iap statement
TRANSCRIPT
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8/9/2019 IAP Statement
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IAP STATEMENT ON OCEAN ACIDIFICATION
Headline messages
OceansplayacriticalroleintheglobalcarboncyclebyabsorbingaboutaquarterotheCO2emittedtotheatmosphereromhumanactivities;
TherapidincreaseinCO2emissionssincetheindustrialrevolutionhasincreasedtheacidityotheworldsoceanswithpotentiallyprooundconsequencesormarineplantsandanimalsespeciallythosethatrequirecalciumcarbonatetogrowandsurvive,andotherspeciesthatrelyontheseorood;
Atcurrentemissionratesmodelssuggestthatallcoralreesandpolarecosystemswillbeseverelyaectedby2050orpotentiallyevenearlier;
Marineoodsuppliesarelikelytobereducedwithsignifcantimplicationsoroodproductionandsecurityinregionsdependentonfshprotein,andhumanhealthandwellbeing;
Oceanacidifcationisirreversibleontimescalesoatleasttensothousandsoyears;
EvenwithstabilisationoatmosphericCO2at450ppm,oceanacidifcationwillhaveprooundimpactsonmanymarinesystems.LargeandrapidreductionsoglobalCO 2emissionsareneededgloballybyatleast50%by2050.
1. CO2 and ocean chemistry
Overthepast200years,theoceanshaveabsorbedapproximatelyaquarterotheCO 2producedromhumanactivities.ThisCO2wouldotherwisehaveaccumulatedintheatmosphereleadingtogreaterclimatechange.However,theabsorptionothisCO2hasaectedoceanchemistryandhascausedtheoceans(whichareonaverageslightlyalkaline)tobecomemoreacidic.TheaveragepHooceanicsuracewatershasbeenloweredby0.1unitssincethepre-industrialperiod.Thisrepresentsa30%increaseinhydrogenionactivity.Hydrogenionsattackcarbonateionswhicharethebuildingblocksneededbymanymarineorganisms,suchascoralsandshellfsh,toproducetheirskeletons,shellsandotherhardstructures.Thislossocarbonateionsproducelowersaturationlevelsorthecarbonateminerals,aragoniteandcalcite,whichareusedinmanyshellsandskeletons.Carbonateionconcentrationsarenowlowerthanatanyothertimeduringthelast800000years.
GlobalatmosphericCO 2concentrationsarenowat387ppm.IcurrenttrendsinCO 2emissionscontinue,modelprojectionssuggestthatbymid-centuryCO 2concentrationswillbemorethandoublepre-industriallevelsandtheoceanswillbemoreacidicthantheyhavebeenortensomillionsoyears.Thecurrentrateochangeismuchmorerapidthanduringanyeventoverthelast65millionyears.Thesechangesinoceanchemistryareirreversibleormanythousandsoyears,andthe
biologicalconsequencescouldlastmuchlonger.
2. Environmental damage rom ocean acidifcation
Oceanacidifcationimpactsonmarineliewilldependontherateandmagnitudeochangesinoceanchemistryandbiologicalresponses.Whiletheoceanchemistrychangesarepredictablewithhighcertainty,ourunderstandingotheimpactsisstilldeveloping.Nevertheless,thereisstrongevidenceemergingorarangeobiologicaleectsandchangesinthemarinebiogeochemicalprocessesthataectthecarboncycle.Thelong-termconsequencesothisaredifculttopredict.
Impactsarealreadybeingobservedinthepolarandtropicalregions.Coralcalcifcationrateshavedeclinedinrecentdecades,althoughattributingcausesortheseimpactsamongmultipledrivers(acidifcation,warming,pollution,etc.)isachallenge.FundamentalecologicaloceanprocesseswillbeaectedasmanymarineorganismsdependdirectlyorindirectlyoncalciumcarbonatesaturatedwatersandareadaptedtocurrentlevelsoseawaterpHorphysiologicalandmetabolicprocessessuchascalcifcation,growthandreproduction.ThepHchangesexpectedwillexceedtheseasonalandregional
variationscurrentlyexperiencednaturally.
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Oceanacidifcationisaglobalissue.However,changesinoceanchemistrywillberegionallyvariablewithsomeregionsaectedmorerapidlythanothers.ThehighCO 2watersinpolarandupwellingregionssuchastheeasternPacifcandBeringSeaorexample,willexperiencelowpHmorerapidlythanotherregions.Tropicalwaters,suchasthosearoundtheGreatBarrierReewillalsoexperiencerapiddeclinesinthecarbonateionsimportantorcoralreeconstruction.Accordingtorecentmodelprojectionsalmostalltropicalandsub-tropicalcoralreesweresurroundedbywatersavourabletocoralgrowthbeoretheindustrialrevolution.IatmosphericCO 2isstabilizedat450ppm,onlyaverysmallraction(~8%)oexistingtropicalandsubtropicalcoralreeswillbesurroundedbysuchwater,andat550ppm,coralreesmaybedissolvingglobally.Coldwatercoralsarealsovulnerableandarelikelytobeaectedbeoretheyhaveevenbeenullyexplored.By2100,ithasbeenestimatedthat70%willbeinwatersunavourableorgrowth.
Inthepolarregions,modelprojectionsusingcurrentCO 2emissionratessuggestthatpartsotheSouthernOceanwillbeundersaturatedoraragoniteby2050.Aragoniteundersaturationisprojectedor10%oArcticwatersbyaround2020,andby2060,80%owaterswillbeundersaturatedoraragoniteandcalcite.ThismeansthewaterswillbecorrosivetoArcticcalciferssuchaspteropods,andbivalvessuchasclams,whichplayakeyroleinArcticoodwebs.
Theoceanchemistrychangesprojectedwillexceedtherangeonaturalvariability,whichislikelytobetoorapidormanyspeciestoadaptto.Manycoastalanimalsandgroupsophytoplanktonandzooplanktonmaybedirectlyaectedwithimplicationsorfsh,marinemammalsandtheothergroupsthatdependonthemorood.IncreasedCO 2maybeparticularlystressulororganismswithhighmetabolicratessuchassquid.Theimpactsothesechangesonoceanicecosystemsandtheservicestheyprovide,orexampleinfsheries,coastalprotection,tourism,carbonsequestrationandclimateregulation,cannotyetbeestimatedaccuratelybuttheyarepotentiallylarge.
Althoughsomespeciesmaybeneft,mostareadaptedtocurrentconditionsandtheimpactsonoceanbiologicaldiversityandecosystemunctioningwilllikelybesevere.AnalysisopasteventsinEarthsgeologichistorysuggeststhatchemicalrecoverywilltaketensothousandsoyearswhiletherecoveryoecosystemunctionandbiologicaldiversitycantake
muchlonger.
4. Mitigation
Oceanacidifcationisirreversibleduringourlietimesandthoseomanygenerationstocome.Tominimisetheriskotheselarge-scaleandlong-termchangestotheoceanstheincreaseinatmosphericCO 2mustbecurbedbyreducingemissionsromhumanactivities.
RecentscenariostudieshaveestimatedthatstabilisationoatmosphericCO 2concentrationsat550ppmwillproduceenoughacidifcationtobedisastrousorsensitiveoceanicecosystemsinmanypartsotheworld.Evenat450ppm,morethan10%otheworldsoceanswillbeimpactedincludinglargepartsotheSouthern,NorthPacifc,andArcticoceans.
Mitigationapproachessuchasaddingchemicalstocountertheeectsoacidifcationarelikelytobeexpensive,onlypartlyeectiveandonlyataverylocalscale,andmayposeadditionalunanticipatedriskstothemarineenvironment.Therehasbeenverylittleresearchontheeasibilityandimpactsotheseapproaches.Substantialresearchisneededbeorethesetechniquescouldbeapplied.
5. Conclusions and recommendations
OceanacidifcationisadirectconsequenceoincreasingatmosphericCO 2concentrations.Toavoidsubstantialdamagetooceanecosystems,deepandrapidreductionsoglobalCO 2emissionsbyatleast50%by2050,andmuchmorethereaterareneeded.
We,theacademiesoscienceworkingthroughtheInterAcademyPanelonInternationalIssues(IAP),callonworldleadersto:
AcknowledgethatoceanacidifcationisadirectandrealconsequenceoincreasingatmosphericCO 2concentrations,isalreadyhavinganeectatcurrentconcentrations,andislikelytocausegraveharmtoimportantmarineecosystemsasCO2concentrationsreach450ppmandabove;
RecognisethatreducingthebuildupoCO2intheatmosphereistheonlypracticablesolutiontomitigatingocean
acidifcation;WithinthecontextotheUNFCCCnegotiationsintherunuptoCopenhagen2009,recognisethedirectthreatsposedbyincreasingatmosphericCO 2emissionstotheoceansandthereoresociety,andtakeactiontomitigatethisthreat;
ImplementactiontoreduceglobalCO2emissionsbyatleast50%o1990levelsby2050andcontinuetoreducethemthereater;
Reinvigorateactiontoreducestressors,suchasoverfshingandpollution,onmarineecosystemstoincreaseresiliencetooceanacidifcation.
Theollowingacademieshaveendorsedthisstatement.
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TWAS,theacademyosciencesorthedevelopingworld
AlbanianAcademyoSciences
NationalAcademyoExact,PhysicalandNaturalSciences,Argentina
AustralianAcademyoScience
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TheRoyalAcademiesorScienceandtheArtsoBelgium
BrazilianAcademyoSciences
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RSC:TheAcademiesoArts,HumanitiesandSciencesoCanada
AcademiaChilenadeCiencias
ChineseAcademyoSciences
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AcademyoSciencesotheCzechRepublic
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AcademyoScientifcResearchandTechnology,Egypt
TheDelegationotheFinnishAcademiesoScienceandLetters
AcadmiedesSciences,France
GeorgianAcademyoSciences
UnionderDeutschenAkademienderWissenschaten
DeutscheAkademiederNaturorscherLeopoldina
TheAcademyoAthens
AcademiadeCienciasMedicas,FisicasyNaturalesdeGuatemala
IndianNationalScienceAcademy
IndonesianAcademyoSciences
AcademyoSciencesotheIslamicRepublicoIran
RoyalIrishAcademy
IsraelAcademyoSciencesandHumanities
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ScienceCounciloJapan
RoyalScientifcSocietyoJordan
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KenyaNationalAcademyoSciences
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RoyalAcademyoExact,PhysicalandNaturalSciencesoSpain
NationalAcademyoSciences,SriLanka
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