bleaching’.Bleachedcoralsareveryweakandpronetodisease,algalovergrowthandmortalityifthestressishighorcontinuesoverlongertimeperiods.In1998,amassglobalbleachingeventcausedthemortalityofanestimated16%oftheworld’scoralreefs,andunfortunatelybecauseofrisingseatemperaturesmassbleachingeventsarepredictedtoincreaseinfrequencyandintensity.Lossofcoralreefsalsomeanslossofrevenueandfoodforcoastalcommunitieswhodependonthem.LOSSOFCORALREEFSANDASSOCIATEDMARINEBIODIVERSITY719942100SupersaturationUndersaturationAragonitesaturationSources:Donner,S.D.,etal.,2005;Orr,J.C.,2005.MapbyHugoAlhenius.Figure15.Oceanacidification–ascarbonconcentra-tionsincreaseintheatmosphere,sodoconcentrationsintheoceans,withresultantacidifica-tion.Source:Donner,S.D.,etal.,2005;Orr,J.C.,2005.3435BLUECARBON–THEROLEOFOCEANSASCARBONSINKSVegetatedcoastalhabitats–mangroveforests,salt-marshesandseagrassmeadows–havemuchincommonwithrainforests:theyarehotspotsforbiodiversity,theyprovideimportantandvaluableecosystemfunctions,includingalargecarbonsinkcapacity,andtheyareexperiencingasteepglobaldecline(Duarteetal.,2008,Duarte,2009).Indeed,theworldislosingitscoastalhabitatsfourtimesfasterthanitsrainforests(Duarteetal.,2008,Duarte,2009)andtherateoflossisaccelerating(Waycottetal.,2009).However,whereassocietyiswellinformedofthebenefitsandthreatsassociatedwithrainforests,thereisacomparativelackofawarenessonthestatusandbenefitsofvegetatedcoastalhabitats.Thisisperhapsbecauseofa“charisma”gap,wheretheseoftensubmerged,outofsightcoastalhabitats,arenotasappealingtothepublicastheirterrestrialcounterparts(Duarteetal.,2008).Yet,becauseoftheirsimilarfunctionsandthreats,coastalhabitatscanbeconsideredasbluecarbonsinks.BLUECARBONSINKSOnekeyfunctionofvegetatedcoastalhabitatsistheirroleascarbonsinks.Benefitingfromtheexcellentconditionsavail-abletosupportplantgrowth,vegetatedcoastalhabitatsrankamongstthemostproductivehabitatsintheworld,comparableinproductiontothemostproductiveagriculturalcrops(Table1,DuarteandChiscano,1999).Muchoftheirproductionisusedtosupportecosystemfunctions(DuarteandCebrián,1996).However,bluecarbonsinksarestronglyautotrophic,whichmeansthattheseecosystemsfixCO2asorganicmatterphoto-syntheticalyinexcessoftheCO2respiredbackbybiota(DuarteandCebrián,1996;Gattusoetal.,1998;Duarteetal.,2005a),thusremovingCO2fromtheatmosphere.Someofthisexcesscarbonisexportedandsubsidisesadjacentecosystems,includ-ingopenoceanandbeachecosystems(DuarteandCebrián,1996;Hecketal.,2008;Bouillonetal.,2008).Theremainingexcessproductionofmangroveforests,salt-marshesandsea-grassmeadowsisburiedinthesediments,whereitcanremainstoredovermillenarytimescales(Mateoetal.,1997),therebyrepresentingastrongnaturalcarbonsink.Thisismostevidentinthecaseofseagrassmeadows,whichaccumulateenoughmaterialsastosignificantlyraisetheseafloor,formingmatsthatcanexceed3metresindepth.Inadditiontoburyingafractionoftheirownproduction,bluecarbonsinksreduceflow,alterturbulenceandattenuatewaveaction(Kochetal.,2006),therebypromotingsedimentationandreducingsedimentresuspension(e.g.GaciaandDuarte,2001).Recentresearchhasshownthatthecanopiesofseagrassmeadowstrapparticlesentrainedintheflow,whichlosemo-mentumuponimpactingontheleaves,therebypromotingthesedimentationofsuspendedmaterialtotheseafloor(Hendriks36Source:UNEP-WCMC,2009;Valielaetal.,2001Mangroves0%5%10%15%20%25%30%Habitatlostsince1940sLossrateperyearinrecenttimes0%5%10%15%20%25%30%Habitatlostsince1940sHabitatlossrateperyearinrecenttimesSaltMarshesSource:UNEP-WCMC,2009;Duarteetal.,2008.370%5%10%15%20%25%30%Habitatlostsince1940sLossrateperyearinrecenttimesSeagrassSource:UNEP-WCMC,2009;Waycottetal.,2009.etal.,2007).Isotopicanalysesoftheorganiccarbonaccumu-latedinsedimentsofvegetatedcoastalhabitatshaveshownthatasignificantfractionderivesfromplankton(Gaciaetal.,2002).Onthecontinentalshelfandinestuaries,terrestrialsourcesofcarbonarealsosignificant(Bouillonetal.,2008),addingtothecarbonsinkcapacityofthesebluecarbonsinks.Aconsequenceofthecapacityofvegetatedcoastalhabitatstoaccumulatematerialsintheseaflooristhattheyactasefficientcarbonsinks,globallyresponsiblefortheburialof120–329TgCyr–1,whichaccountsforatleasthalfofthelowerestimateforglobalcarbonburialinmarinesediments(Table1).Bluecarbonsinksthereforeplayamajorroleintheoceaniccarboncycle(Duarteetal.,2005a).Thecarbonburialcapacityofma-rinevegetatedhabitatsisphenomenal,180timesgreaterthantheaverageburialrateintheopenocean.Carbonburialintheoceanrepresentsslightlyover10%oftheoce-aniccarbonsinkcapacity(upto25%usingmaximumestimates,Table1,seebelow),estimated,fromobservationsandinversemodels,tobeabout2,000TgCyear–1(SarmientoandGruber,2002).However,this2,000TgCyear–1isthecarbonannuallytransferredfromtheatmospheretotheoceans,whereitislargelystoredasdissolvedinorganiccarbon.Thelong-termresidenceofanthropogenicCO2intheoceansisuncertain,asthiscarbondoesnotpenetratedeepenoughtoremainintheoceanoverextendedtimescales.Indeed,halfoftheanthropogeniccarbonstoredinoceanwatersiscontainedwithinthetop400metres,whereitmayequilibratebacktotheatmospherewithinafewde-cades,andtheamountpresentinthedeepocean–whereitmayremainovermuchlongertimescales–isbelowthedetectionlimit(Sabineetal.,2004).Onlyaminuteamountofthecarbontakenupbytheoceansispreservedinthedeep-seasediments,whereitiseffectivelyburiedoverlongperiodsoftime,represent-ing6TgCyr–1,withacarbonburialperunitareaofseafloor180timeslowerthantherateforbluecarbonsinksediments(Table1).Inaddition,thereareconcernsthatthecapacityofthewatercolumnoftheoceanstoactasasinkforatmosphericcarbonwillweakeninthefuture,andthereisevidencethatitmayhavestartedtodoso(Doneyetal.,2009).Hence,onlycarbonseques-Figure16a–c:Distributionoftheworld’sbluecarbonsinks–seagrasses,mangroves,andsaltmarshcommunities(Source:UNEP-WCMC).38teredinmarinesediments,asinthecaseofbluecarbonsinks,canbesafelyconsideredtorepresentalong-termmarinecarbonstorage.Bluecarbonsinks,whichcoverlessthan0.2%ofthesea-floor,contributeabout50%(71%usingmaximumestimates,seeTable1)ofthetotalburialoforganiccarboninoceansedimentsandthereforerankamongstthemostintensecarbonsinksinthebiosphere(Duarteetal.,2005a).Yetcoastalvegetatedhabitatshavebeenneglectedfromaccountsoftheglobalcarboncycleandglobalinventoriesofnaturalcarbonsinks.Bluecarbonsinksarebuiltbyplantsandtrees(otherwiseknownasangiospermssuchasmangroves,salt-marshplantsandseagrasses)butthecoastaloceanalsocontainsvastareascoveredbyalgalbeds.Mostmacroalgalbeds(includingkelpforests)donotburycarbon,astheygrowonrockysubstrateswhereburialisimpossible.UNCERTAINTYANDUPPERESTIMATESOFCARBONSINKBYBLUECARBONSINKSThereisuncertaintyabouttheseglobalrates,duetouncertain-tiesintheirarealextentaswellasvariabilityincarbonburialratesamongindividualecosystems,althoughindependentestimatesforsomeecosystems,suchasmangroveforests,agreeremarkablywell(Bouillonetal.,2008).Forinstance,es-timatesoftheareacoveredbymangroves,probablythebestconstrainedamongstvegetatedcoastalhabitats,rangesfrom0.11to0.24millionsqkm(Bouillonetal.,2008).Estimatesoftheareacoveredbyseagrassmeadows,theleastconstraintestimate,rangefromadocumentedareaof0.12millionsqkm(GreenandShort,2003),toanupperestimateof0.6millionsqkm(DuarteandChiscano,1999)astheSouthEastAsianarchipelagos,suchasIndonesia,arelikelytoholdvast,un-chartedseagrassmeadows(Duarteetal.,2009).Indeed,thecoastalareawithsufficientsubmarineirradianceastosupportseagrassmeadowshasbeenestimatedat5.2millionsqkm(Gattusoetal.,2006).Hence,athoroughinventoryofbluecarbonsinksmaywellyieldacovertwiceaslargeasthemeanareaconsideredincurrent,conservativeglobalassessments(Table1).Individualbluecarbonsinkecosystemsalsovarygreatlyintheircapacitytoburycarbon,withthemaximumreportedratecorrespondingto17.2tCha–1yr–1inasaltmarsh(Table1).Themaximumcarbonburialratesforanyonehabi-tattypeare3to10timeshigherthantheglobalmeanvaluefortheseecosystems(Table1),providingevidenceofthevery39largecarbonsinkcapacityofsomespecificvegetatedcoastalhabitats.Indeed,themaximumreportedcarbonsinkcapacityofsalt-marsh,mangroveandsea-grassecosystems(Table1)exceedsbyover10,6and2foldthatofundisturbedAmazonianforest,estimatedat1.02tCha-1(Graceetal.,1993).Forinstance,carbonburialbysaltmarshes,whichcoverasmallareaoftheconterminousUSA,hasbeenestimatedtoaccountfor21%ofthetotalcarbonsinkofallUSAecosystems(Bridghametal.,2006).Hence,anupperestimateofthecarboncapturecapacityofbluecarbonsinkscanbederivedbycombiningmaximumestimatesoftheareacoveredgloballywithupperestimatesofthecarbonbur-iedperunitarea(Table1).Thesecalculationsyieldanupperestimateforthecarboncapturecapacityofbluecarbonsinksat329TgCyear–1,accountingfor71%oftheburialoforganiccarbonintheocean(Table1).ComponentAreaTonCha-1y-1TgCy-1OrganicCarbonburialMillionkm2VegetatedhabitatsMangrovesSaltMarshSeagrassTotalvegetatedhabitatsDepositionalareasEstuariesShelfTotaldepositionalareasTotalcoastalburial%vegetatedhabitatsDeepseaburialTotaloceanicburial%vegetatedhabitats0.17(0.3)0.4(0.8)0.33(0.6)0.9(1.7)1.826.6330.01.39,0.20–6.54(1.89)1.51,0.18–17.3(2.37)0.83,0.56–1.82(1.37)1.23,0.18–17.3(1.93)0.50.20.0001817–23.6(57)60.4–70(190)27.4–44(82)114–131(329)81.045.2126.2237.6(454)46.89(0.72)6.0243.62(460)45.73(0.71)Table1.Meanandmaximum(inbrackets)estimatesoftheareacoveredbybluecarbonsinksandtheannualorganiccarbonburialrates.Carbonburialratesarepresentedperhectare(mean,rangeand,theupperconfidencelimitofthemeanofindividualecosystemestimates,inbrackets)andglobally(asreportedrangesofmeanratesofglobalcarbonburialderivedusingdifferentmethodsand,inbrackets,anupperestimatederivedusingthemaximumareaandtheuppercon-fidencelimitofthemeanburialrate).Thedataisforvegetatedcoastalareasandtheirpercentagecontributiontocarbonburialinthecoastalandglobalocean(inbracketstheburialrateandpercentagecontributionofvegetatedhabitatscalcu-latedfromtheupperestimates).Totalburialratesoforganiccarboninestuarineandshelfsedimentsanddeep-seasedimentsareprovidedforcomparison.DataderivedfromreviewsbyCebriánandDuarte(1996),Duarteetal.(2005a),andBouillonetal.(2008).40Severalstudiessuggestthattheoceanshavetakenuparound2,000–2,200TgCyr–1overthepasttwodecades(Gurneyetal.2002,Plattneretal.2002,Sabineetal.2004,Benderetal.2005,Milleretal.2005,ManningandKeeling2006).Theup-takeincreasedslightlyfromaroundanestimated1800inthe1980s,to2,200TgCyr–1inthe1990sandthefirsthalfdecadeofthetwenty-firstcentury(McNeiletal.2003,Canadelletal.2007).However,onlyaportionofthiscarbonisactuallystoredpermanentlyintheoceans,asmuchisrecycledandreleasedbackwithinafewdecades.Coastalecosystemsarecurrentlystoringanamountofcarbonequivalenttoaround25%oftheestimatedannualincreaseofapproximately2,000TgCyr-1intheatmosphere.Currently,fossilfuelemissionsareestimatedat7,200TgCyr–1,whichresultsinapproximately2,000TgCyr-1increaseintheatmosphereperyear.Lossesofseagrasscommunities,man-groves,andsaltmarsheshaveacceleratedfromaround0.9%peryearinthefirstthreequartersofacenturytoupto7%peryearinthemorerecentdecades.Undercurrentscenarios,mostbluecarbonsinkswillbelostinthenexttwodecadesleadingtoalossofannualcarbonbindingcapacityequivalentto4–8%ofthetotalanthropogenicinput.Hence,totalemissionswouldthereforehavetobereducedbyanadditional4–8%by2030toretainthestatusquo,or10%by2050.Incomparison,thetotalgainestimatedfromtheUNREDDprogrammeiffullyimple-mented(includingslowingdeforestationandwideafforestationprogrammes),wouldby2050accordingtotheIPCCamounttoap-proximately12–15%oftherequiredemissionreductions.Preventingthelossoftheoceansbluecarbonsinkswouldmeanasignificantcontributiontoreducingclimatechange,evencomparedtoslowingdeforestationoftropicalrainforests.Afforestationprogrammesofmangrovescouldenhancethisevenfurther.Theupperestimateofstorageinoceansisapproximately450TgCyr–1–equivalentnear10%oftherequiredemissionreductions.Hence,“Blue”and“Green”carboncombinedcouldbindatleast25%oftheprojectedrequiredemissionreductions.Factbox4.Oceancarbonintheglobalcycle?Table2.TheGlobalcarbonbudgetTgCyr–1–around2,200TgCarecapturedperyearinoceans,butonlyaportionofitisstored,mainlyinsedimentsinoceansbluecarbonsinks,suchasman-groves,marshesandseagrasscommunities(Canadelletal.,2007;Houghton,2007).1980s(TgCyr–1)FossilfuelemissionsAtmosphericincreaseOceanicuptakeNetterrestrialfluxLand-usechangeResidualterrestrialflux5200±300–2900±100–1900±600–400±7001500±800–1900±11006400±300–3200±200–2200±700–100±8001600±800–2600±11007200±300–4200±100–2200±400–800±8001500±800–2300±11001990s(TgCyr–1)2000–2005(TgCyr–1)41Interesthasbeengrowingintheuseofgeo-engi-neeringtoprovideatechnicallyandpotentiallycommerciallyviablemitigatingsolutiontocombatincreasingatmosphericCO2concentrations(seeIPCC,2005foranoverview).Severalofthesepro-posalsintendtoenhancethefunctionoftheoceanasacarbonsink,ortostoreCO2insubseageologi-calformations.Someofthesesuggestionsmightsounddramaticandfarfetched,butiftheconceptsarescientificallysoundandtechnicallyfeasible,theyshouldnotbedisregarded.However,evaluatingthesenewinnovationsisinmostcasesnotasimplestory,astheyposesignificantecological,econom-ic,politicalandethicalchallenges(NatureNews,2009)givingcauseforconcern.Withtoomanyun-knownvariablesandcurrentmodelinglimitations,assessmentoftherisksandconsequencesoftheseproposalswillbeachallenge.Therearetwomainapproaches.Thefirstistore-duceenergyenteringtheearth’ssystembyblock-ingradiationsoitcannotbeabsorbedinthefirstinstance(e.g.sprayingaerosolstoincreasecloudcover,useofsolarshades,increasingreflectiveca-pacityofurbanareas);thesecondistoreducetheconcentrationofCO2intheatmospherebytrans-ferringitintolongtermstoragereservoirs,therebyfacilitatingtheescapeofenergyfromtheearth(LentonandVaughn,2009;IEA,2004).Theseap-proachesareatvaryingdegreesofdevelopment;whilesomehavebeenthroughin-situexperimen-tation,othersarestilljusttheoretical.Currentre-searchshowsthatmostoceangeo-engineeringconceptsarehighriskforundesirableside-effects(e.g.increaseinoceanacidification),havelimitedapplication,uncertainoutcomeandpotentiallynon-reversibleimpactsonthemarineenvironment.Thishighlightstheneedtoapplyaprecautionaryapproachwheninvestigatingoceangeo-engineer-inginterventions.Factbox5.Geo-engineeringproposalsformitigatingCO2DeepSea33026.61.80.30.40.2ShelfEstuariesSaltmarshesSeagrassesMangrovesBluecarbonsinkOrganiccarbonburialrateTeragramsperyear0.00021.806.517.5MarinehabitatareaMillionsquarekilometresMaximumMinimumAverageSource:CebriánandDuarte,1996;Duarteetal.,2005a;andBouillonetal.,2008.Figure17:Bluecarbonsinks.42ProposalConceptStatusofresearchOceanfertilizationAlteringoceanmixingIncreasingoceanalka-linityApproximately13smallscaleinsituexperimentshavebeenconductedsince1993,buthaveprovenincon-clusiveabouttheCO2sequestrationeffectivenessofoceanfertilization;Tomakeaviablecontributiontoreducingatmospher-icCO2concentrations,oceanfertilizationwouldhavetobecarriedoutoverlargeareas,andpotentiallywouldneedtobesustainedonamillennialtimescale(LentonandVaughan,2009);Internationalconcernhasbeenexpressed,interalia,aboutthehighecologicalrisks.Internationalbodiesandexpertshavecalledforrestrictionsandcaution(e.g.IMO,2007;CBD2008;Gilbertetal.,2008;Sei-belandWalsh2001);PartiestotheLondonConventionagreedthat,giventhepresentstateofknowledge,oceanfertilizationactivitiesotherthanlegitimatescientificresearchshouldnotbeallowed.Anassessmentframeworkforfuturescientificresearchandin-situexperimentsisunderdevelopment(IMO,2008).Neverreachedfieldtrialstage;Calculationsindicatesequestrationfluxthatwouldbeachievedistrivialonanymeaningfultimescale;andcostly(LentonandVaughan,2009).Thisisasyethighlytheoretical,butunderactivere-search,e.g.byCquestrate,whichisanopensourceprojecttoexploretheidea,encouragingevidencebaseddebateandinvestigation(Cquestrate,2009);ItispossiblethattheCO2emissionsgeneratedfrompreparingthecarbonatematerialwouldmatchtheCO2sequestered(LentonandVaughan,2009).Primaryproductioninsomeareasoftheoceanislim-itedbymacroormicronutrients(suchasiron,silica,phosphorusornitrogen).Byincreasingtheavailabilityofthesenutrients,primaryproductivitycouldbein-creasedresultinginanaccelerationofthenaturalrateofCO2uptakebytheoceansfrom2GtCyr–1(Huese-mann,2008)andincreaseCO2storageinthedeepsea.AnyCO2storedinthiswaywouldberemovedfromtheglobalcarboncycleforupto1,000years.Promotedbycommercialgroupsandenterprises(e.g.Climos)andwithpotentialfortradingcreditsonthevoluntarycarbonmarket.Useof200mlongoceanpipestoenhancethemixingandupwellingofnutrientrichwaters(e.g.LovelockandRapley,2007);Enhancedownwellingbyusingfloatingpumpstocoolwatersandformandthickenseaice(ZhouandFlynn,2005)Increasingthealkalinityoftheoceansby:Addingcarbonate,therebyincreasingthecapacityofthewatertoabsorbCO2(Kheshgi,1995).Harvey(2008)suggestedtheuseoffinelygroundlimestone,otherproposalsforeseetheuseofthermallydecom-posedlimestone(Cquestrate,2009);EnhancingthesolubilityofCO2intheoceansbyapro-cessequivalenttothenaturalsilicateweatheringreac-tion.HCliselectrochemicallyremovedfromtheoceanandneutralizedthroughreactionwithsilicaterocks.Table3.Anoverviewofthemainoceancarboncyclegeo-engineeringproposals,theconceptbehindtheseideasandcurrentstatusofinvestigation.••••••••••43ProposalConceptStatusofresearchGeologicalcarbonstor-ageDissolutioninjectionofCO2intothewatercolumnCO2injectionontotheseafloorTheincreaseinoceanalkalinityresultingfromtheremovalofHClcausesatmosphericCO2todissolveintotheoceanwhereitwillbestoredprimarilyasHCO3-.(Houseetal.,2007);Thesearetheonlymarinegeo-engineeringproposalsthatwouldremoveCO2fromtheatmospherewithoutcausinganincreaseofoceanacidification.InjectionofCO2intodeepgeologicalformationssuchassalineaquifersordepletedoilandgasreservoirsbe-lowtheseafloorCO2istransportedbyshiporpipelineoffshoreandtheninjectedintothewatercolumnatgreatdepth(>1000mordeeper)wheretheCO2dissolvesandremainsiso-latedfromtheatmosphereforcenturies.(UNESCO-IOC/SCOR,2007);CO2isplaceddirectlyontotheseaflooratdepthsgreat-erthan3000m,wheretheCO2wouldformlong-lasting‘lakes’withlowdissolutionrates.Inoperationsince1996.Measuresandguidance(e.g.toreducetheriskfromleakages)wereadoptedbyinternationalbodies(IMO/LondonConvention,OSPAR).Studieshavebeingconductedtoresearchandmodellongtermconsequencesandhowsecuresuchstoragewouldbe(e.g.Gilfillanetal.,2009,StatoilSleipnerProject)Bothconceptsbeensubjecttoyearsoftheoreticalresearch/modelingandsomesmallscalefieldex-periments,buthaveyetbeendeployedorfullytested(UNESCO-IOC/SCOR,2007).ResearchindicatesthattherewouldbeagradualreleaseofinjectedCO2backtotheatmosphereoveratimescaleofhundredsofyearstomillennia(dependingondepthandlocalsiteconditions);Thereisnoknownmechanismforpreventingcata-strophicacutereleaseofinjectedCO2(UNESCO-IOC/SCOR,2007),therearesignificantenvironmen-talrisksandimpactsassociatedwiththeseproposedmethodsofstorage(IPCC,2005;Sedlaceketal.,2009).InjectionofCO2intothewatercolumnorontheseabedaffectsmarineorganismsnearbyandoceanchemistry(e.g.byincreasingacidity).Inthelightofthepotentialforsevereenvironmentalim-pact,theplacementofcarbondioxidestreamsinthewatercolumnorontheseabedhasbeenprohibitedin2007viatheamendmentoftheLondonConven-tionProtocolandinalegallybindingdecisionagreedunderOSPAR(OSPAR,2007).••••4445Vegetatedmarinecoastalhabitats,bluecarbonsinks,rankamongstthemostthreat­enedmarineecosystems(Duarteetal.,2008;Duarte2009).Coastaleutrophication,reclamation,engineeringandurbanisationhaveleadtothelossofasubstantialfractionoftheearth’sbluecarbonsinkssincethe1940s(Duarteetal.,2008;Duarte2009)THEWORLD’SOCEANCARBONSINKSINRAPIDDECLINEArecentassessmentindicatesthataboutone-thirdoftheglob-alseagrassareahasbeenalreadylost,andthattheselossesareaccelerating,fromlessthan0.9%year–1inthe1970’stomorethan7%year–1since2000(Waycottetal.,2009).About25%oftheareaoriginallycoveredbysalt-marsheshasbeengloballylost(Bridghametal.,2006),withcurrentlossratesatabout1to2%year–1(Duarteetal.,2008).Valielaetal.(2001)estimatedthatatotalofabout35%oftheareaoncecoveredbymangroveshadbeenlostgloballysincethe1940s,withcurrentlossratesatabout1to3%year–1.Hence,aboutone-thirdoftheareacoveredbybluecarbonsinkshasbeenlostalreadyandtherestisseverelythreatened.Marinevegetatedhabitats,bluecarbonsinks,rankamongstthemostthreatenedhabitatsintheBiosphere,withgloballossrates2to15timesfasterthanthatoftropicalforests(0.5%year–1,Achardetal.,2002).Thelossofbluecarbonsinksrepresents,inadditiontotheimpactsonbiodiversityandcoastalprotectionin-volved,thelossofanaturalcarbonsink,erodingthecapacityofthebiospheretoremoveanthropogenicCO2emissions.TheSouthernOceansarerecognisedasanimportantcarbonsinkcurrentlytakingupapproximately15%ofanthropogenicCO2(CSIRO,2007).Modelspredictthatastheatmosphericconcentra-tionofCO2increases,soshouldtheocean’sabsorbtivecapacity.Thisseemstobehappeninginmostareas,butnotsointheSouth-ernOcean(CSIRO,2007;LeQuéréetal.,2007;LentonandMetzl,2009).Whilstscientistsagreeonthedata,thereissomedebateastowhythismaybe–possiblydecreasedozonewithincreasedGHGleadingtostrongerwindsandthereforegreatermixing,butdespitethecause,thistrendhaspotentiallyseriousimplicationsforamt-mosphericCO2concentrationsincomingyears.Factbox6.IstheabilityoftheSouthernOceanstobindcarbonalsoweakening?Figure18:DecliningabilityoftheSouthernocean’sabilitytoabsorbCO2.SouthernOceancarbonsinkchangeGigatonnesofcarbonperyearSource:NASA,2008.19701980199020000.0-0.5-1.01.0-1.51.5-2.00.5ExpectedObserved46--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------0510152025ShelfSeagrassSaltmarshesEstuariesMangrovesDeepseaMaximumburialrateAverageburialrateTeragramsofcarbonperhectareperyearBluecarbonsinkburialratestonsofcarbonperhectareperyearSources:CebrianandDuarte,1996;Duarteetal.,2005.47--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------020406080100EstuariesSaltmarshesShelfSeagrassesMangrovesDeepseaMaximumburialrateAverageburialrateTeragramsofcarbonperyearSources:CebrianandDuarte,1996;Duarteetal.,2005.TotalannualbluecarbonsinkburialratesFigure19a–b:Thecapacityofocean’sbluecarbonsinks.48495051Aquaticecosystemsprovideservicesthatcontributetohumanwelfare,bothdirectlyandindirectly.Thesemayberecognizedbytheirdirectbenefits,suchassourcesofemploy­ment,incomeandfoodsecurity,tourism,scientificresearchandmineralextraction;bytheirindirectbenefits,suchasclimateregulationandtransportation;andbytheirintrin­sicvalue,suchastheconservationofbiodiversityandsocialidentitiesandtheircontinu­ationtosupportfuturegenerations(KayandAlder,2005).OCEANS’BLUECARBONSINKSANDHUMANWELLBEINGItisestimated,thattheaverageannualvalueofservicesfromtheworld’scoastalecosystemsexceedsUS$25,000billionperyear(Martínezetal.,2007).Hence,thecoastalzoneisofmajoreconomicimportancetodaymuchasithasbeenthroughouthumanhistory.Climatechangeisprojectedtoimpactacrossecosystems,societ-iesandeconomies,increasingpressuresonalllivelihoodsandfoodsupplies,includingthoseinthefisheriesandaquaculturesector.Maintenanceoffoodqualitywillhaveamorepivotalroleasresourcescomeundergreaterpressure,andavailabilityandaccessto,forexample,fishsupplieswillbecomeanincreasinglycriticaldevelopmentissue(Cochraneetal.,2009;FAO,2008).IMPACTSTOFOODSECURITYTHROUGHTHEOCEANSANDCOASTSTheclimatechangeinducedalterationswhichtheoceanswillexperience,includingincreasingtemperatures,acidificationandchangesincurrentswillultimatelyaffectfisheriesandaquacul-ture.Fishdistributionsarepredictedtochange,andalreadyweFishcatchTonnespersquarekilometre5andmore3to51to30.5to10.25to0.50.2to0.25Sources:basedonAlhenius,H.,2008;FAO,2008.Figure20:Theworldsmostproduc-tivefishinggroundsareconfinedtomajorhotspotsinaround7.5%oftheoceansurface,whereoverhalfofthefisharecaught.FishcatchTonnespersquarekilometre5andmore3to51to30.5to10.25to0.50.2to0.25Sources:basedonAlhenius,H.,2008;FAO,2008.FishcatchTonnespersquarekilometre5andmore3to51to30.5to10.25to0.50.2to0.25Source:basedonAlhenius,H.,2008;SeaAroundUsproject,personalcommunicationOctober2007(UniversityofBritishColumbia).52--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------05000100001500091000SeagrassSaltmarshesMangrovesDeepseaCoastalplanktonCoralreefRangesofdifferentvaluesfoundinliteratureCurrentrangesoftotalvaluationestimatesofbluecarbonsinksperhectareEcosystemservicevalueperhectareUSdollarsSources:Martinezetal.2007;GunawardeanandRowan,2005;Spurgeon,2004;Costanza,1997.Figure21:Althoughcoastalecosystemsarealreadyamongthemostvaluableontheplanet,thecurrentestimatesoftheeconomicvalueforsomeoftheoceansbluecarbonsinksaresurprisinglylow.Howshouldhumanperceptionoftheseimportantecosystemschangeaswelearnofthevastbenefitsofmain-taininghealthycoastsandoceans?53Factbox7.Healthyaquaticecosystemscon-tributetofoodsecurityandlivelihoodsFisheriesandaquaculturecontributesignificantlytofoodsecu-rityandlivelihoods,butdependonhealthyaquaticecosystems.Thesecontributionsareoftenunrecognizedandundervalued.Over500millionpeopleindevelopingcountriesdepend,di-rectlyorindirectly,onfisheriesandaquaculturefortheirliveli-hoods.Fish(includingshellfish)providesessentialnutritionfor3billionpeopleandatleast50%ofanimalproteinandessentialmineralsto400millionpeopleinthepoorestcountries.Aquacultureistheworld’sfastestgrowingfoodproductionsystem,growingat7%annually–buttheproductionofex-ternallyfedaquaculture(48%oftotalaquacultureproduc-tion)islargelydependentuponmarinefisheriesforfeed.Fishproductsareamongthemostwidelytradedfoods,withmorethan37%byvolumeofworldproductiontradedinter-nationally.Naturalbarrierssuchassanddunes,mangroveforestsandcoralreefsdampentheimpactsofarangeofcoastalhaz-ards,includingstorm/cyclonesurgesandtsunamiwaves,helpingtoprotectcoastlinesfromtheirfullimpact.Source:PaCFA,2009•••••areseeingshiftsinspeciesdistributionsintheNorthSeawithnearlytwothirdsofthecommerciallyimportantspeciesshift-ingnorthwardinmeanlatitudeordeeperindepthorbothsince1970(Perryetal.,2005;Dulveyetal.,2008).Recentprojectionsofchangesinthedistributionrangesofmorethan1,000com-merciallyimportantfishspecies,basedonclimatechangesce-nariosto2050predictnumerousspeciesextinctionsinsub-polarregions,thetropicsandsemi-enclosedseas(Cheungetal.,2009).Climatechangewillalsoimpactthelevelsofinvasivemarineor-ganisms,whichoftendamagecommercialfishstocks.StudiespredictspeciesinvasionwillbeprofoundintheArcticandSouth-ernOceans(Cheungetal.,2009).Indeed,togetherthesechangescouldresultinasignificantturnoverofspeciesofmorethan60%ofpresentbiodiversity.Thishasthepotentialtodisruptarangeofmarineecosystemservicesincludingfoodprovisioning.Climatechangewillimpactacrossallthefourdimensions(availability,stability,accessandutilization)offoodsecurity.Availabilityofaquaticproductswillvarythroughchangesineco-systems,production,speciesdistributionandhabitats.Changeswilloccuratregionalandlocallevelsinfreshwaterandmarinesystemsduetoecosystemshiftsandchangingaquacultureop-tions,whichdependonavailabilityofkeyinputs.Production54ChinaTaiwanNorthKoreaSouthKoreaJapanRyokyoIss.DiaoyutaiIss.ChinaTaiwanNorthKoreaSouthKoreaJapanRyokyoIss.DiaoyutaiIss.020050090014001600ormoreLarimitchthyspolyactiscatchinearly2000s...Tonnes...andpredictedcatchshiftSources:Cheung,W.,C.,etal.,2008.Figure22:(a)Current(early2000s)and(b)cli-mate-shifteddistributionsofthesmallyellowcroakerLarimichthyspolyactis(Sciaenidae).Theclimate-shifteddistributionwaspredictedbyadynamicbioclimateenvelopemodeldescribedbyCheungetal.(2008),underahypotheticalincreaseinaverageglobaloceantemperatureof2.5°C.BoundariesofExclusiveEconomicZonesaredelineatedbythedashedlines.55fromaquaticresources,whetherthroughfisheriesoraquacul-ture,maybeimpactedbytheadaptivecapacityofmanagementmeasurescontrollingtemporalandspatialaccess.Stabilityofsupplywillbeimpactedbychangesinseasonality,increasedvarianceofecosystemproductivity,increasedsupplyrisksandreducedsupplypredictability–issuesthatmayalsohavelargeimpactsonsupplychaincostsandtheirflexibilitytorespondtovariation.Accesstofishforfoodwillbeaffectedbychangesinthedistribu-tionoffishspeciesandinlivelihoodscombinedwithtransferredimpactsfromothersectors(increasesinpricesofsubstitutefoodproducts),competitionforsupply,andinformationasymmetries.Policiesandmeasurestacklingclimatechangeimpactsmayin-directlyhamperpeople’saccesstofoodbyconstrainingindividu-als’expressionoftheirentitlementsandrightstofood.Utilizationofnutrients(i.e.theirnutritionalvalue)fromfisheryproductswillbeaffectedthroughchangingsupplyqualityandmarketchaindisruptions.Insomecases,aperiodofadjust-mentwillberequiredtomovetospeciesthatarenottradition-allyconsumed.Theseissuesaremostcriticalforcountrieswithahighpercapitaconsumptionofaquaticproteins.Harmfulalgalblooms(HABs),whichaffectfisheries,andinsomecasesresultinmakingshellfishandfinfishtoxictohumansareexpectedtovaryinfrequency,distributionandtimingwithclimatechange.HABsareprimarilycomposedofdinoflagellates(algae/phytoplankton)thatcanswimupanddownthewatercol-00.300.601.201.804.00ormoreSpeciesturnoverChangeintheinitialspeciesrichnessin2005relativeto2001-2005average(high-rangeclimatechangescenario)BiodiversityimpactintensitySource:redrawnfromCheungW.W.L.etal.,2009.Figure23.56umn.Itispredictedthatwhenoceanicwatersbecomemorestrat-ified,thesealgaeareexpectedtosurvivebetterthanotherphy-toplankton,andthereforethefrequencyofharmfulalgalbloomeventscouldincrease(Mooreetal.,2008).Theirrangeisexpectedtoextendtohigherlatitudesasseatemperaturesriseduetocli-matechange.HABshavealreadybeenobservedmorefrequentlyinnorthernEurope(Tester,1994).ThetiminganddurationofHABeventsisalsopredictedtochangeasseatemperatureswillreachtheirmaximumearlierandforlongerperiodsoftime,withoptimalgrowingconditionslastinglonger(Mooreetal.,2008).Thesecombinedchangeswillexposemorepeopleforlongertimeperiodsandoverwidergeographicrangestothetoxinsassociatedwithharmfulalgalbloomseitherasaerosolsorasaccumulationsinshellfishandfinfish(Mooreetal.,2008).WHOARETHEMOSTVULNERABLETOCLIMATECHANGEIMPACTSONOCEANS?Asmentionedinthepreviouschapters,impactsontheoceansfromgrowingclimatechangearelikelytoincluderisingsealevels,increasingacidity,increasingfrequencyandintensityofextremeweatherevents,anddeclineinfisheries.Theimpactsofthesephysicalandbiologicalchangesonfisheriesandaquacul-turecommunitieswillbeasvariedasthechangesthemselves(FAO,2008;Cochraneetal.,2009).Bothnegativeandposi-tiveimpactscouldbeforeseen,theirstrengthdependingonthevulnerabilityofeachcommunity;combiningpotentialimpacts(sensitivityandexposure)andadaptivecapacity.Impactswouldbefeltthroughchangesincapture,productionandmarketingcosts,changesinsalespricesandpossibleincreasesinrisksofdamageorlossofinfrastructure,fishingandaquaculturetoolsandhousing.Fishery-dependentcommunitiesmayalsofaceincreasedvulnerabilityintermsoflessstablelivelihoods,de-creasesinavailabilityand/orqualityoffishforfood,andsafetyrisks,forexample,fishinginharsherweatherconditionsandfurtherfromtheirlandingsites.Impactsonaquaculturecouldalsobepositiveornegative,aris-ingfromdirectandindirectimpactsonthenaturalresourcestheyrequire,primarilywater,land,seed,feedandenergy.Asfisheriesprovidesignificantfeedandseedinputs,theimpactsofclimatechangeonthemwillalso,inturn,affecttheproductivityandprofitabilityofaquaculturesystems,thusjeopardizingfoodsecurity(Cochraneetal.,2009).Vulnerabilityofaquaculture-basedcommunitieswillstemfromtheirresourcedependencyandalsoontheirexposuretoextremeweatherevents.Climaticchangescouldincreasephysiologicalstressonculturedstock,whichwouldnotonlyaffectproductivitybutalsoincreasevulner-abilitytodiseases,inturnimposinghigherrisksandreducingreturnstofarmers.Interactionsbetweenfisheriesandaquacul-turesub-sectorscouldcreateotherimpacts,forexampleextremeweathereventsresultinginescapesoffarmedstockandcontrib-utingtopotentialreductionsingeneticdiversityofthewildstockandaffectingmarinebiodiversityandecosystemsmorewidely.Theseimpactswillbecombinedwithotheraspectsaffectingadaptivecapabilities,suchastheincreasedpressurethateverlargercoastalpopulationsplaceonresources,anypolitical,in-stitutionalandmanagementrigiditythatnegativelyimpactsoncommunities’adaptivestrategies,deficienciesinmonitoringandearly-warningsystemsorinemergencyandriskplanning,aswellasothernon-climatefactorssuchaspoverty,inequality,foodinsecurity,conflict,anddisease.Thedegradationofthesemarineecosystemsbyclimatechange,poorcoastalwastemanagement,aswellasfromunsustainablenaturalresourceextractionpracticesincludingbottomtrawling(UNEP,2008b),willimpactabroadrangeofaspectsoffoodandlivelihoodssecurity.Adaptationandmitigationtoensureimprovedintegratedcoastalandaquaticresourcemanagementisthereforeessentialbothforrestoringcarbonsinkcapacity,aswellasforhealth,livelihoods,incomesandfoodsecurity.57Source:E.H.Allisonetal,Vulnerabilityofnationaleconomiestotheimpactsofclimatechangesonfisheries,FishandFisheries,2009,10,pp.173-196.HighModerateLowVerylowNodataavailableVulnerabilityofnationaleconomiestopotentialclimate-inducedchangesinfisheries19ofthe33countriesincludedintheHighVulnerabilityclassareLeastDevelopedCountries.Forsomeofthemoststronglyfisherydependentcountries(Benin,Chad,Comoros,Maldives,theRepublicofKorea,SãoToméandPrincipe)vulnerabilitydataarenotavailable.Thevulnerabilityofnationaleconomiestopotentialclimatechangeimpactsonfisherieswascalculatedcombiningcompositeindicatorsthatevaluatetheadaptivecapacityofcountries,theirexposuretoclimatechangeandtheirfisheriesdependence.Theadaptivecapacityindicatoriscalculatedfromindexesofhealth,education,governanceandsizeofeconomy.Thecountry-specificmeansurfacetemperatureincreaseby2050forIPCCscenarioB2(localdevelopment,loweremissions)wasconsideredasindicatorofexposuretoclimatechange.Theindicatoroffisheriesdependencewasdeducedfromthenationalnumberoffishers(absoluteandrelativetothelabourforce)andlandings,theincomedependencyonfisheries-derivedexportsandpercapitafishproteinsasaproportionoftotalanimalproteinsconsumed.Figure24:Comparativevulnerabilityofna-tionaleconomiestoclimateimpactsonfish-eries.Vulnerabilityofnationaleconomiesofpotentialclimatechangeimpactsonfisher-ies(whichintegratesexposure,sensitivityandadaptivecapacity)underIPCCscenarioB2(localdevelopment,loweremissions).585960Recognizingthathealthyandproductivecoastalecosystems,alreadyincreasinglystressedbyland-basedsourcesofpollution,coastaldevelopment,andhabitatdestruction,haveagrowingroleinmitigatingtheeffectsofclimatechangeoncoastalcommunitiesandeconomiesinthenearterm…Westresstheneedforsustainablemanagementofcoastalandmarineecosystems,includingmangrove,wetland,seagrass,andcoralreefs,asprotectiveandproductivebufferzonesthatdelivervaluableecosystemgoodsandservicesthathavesignificantpotentialforaddressingtheadverseeffectsofclimatechange.TheManadoDeclaration(WOC,2009).61Thereisincreasingawarenessandevidenceofthepotentialofrestoringnaturaleco­systemsasawaytomitigateclimatechange,butalsoensuringthecontinuedflowofecosystemservices(MA,2005;Trumperetal.,2009).Theseservices,including,butnotlimitedto,extremeweatherandtsunamibufferingeffects,enhancedfoodsupply,pollu­tionmitigationandhealthissues,aremainlyconcentratedinthecoastalzoneofoceans(UNEP,2006;2008b).Indeed,oceansbluecarbonsinks,alongwithcoralreefsandkelpcommunities,allfulfilveryimportantfunctionsinthecoastalzonewhileprovidingop­portunitiesforjobsandcoastalprosperity.ECOSYSTEM-BASEDADAPTATIONANDMITIGATIONUnfortunately,bluecarbonsinksaredisappearingatanalarmingrate.Humanactivitiessuchasdeforestation,pol-lutionbynutrientsandchemicalsfromagriculturalandin-dustrialrunoff,unsustainablecoastaldevelopment,overfish-ing,invasivespeciesinfestations,oilspills,dredging,fillingordrainagethatcausesediment-loading,mining,andlossofbiodiversityareimpactingcoastalecosystemsworldwide,farexceedingthenaturalbufferingcapacityoftheseecosystems(UNEP,2006;2008b).MANAGEMENTOFBLUECARBONSINKSANDTHEIRRESTORATIONBluecarbonsinksarehotspotsforcarbonburialintheoceanwheretheyplayagloballysignificantrolethatneedsbeincor-poratedintocurrentinventoriesofnaturalcarbonsinks.Abouthalfoftheirsinkcapacitymayhavebeenlostalready,mainlythroughthelossofthesevegetatedcoastalhabitatssincethe1940s.Effortstorecoverthecapacityofbluecarbonsinksneedsbeincorporatedincurrentstrategiestomitigateclimatechange,thusprovidinganimpetusforrestorationefforts.Therecoveryofbluecarbonsinkswillhelpcountriesmitigatetheircarbonemissionswhilerestoringvaluableecosystemservicesandkeynaturalresources.Integratedcoastalmanagementwillbecomecentralinthisprocesstoensureboththecarbonbind-ingcapacityandthegoodsandservicesrenderedforfoodse-curity,coastallivelihoodsandsustainablecoastaldevelopment.Thereissufficientevidencethatreversingtheglobaldeclineofvegetatedcoastalhabitatsandrecoveringthelostareaofbluecar-bonsinkswouldprovideaverylargeimprovementintheecologi-calstatusoftheglobalcoastalenvironment.Thiscouldresultintherecoveryofimportantservices,suchastheircapacitytooxy-genatecoastalwaters,serveasnurseries,helpingrestoreworldfishstocks,orsheltertheshorelinefromstormsandextremeweatherevents(HemmingaandDuarte2000;Danielsenetal.,2005).Atthesametimebystoppingthelossanddegradation,wewouldrebuildanimportantnaturalcarbonsink,therebycontrib-utingtomitigatingCO2emissionsand,hence,climatechange.Becausebluecarbonsinksoccuralongtheshorelinesofallcontinents,excepttheAntarctic,statesinregionswithexten-siveshallowcoastalareasacrosstheworld(e.g.India,southeastAsia,BlackSea,WestAfrica,Caribbean,Mediterranean,easternUSA,Russia)couldexplorethepotentialtomitigateCO2emissionsandimprovetheircoastalresourcesbypro-tectingandrestoringtheirbluecarbonsinks.Expandingbluecarbonsinksis,therefore,awin-winstrategy,(comparabletostrategiesinplacetoprotectandrebuildthecarbonsinkcapac-ityofrainforests)which,helpstoaddressthecommitmentsofstatesunderboththeBiologicalDiversityandClimateChangeConventionsoftheUN.Forinstance,theongoingnationalwet-landconservationactionplaninChinahasbeenestimatedtoinvolveapotentialforincreasedcarbonsequestrationby6.5762GgCyear–1(Xiaonanaetal.,2008).Andrewsetal.(2008)cal-culatedthattheneteffectofreturningofreturningsome26sqkmofreclaimedlandintheUKtointertidalenvironmentscouldresultintheburialofabout800tCyear−1.Afirststepistheprotectionoftheseimportantbluecarbonsinkhabitats,alreadyinplaceinmanycountries(e.g.EUmembers,USA,amongothers).Thisinvolvestheregulationofactivitiesresponsiblefortheirgloballoss,includingcoastalreclamation,deforestationofmangroveforests,excessfertilizerapplicationonlandcropsandinputsofurbanorganicwaste,siltationde-rivedfromdeforestationonland,unsustainablefishingandfix-ingofcoastlinesthroughcoastaldevelopment(Duarte,2002;2009).Bestpracticesforthemanagementofbluecarbonsinksareavailabletohelpmaintaintheseecosystemshealthywhilepreservingtheirfunctions(e.g.Borumetal.,2004;HamiltonandSnedaker1984;Melanaetal.,2000).Asecondstepshouldinvolveeffortsforthelarge-scaleresto-rationofthelostarea,whichisprobablyofthesameorder(ifnotlarger)thantheareacurrentlystillcoveredbytheseaquatichabitats(Duarte2009;Waycottetal.,2009).Forin-stance,somecountriesinSEAsiahavelostalmost90%oftheirmangrovessincethe1940s(Valielaetal.,2001).Large-scalerestorationprojectshavebeensuccessfullyconductedformangroves.Thesinglelargesteffortprobablybeingtheaffor-estationoftheMekongDeltaforestinVietnam,completelyde-stroyedbytheuseofAgentOrangeinthe1970’sandreplant-edbytheVietnamesepeople(Arnaud-Haondetal.,inpress).Salt-marshrestorationisalsopossibleandhasbeenappliedlargelyinEuropeandtheUSA(e.g.BoormanandHazelden1995).Restoringlostseagrassmeadowsismorecomplex,asthelabourrequiredtoinserttransplantsunderthewaterin-creasescost.Seagrassrestorationprojectshaveconsequentlyremainedcomparativelylimitedinsize(afewhectares)andnumber.Howeveritisaviableoptionprovidedthebenefitsofseagrassrestorationcanbeusedstrategically,forexampletocatalyzethegreatpotentialfornaturalrecovery.Thisisaslowprocesswhenunassisted(Duarteetal.,2005b),sohastobesupportedinparallelwithactionstoremovethepressuresthatcausedthelossinthefirstplace.Sucheffortswouldprovideinitialsourcesofgrowthandsubsequentlybenefitfromthe63exponentialcapacityofseagrassmeadowstoexpand,throughthegrowthoftheirrhizomes,overtheseafloor.Whilegreenfor-estcanonlygrowupwards,seagrassescanspreadhorizontallyatexponentialrates.Thesequestrationcapacityofindividualmarineecosystemsvar-iessubstantially(Table1).Notallbluecarbonsinksareequallyeffective,withsaltmarsheshavingthehighestcarbonburialrateperunitarea,followedbymangrovesandseagrass.Ourcurrentunderstandingofwhatdrivesahighcapacityforbluecarbonsinkecosystemsincludeshighbiomassandproduction,wheretheplantsproducelargesurplusoforganiccarbon(DuarteandCebrián,1996),andtheirlocationinanareawhereland-basedmaterialscanbeintercepted,addingtotheself-derivedsurplustoresultinlargecarbonburialrates(Bouillonetal.,2008).Res-torationeffortsmustfocusontherecoveryofbluecarbonsinkswithhighsequestrationcapacity,consideringthesedriversandcatalyzingthecapacityoftheseecosystemstoactasefficientcar-bonsinks.Additionalresearchontheconditionsthatresultinhighcarbonsinkcapacityofvegetatedcoastalhabitatscanhelpguidesuccessfulrestorationprojects.Mosteffortstorestorebluecarbonsinkshavebeendrivenbytheneedtorestorecoastalprotectionbyvegetatedhabitatsandtheirvalueashabitatsforkeyspecies(BoormanandHazelden,1995;Fonsecaetal.,2000;Danielsenetal.,2005).Itistimethattheirbeneficialroleascarbonsinksisalsotakenintoaccountandtoincludethisineconomicassessmentsofthebenefitsofrestor-ingbluecarbonsinks.INTEGRATEDECOSYSTEMAPPROACHESImprovingtheresilienceofthecoastalandoceanscommunities,bothhumanandaquatic,totheimpactsofclimatechangewillbekeytosustainingtheroleoftheoceansasprovidersoffoodandlivelihoodsecurity.Comprehensiveandintegratedecosys-temapproachestomanagingcoasts,oceans,andusesofaquaticresourcesshouldformthebasisforclimatechangeadaptationandmitigationstrategiesastheyaddressthesocial,economic,ecologicalandgovernanceaspectsunderlyingvulnerabilitytoclimatechange.Suchintegratedapproacheswouldhelptolinkthemultiplesectorsdependingoncoastalandoceanresourcestothoseorganizationswithclimatechangeanddisasterriskman-agementresponsibilities;therebyassistinginclimateproofingsector-specificdevelopmentstrategiesaswellas‘mainstreaming’theaquatic-basedsectorsintoclimatechangestrategies.Asisthecaseinland-basedsectors,manymutuallyrein-forcingsynergiesandbenefitsexistamongmitigationac-tionsandoveralldevelopmentgoalsforcoastalandoceanresources.Thesebenefitsinclude,forexample,improvedfisheriesandaquacultureproductionsystems,biodiversityconservationthroughincreasingmangrovepopulations,andincreasedenergyefficiencyintheshippingsectors.Effortsshouldincludeareasofmutualbenefittofoodandlivelihoodsecurityandtheresponsibilitiesofthesesectorstoreduceandavoidemissionsaswellastoenhancenaturalremovalsofgreenhousegases.Inordertoavoidnegativetrade-offsbetweenadaptationandmitigationwithinandamongsectors,anecosystemapproachandsystem-wideevaluationandplanningofmiti-gationandadaptationstrategieswillneedtoincludedown-streamimpactsonothersectors.Itisveryclearfromthisreport,thatthecarbonsinkcapacityofthesevaluablecoastalecosystemsshouldprovidemassiveadditionalimpetusforimprovedintegratedcoastalzonemanagement,protectionandrestoration.Theissueofmarinecarbonsequestrationisattractinggrowingatten-tionglobally,andanewcollaborativereporttitled‘Themanagementofcoastalcarbonsinks’bytheInternationalUnionfortheConservationofNatureandNaturalEngland,furtherexaminestheissueincloserdetail.Thisreportdocumentsthelatestinformationfromworld-leadingscientistsonthecarbonmanagementpotentialofanumberofcoastalecosystems:tidalsaltmarshes,mangroves,seagrassmeadows,kelpforestsandcoralreefs.Itexploresthelatestscienceforeachecosystem,explorestheirroleinthecarboncycle,andoutlinesmanagementop-tionsthatwouldmaintainandenhancethecarbonsinkingcapabilityofeachecosystem.Thisreportisplannedreleasedlaterthisyear(2009).Themanagementofcoastalcarbonsinks–aforthcomingIUCN/NaturalEngland/UNEPreport6465Inthediscussionsonclimatechange,marineecosystemshavenotreceivedsufficientattentionconsideringtheirimportanceforbothmitigationandadaptation.Amajorcon­tributingfactorhasbeenthecomplexityofmarineecosystems,theirstatusasaninterna­tionalandcommonpropertyresource,andtheabsenceofrobustmitigationmetrics.POLICYOPTIONSWhilenumeroustechnicalissuesawaitfullscientificandpoliti-calconsensus,internationalclimatechangeinstrumentsneedtoremainopentothedevelopmentofagreedmechanismsandmeasureswhichsupportmarineecosystemcoherenceandre-silienceandbuildonthestrongsynergiesbetweenmitigationandadaptation.Marineecosystemshave,untilveryrecently,beenvastlyover-lookedinclimatechangemitigationandadaptationdebates.To-day’seconomiesaremainlybasedonburningoffossilfuels.Formanycountries,therewillbemajorchallengesindevelopingindustryandexpandingtransportwhilereducingemissions.Itisabsolutelycriticalthatwhileemissionreductionsofbrownandblackcarbonaremade,wemustalsomaintain,andexpand,theabilityofthebiosphere,andinparticulartheoceans,tocon-tinuetocaptureandbindthecarbonthatweemit.Thereisanurgentneedfornewwaystoreducetheimpactofcontinuingemissions,notjustbyadapting,butalsobyensuringthatasmuchcarbonaspossibleistakenupbythenaturalsystem–andstored.Oceanshaveactedasoneofthelargestnaturalcarbonsinksthroughouthistoryandtheirabilitytocontinuethisroleshouldbeenhanced.Awordofcautionis,however,warranted:thereisno‘goldenkey’tosolveallproblems.Newinnovateshort-termsolutions,includinggeo-engineeringoptionssuchasfertilizingtheoceansorpumpingCO2intothedeepseasraiseseriousecological,economic,politicalandethicalchallenges,withmanyunknownvariablesandhighriskofpotentialsideef-fects(seeFactbox5).Theseproposalsshouldnotbedismissed,butbeforebeingoperationalizedonalargeorcommercialscale,moreresearchandcareful,thoroughevaluationisrequired.Optionsthatcanbothreduceandmitigateclimatechange,in-creasefoodsecurity,benefithealthandsubsequentproductiv-ityandgeneratejobsandbusinessarethereforeofmajorim-portance.Thisiscontrarytotheperceptionthatmitigationoremissionreductionisseenasacostandnotaninvestment.Im-provedintegratedmanagementofthecoastalandmarineenvi-ronments,includingprotectionandrestorationofourocean’sbluecarbonsinks,providesoneofthestrongestwin-winmiti-gationeffortsknowntoday.Itmayprovidevalue-addedbenefitswellinexcessofitscost,buthasnotyetbeenrecognizedintheglobalprotocolsandcarbontradingsystems.Bluecarbonsinkscoveronlyafractionoftheworld’soceans–andyetarecriticalandamongthemosteffectivecarbonsinksknowntoday.Theyprovidevaluableecosystemservicesforfisheries,tourismandcoastaleconomies.Buttheyaredis-appearingataratehigherthananyotherecosystemonearth.Lessthantwodecadesremaintosecurethemandrestorethem,withimmediatecarbon-bindingeffectandimmediatereturnsintermsoffisheriesandaddedbenefitsfromimprovedshore-lineprotectionandecosystemservices.666768Themostrecentestimatesindicatethathumanactivitiesarecur-rentlyresponsibleforannualglobalcarbonemissionsofaround7–10,000TgCyr–1,ofwhicharound1,500TgCoraround15–20%istheresultoflandusechange.Theremainingemissionsarefromfossilfueluseandcementproduction(Canadelletal.,2007).ThishasledtoanaverageannualrateofincreaseofCO2concentrationsintheatmosphereof1–2ppmorupto2,000TgCyr–1fortheyears1995–2005comparedwitharound1.25ppmfortheyears1960–1995(IPCC,2007b;Houghton,2007).Greencarbon:Reducingdeforestationratesby50%by2050andthenmaintainingthematthisleveluntil2100wouldavoidthedirectreleaseofupto50GtCthiscenturyorapproximately555TgCyr–1,whichisequivalentto12–15%oftheemissionsreductionsneededtokeepatmosphericconcentrationsofcarbondioxidebelow450ppm(Trumperetal.,2009).Bluecarbon:Accordingtothisreport,protection,improvedman-agementandrestorationoftheocean’sbluecarbonsinkswouldresultinpreventingtheannuallossofupto450TgCyr–1,orequiva-lenttoacorresponding10%ofthereductionsneeded.Combinedwiththegreencarbon–REDD–theeffectwouldbeatleast20–25%oftheemissionreductionsneeded–withhugeben-efitstofoodsecurity,waterresources,biodiversity–andthecre-ationofjobsandincomes.Butthiswouldrequireasimilar“REDD”programmeforoceansashasbeenestablishedforrainforests–abluecarbonfund.Factbox8.A25%emissionreductioncouldbegainedfromgreenandbluecarbon69Establishaglobalbluecarbonfundforprotectionandmanagementofcoastalandmarineecosys-temsandoceancarbonsequestration.a.Withininternationalclimatechangepolicyinstruments,cre-atemechanismstoallowthefutureuseofcarboncreditsformarineandcoastalecosystemcarboncaptureandeffectivestor-ageasacceptablemetricsbecomeavailable.Bluecarboncouldbetradedandhandledinasimilarwaytogreencarbon–suchasrainforests–andenteredintoemissionandclimatemitiga-tionprotocolsalongwithothercarbon-bindingecosystems;b.Establishbaselinesandmetricsforfutureenvironmentallysoundoceancarboncaptureandsequestration;c.Considertheestablishmentofenhancedcoordinationandfundingmechanisms;d.Upscaleandprioritizesustainable,integratedandecosys-tem-basedcoastalzoneplanningandmanagement,especiallyinhotspotswithinthevicinityofbluecarbonsinkstoincreasetheresilienceofthesenaturalsystemsandmaintainfoodandlivelihoodsecurityfromtheoceans.Immediatelyandurgentlyprotectatleast80%ofremainingseagrassmeadows,saltmarshesandmangroveforests,througheffectivemanagement.Futurefundsforcarbonsequestrationcancontributetomain-tainingmanagementandenforcement.Initiatemanagementpracticesthatreduceandre-movethreats,andwhichsupporttherobustrecoverypotentialinherentinbluecarbonsinkcommunities.Maintainfoodandlivelihoodsecurityfromtheoceansbyimplementingcomprehensiveandinte-gratedecosystemapproachesaimingtoincreasetheresilienceofhumanandnaturalsystemstochange.Implementwin-winmitigationstrategiesintheocean-basedsectors,includingto:a.Improveenergyefficiencyinmarinetransport,fish-ingandaquaculturesectorsaswellasmarine-basedtourism;b.Encouragesustainable,environmentallysoundoceanbasedenergyproduction,includingalgaeandseaweed;c.Curtailactivitiesthatnegativelyimpacttheocean’sabilitytoabsorbcarbon;d.Ensurethatinvestmentforrestoringandprotectingtheca-pacityofocean’sbluecarbonsinkstobindcarbonandprovidefoodandincomesisprioritizedinamannerthatalsopromotesbusiness,jobsandcoastaldevelopmentopportunities;e.Catalyzethenaturalcapacityofbluecarbonsinkstoregener-atebymanagingcoastalecosystemsforconditionsconducivetorapidgrowthandexpansionofseagrass,mangroves,andsaltmarshes.15432Inordertoimplementaprocessandmanagethenecessaryfundsfortheprotection,managementandrestorationofthesecrucialoceancarbonsinks,thefollowingoptionsareproposed:KEYOPTIONS:70GLOSSARYAcidificationSeeOceanacidification.AfforestationAfforestationisdefinedundertheKyotoProtocolasthedirecthuman-inducedconversionofnon-forestlandtopermanentfor-estedland(foraperiodofatleast50years)(Angelsen2008).ArchaeaUnique,singlecelledorganismswhicharegeneticallyandmet-abolicallydistinctfrombacteria.AutotrophicOforrelatingtoanautotroph,anorganismcapableofmakingnutritiveorganicmoleculesfrominorganicsourcesviaphoto-synthesis(involvinglightenergy)orchemosynthesis(involvingchemicalenergy).BiofuelAnyliquid,gaseous,orsolidfuelproducedfromplantorani-malorganicmatter.e.g.soybeanoil,alcoholfromfermentedsugar,blackliquorfromthepapermanufacturingprocess,woodasfuel,etc.Second-generationbiofuelsareproductssuchasethanolandbiodieselderivedfromligno-cellulosicbiomassbychemicalorbiologicalprocesses(IPCC2007a).CoastaloceanTheregionextendingfromthebeachesoutacrosstheconti-nentalshelf,slope,andrise(Brink,1993).CarbonCaptureandStorage(CCS)AprocessconsistingofseparationofCO2fromindustrialandenergy-relatedsources,transporttoastoragelocation,andlongtermisolationfromtheatmosphere(IPCC,2007a).CarboncycleThetermusedtodescribetheflowofcarbon(invariousforms,e.g.,ascarbondioxide)throughtheatmosphere,ocean,terres-trialbiosphereandlithosphere(IPCC2007c).CarbonsequestrationTheprocessofincreasingthecarboncontentofareservoirotherthantheatmosphere(Chopraetal.2005).CarbonsinkSeeSink.CarbonsourceSeeSource.CleanDevelopmentMechanism(CDM)AmechanismundertheKyotoProtocoldesignedtoassistde-veloped(AnnexI)countriesinmeetingtheiremissionsreduc-tiontargets.Themechanismreducesemissionsthroughimple-mentingprojectsindeveloping(AnnexII)countrieswhicharecreditedtotheAnnexIcountrieswhofinanceandimplementtheproject.TheCDMaimstonotonlyreduceemissionsorin-creasesinksbutalsocontributetothesustainabledevelopmentofthehostcountry(Peskettetal.2008).GreenhousegasesGreenhousegasesarethosegaseousconstituentsoftheatmo-sphere,bothnaturalandanthropogenic,thatabsorbandemitradiationatspecificwavelengthswithinthespectrumofinfra-redradiationemittedbytheearth’ssurface,theatmosphereandclouds.Thispropertycausesthegreenhouseeffect.Watervapour(H2O),carbondioxide(CO2),nitrousoxide(N2O),meth-ane(CH4)andozone(O3)aretheprimarygreenhousegasesintheearth’satmosphere(IPCC2007a).KyotoProtocolAnagreementmadeundertheUnitedNationsFrameworkConventiononClimateChange(UNFCCC).Countriesthatratifythisprotocolcommittoreducingtheiremissionsofcar-bondioxideandfiveothergreenhousegases(GHG),orengag-inginemissionstradingiftheymaintainorincreaseemis-sionsofthesegases.TheKyotoProtocolnowcoversmorethan170countriesgloballybutonly60%ofcountriesintermsofglobalgreenhousegasemissions.AsofDecember2007,theUSandKazakhstanaretheonlysignatorynationsnottohaveratifiedtheact.ThefirstcommitmentperiodoftheKyotoPro-tocolendsin2012,andinternationaltalksbeganinMay2007onasubsequentcommitmentperiod(Peskettetal.2008).LandUse,LandUseChangeandForestry(LULUCF)Agreenhousegasinventorysectorthatcoversemissionsandremovalsofgreenhousegasesresultingfromdirecthuman-71inducedlanduse,land-usechangeandforestryactivities(UN-FCCC2009).LeakageInthecontextofclimatechange,carbonleakageistheresultofinterventionstoreduceemissionsinonegeographicalarea(subnationalornational)thatleadtoanincreaseinemissionsinanotherarea.Forexample,ifcurbingtheencroachmentofagricultureintoforestsinoneregionresultsinconversionofforeststoagricultureinanotherregionthisisconsideredtobe“leakage”.InthecontextofREDD,leakageisalsoreferredtoas‘emissionsdisplacement’(Angelsen2008).MitigationAhumaninterventiontoreducethesourcesoforenhancethesinksforgreenhousegases(DepartmentofClimateChange2008).OceanacidificationAdecreaseinthepHofseawaterduetotheuptakeofanthro-pogeniccarbondioxide(IPCC2007c).OpenoceanWherethewaterdepthexceeds200maroundtheboundariesofthemajorcontinentallandmasses.Thisdefinitionexcludesthemarginalenclosedandsemi-enclosedseas,butincludesalloceanregionsborderinglesserislandsystemsregardlessofwa-terdepth(UNEPandIOC-UNESCO,2009).PermanenceThedurationandnon-reversibilityofareductioninGHGemis-sions(Angelsen2008).Thisisanissueinthelandusesectorascar-bonstoredandsequesteredinecosystemsistheoreticallyalwaysvulnerabletoreleaseatsomeundeterminedpointinthefuture.ReforestationReforestationis“thedirecthuman-inducedconversionofnon-forestedlandtoforestedlandthroughplanting,seedingand/orthehuman-inducedpromotionofnaturalseedsources,onlandthatwasforested,butthathasbeenconvertedtonon-forestedland”.InthefirstcommitmentperiodoftheKyotoProtocol,re-forestationactivitieshavebeendefinedasreforestationoflandsthatwerenotforestedon31December1989,buthavehadforestcoveratsomepointduringthepast50years(Angelsen2008).RespirationTheprocesswherebylivingorganismsconvertorganicmattertocarbondioxide,releasingenergyandconsumingmolecularoxygen(IPCC2007c).SequestrationTheremovalofatmosphericcarbondioxide,eitherthroughbiologicalprocesses(forexample,photosynthesisinplantsandtrees,seeBiosequestration),orgeologicalprocesses(forexample,storageofcarbondioxideinundergroundreservoirs)(DepartmentofClimateChange2008).SinkAnyprocess,activityormechanismthatremovesagreenhousegas,anaerosoloraprecursorofagreenhousegasoraerosolfromtheatmosphere(IPCC2007c).SourceAnyprocess,activityormechanismthatreleasesagreenhousegas,anaerosoloraprecursorofagreenhousegasoraerosolintotheatmosphere(IPCC2007c).SustainabilityAcharacteristicorstatewherebytheneedsofthepresentandlocalpopulationcanbemetwithoutcompromisingtheabilityoffuturegenerationsorpopulationsinotherlocationstomeettheirneeds(Chopraetal.2005).UnitedNationsFrameworkConventiononClimateChange(UNFCCC)TheUnitedNationsFrameworkConventiononClimateChange(UNFCCC)isthefirstinternationalclimatetreaty.Itcameintoforcein1994andhassincebeenratifiedby189countriesincludingtheUnitedStates.Morerecently,anumberofnationshaveapprovedanadditiontothetreaty:theKyotoProtocol,whichhasmorepowerful(andlegallybinding)mea-sures(Kirby2008).UNFCCCSeeUnitedNationsFrameworkConventiononClimateChange.72ACRONYMSCCDMCO2EU-ETSFAOGEFGHGGRIDHABHCO3–HClMEDEAIPCC°CppmREDDREDD-PlusSIDSSOCTCyr–1TgCyr–1UNEPUNEP-WCMCUNESCOIOC-UNESCOUSAUSDyr–1CarbonCleanDevelopmentMechanismCarbondioxideTheEmissionsTradingSystemoftheEuropeanUnionFoodandAgricultureOrganizationoftheUNGlobalEnvironmentFacilityGreenhousegasGlobalResourceInformationDatabaseHarmfulAlgalBloomBicarbonateionHydrochloricacidMediterraneanInstituteofAdvancedStudiesIntergovernmentalPanelonClimateChangeDegreescentigradePartspermillionUnitedNationsCollaborativeProgrammeonReducingEmissionsfromDeforestationandForestDegradationinDevelopingCountriesReducingemissionsfromdeforestationanddegradation,conservationofexistingcarbonstocksandenhancementofcarbonstocksSmallIslandDevelopingStatesSedimentaryorganiccarbonTonnesofcarbonperyearTeragramsofcarbonperyearUnitedNationsEnvironmentProgrammeUNEP-WorldConservationMonitoringCentreUnitedNationsEducational,ScientificandCulturalOrganisationIntergovernmentalOceanographicCommissionofUNESCOUnitedStatesofAmericaUSDollarsperyearPHOTOCREDITS1iStockphoto/FelixMöckel1iStockphoto/NicholasMonu4iStockphoto/JanRysavy9iStockphoto/AndriyMyahkov10iStockphoto/JudsonAbts14iStockphoto/SusannaPershern18–19ManuSanFelix20iStockphoto/KeiichiHiki20iStockphoto/DavidParsons20iStockphoto/JurgaR20–21iStockphoto/TammyPeluso28iStockphoto/JohnKounadeas29iStockphoto/thp7334iStockphoto/SharonMetson38–39CarlosM.Duarte40iStockphoto/JarosławJuszkiewicz44iStockphoto/HaiderYousuf48iStockphoto/SuzanaProfeta49JacquelineAlder50iStockphoto/brytta53iStockphoto/RainforestAgencies56iStockphoto/ThomasBradford58–59OCEANA/JuanCuetos59OCEANA/MarMas59OCEANA/JuanCuetos60iStockphoto/jacus62iStockphoto/LesleyJacques63iStockphoto/OmarAriff64JenniferWolf/WolfHarttImage/MarinePhotobank66TophamPicturepoint/UNEP/DavidTapiaMunoz66iStockphoto/SergeyDubrovskiy66iStockphoto/AntonioD’Albore67iStockphoto/SerdarYagci67iStockphoto/GalinaBarskaya67iStockphoto/pidjoe68MohNurHarun/MarinePhotobank79iStockphoto/MariaPavlova80iStockphoto/ValentinCasarsa73CONTRIBUTORSANDREVIEWERSEDITORSChristianNellemann,EmilyCorcoran,CarlosM.Duarte,LuisVal-dés,CassandraDeYoung,LucianoFonseca,GabrielGrimsditchCONTRIBUTORSTarubBahriFoodandAgricultureOrganisationoftheUnitedNations,VialedelleTermediCaracalla,00153Roma,ItaliaCarlosM.DuarteDepartmentofGlobalChangeResearch.IMEDEA(CSIC-UIB)InstitutMediterránid’EstudisAvançats,MiquelMarqués21,Espor-les,SpainCassandraDeYoung,DorisSotoFoodandAgricultureOrganisationoftheUnitedNations,VialedelleTermediCaracalla,00153Roma,ItaliaChristianNellemann,EmilyCorcoran,RiccardoPravettoni,PetterSevaldsenUNEP/GRID-Arendal,Teaterplassen3,4836Arendal,Norway,www.grida.noJacquelineAlder,OleVestergaard,GabrielGrimsditchUnitedNationsEnvironmentProgramme,DivisionforEnviron-mentalPolicyImplemnentation,UnitedNationsAvenue,Gigiri,POBox30552,00100Nairobi,KenyaLuisValdés,LucianoFonsecaIntergovernmentalOceanographicCommissionofUNESCO,1rueMiollis,75732ParisCedex15,FranceNicoleGlineurGlobalEnvironmentFacility,BiodiversityandPrivateSectorGEFSecretariat,1818HStreet,NW,MSNG6-602,Washington,DC20433,USAPavanSukhdevGreenEconomyInitiative(UNEP),219HuntingdonRoad,Cam-bridge,CB30DL,UKStefanHain,CorinnaRavilious,TerriYoungUNEPWorldConservationMonitoringCentre(UNEP-WCMC),219HuntingdonRoad,Cambridge,CB30DL,UKWilliamCheungSchoolofEnvironmentSciences,UniversityofEastAngliaNor-wich,NR47TJ,UKCarl-GustafLundinInternationalUnionfortheConservationofNature(IUCN)GlobalMarineProgramme,RueMauverney28,CH-1196Gland,SwitzerlandCARTOGRAPHYRiccardoPravettoniGiulioFrigieri(Figures6and24)REVIEWERSElaineBaker,Jean-NicolasPoussart,MortenSørensenUNEP/GRID-Arendal,Teaterplassen3,4836Arendal,Norway,www.grida.noRobKayCoastalZoneManagement(Australia)PtyLtd,POBox436,Clare-mont,Perth,Australia,6010ChrisTompkinsIndependentConsultantRichardKenchingtonRACMarinePtyLtd,P.O.Box588,Jamison,ACT2614,AustraliaKieranKelleherTheWorldBank,WashingtonD.C.20433,USAFrancineKershawUNEPWorldConservationMonitoringCentre(UNEP-WCMC),219HuntingdonRoad,Cambridge,CB30DL,UKJamesSpurgeon,EnvironmentalResourcesManagement,EatonHouse,WallbrookCourt,NorthHinkseyLane,Oxford,OX20QS,UKDavidOsbourneUnitedNationsEnvironmentProgramme,DivisionforEnviron-mentalPolicyImplemnentation,UnitedNationsAvenue,Gigiri,POBox30552,00100Nairobi,KenyaGailM.ChmuraMcGillUniversity,DepartmentofGeography,805SherbrookeStW,Montreal,QCH3A2K6CanadaIngunnVistnesNorutAlta–Áltá,Postboks1463,N-9506Alta,NorwayCOPYEDITORSAniaNiedzwiadek,CarmenElricknCoastalZoneManagement,PtyLtd,POBox436,Claremont,Perth,Australia,6910HarryForsterInterrelate,2,rueSaintLaurent,38000Grenoble,France74REFERENCESAchard,F.,H.D.Eva,H.J.Stibig,P.Ayaux,J.Gallego,T.RichardsandJ.P.Malingreau.2002.DeterminationofDeforestationRatesoftheWorld’sHumidTropicalForests.Science297:999-1002.Allison,E.H.,A.L.Perry,M.C.Badjeck,W.N.Adger,K.Brown,D.Con-way,A.S.Halls,G.M.Pilling,J.D.Reynolds,N.L.AndrewandN.K.Dulvy.2009.Vulnerabilityofnationaleconomiestotheimpactsofclimatechangeonfisheries.FishandFisheries.Andrews,J.E.,G.SamwaysandG.B.Shimmield.2008.Historicalstor-agebudgetsoforganiccarbon,nutrientandcontaminantelementsinsaltmarshsediments:Biogeochemicalcontextformanagedrealignment,HumberEstuary,UK.ScienceofTheTotalEnvironment405:1-13Angelsen,A.(Ed.).2008.MovingaheadwithREDD:Issues,optionsandimplications.CIFOR:Bogor,Indonesia.Arnaud-Haond,S.,C.M.Duarte,S.Teixeira,S.I.Massa,J.Terrados,N.HongTri,P.N.Hong,E.A.Serrao.2009.Geneticrecolonizationofman-grove:geneticdiversitystillincreasingintheMekongDelta30yearsafterAgentOrange.MarineEcologyProgressSeries(inpress).Arrigo,K.R.2005.Marinemicro-organismsandglobalnutrientcycles.Nature,437:7057p349.doi:10.1038/nature04159Beja,O.,E.N.Spudich,J.L.Spudich,M.Leclerc,andE.F.DeLong.2001.Proteorhodopsinphototrophyintheocean.Nature,411:786-789.Bender,M.L.,D.T.Ho,M.B.Hendricks,R.Mika,M.O.Battle,P.P.Tans,T.J.Conway,B.SturtevantandN.Cassar.2005.AtmosphericO2/N2changes,1993–2002:ImplicationsforthepartitioningoffossilfuelCO2sequestration,GlobalBiogeochem.Cy.,19,GB4017,doi:10.1029/2004GB002410,2005.Bishop,J.K.B.,andT.J.Wood.2009.Year-roundobservationsofcarbonbiomassandfluxvariabilityintheSouthernOcean,GlobalBiogeochem.Cycles,23,GB2019,doi:10.1029/2008GB003206Bond,C.,etal.2000.Atechnology-basedglobalinventoryofblackandorganiccarbonemissionsfromcombustion.Boorman,L.andJ.Hazelden,1995.Saltmarshcreationandmanage-mentforcoastaldefence,in:Healy,M.G.;Doody,J.P.(1995).DirectionsinEuropeancoastalmanagement.pp.175-183Borum,J.,C.M.Duarte,D.Krause-JensenandT.M.Greve.2004.Eu-ropeanseagrasses:anintroductiontomonitoringandmanagement.TheM&MSproject,Copenhagen.ISBN:87-89143-21-3,95p.Bouillon,S.,A.V.Borges,E.Castañeda-Moya,K.Diele,T.Dittmar,N.C.Duke,E.Kristensen,S.Y.Lee,C.Marchand,J.J.Middelburg,V.H.Rivera-Monroy,T.J.SmithIII,andR.R.Twilley.2008.Mangroveproductionandcarbonsinks:ArevisionofglobalBudgetestimates.GlobalBiogeochemicalCycles22:GB2013,doi:10.1029/2007GB003052.Bowler,C.,D.M.Karl,R.R.Colwell.2009.Microbialoceanographyinaseaofopportunity.Nature459:180-184Bridgham,S.D.,J.P.Megonigal,J.K.Keller,N.B.Bliss,andC.Trettin.2006.ThecarbonbalanceofNorthAmericanwetlands.Wetlands26:889–916.Brink,K.H.1993.Thecoastaloceanprocesses(CoOP)effort.Oceanus,March22,1993Burkill,P.H.,S.D.Archer,C.Robinson,P.D.Nightingale,S.B.Groom,G.A.TarranandM.V.Zubkov.2002.Dimethylsulphidebiogeochemistrywithinacoccolithophorebloom(DISCO):anoverview.DeepSeaResearchII49(15):2863-2885Campy,MandJ.J.Macaire.2003.GéologiedelaSurface:Érosion,trans-fertetstockagedanslesenvironnementscontinentaux,Duno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