WEATHERCLIMATEWATER

StateoftheClimateinAsia

2023O6

WMO-No.1350

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ISBN978-92-63-11350-4

Coverillustration:Yangtzeriver,YunnanProvince,China.Source:AdobeStock

NOTE

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Thefindings,interpretationsandconclusionsexpressedinWMOpublicationswithnamedauthorsarethoseoftheauthorsaloneanddonotnecessarilyreflectthoseofWMOoritsMembers.

Chair,PublicationsBoard

WorldMeteorologicalOrganization(WMO)

7bis,avenuedelaPaix

P.O.Box2300

CH-1211Geneva2,Switzerland

WMO-No.1350

?WorldMeteorologicalOrganization,2024

Therightofpublicationinprint,electronicandanyotherformandinanylanguageisreservedbyWMO.ShortextractsfromWMOpublicationsmaybereproducedwithoutauthorization,providedthatthecompletesourceisclearlyindicated.Editorialcorrespondenceandrequeststopublish,reproduceortranslatethispublicationinpartorinwholeshouldbeaddressedto:

B

i

Contents

Keymessages ii

Foreword iii

Preface iv

Globalclimatecontext 1

Regionalclimate 2

Temperature 2

Precipitation 4

Cryosphere 5

Sea-surfacetemperature 9

Oceanheatcontent 10

Sealevel 11

Majorclimatedrivers 12

Extremeevents 14

Tropicalcyclones 14

Heavyprecipitationandflooding 15

Droughts 16

Heatwavesandwildfires 16

Marineheatwaves 17

Otherextremeevents 18

Climate-relatedimpactsandrisks 20

Mortalityandaffectedpopulation 20

StatusofearlywarningsystemsinAsia 21

EarlywarningandanticipatoryactioninAsia 22

Challengesandopportunities 23

Datasetsandmethods 25

Listofcontributors 28

Endnotes 29

Weneedyourfeedback

Thisyear,theWMOteamhaslaunchedaprocesstogatherfeedbackontheStateoftheClimatereportsandareasforimprovement.Onceyouhavefinishedreadingthepublication,weaskthatyoukindlygiveusyourfeedbackbyrespondingto

thisshortsurvey

.Yourinputishighlyappreciated.

Keymessages

In2023,themeantemperatureoverAsiawas0.91°Cabovethe1991–2020referenceperiod,thesecondhighestonrecord.

Manypartsoftheregionexperiencedextremeheateventsin2023.Japanexperienceditshottestsummeronrecord.

GlaciersinHigh-MountainAsiahavelostsignificantmassoverthepast40years,atanacceleratingrate.In2023,record-breakinghightemperaturesanddrierconditionsintheEasternHimalayasandtheTienShan(mountainrange)exacerbatedmassloss.

TheoceanaroundAsiahasshownanoverallwarmingtrendsincetimeseriesbeganin1982.In2023,sea-surfacetemperatureanomaliesinthenorth-westPacificOceanwerethehighestonrecord.

South-westChinasufferedfromadrought,withbelow-normalprecipitationlevelsnearlyeverymonthof2023.EssentialwinterprecipitationwasalsobelownormalintheHinduKushregion,andtherainsassociatedwiththeIndiansummermonsoonwereinsufficient.

In2023,over80%ofreportedhydromete-orologicalhazardsinAsiawerefloodandstormevents.Yemensufferedheavyrainfallandresultingwidespreadfloods,withover30reportedcasualtiesandover165000in-dividualsaffectedinover70districts.

Overall,the79reportedhydrometeoro-logicalhazardeventsin2023ledtoover2000fatalitiesandimpactedmorethan9millionpeople.

Approximately80%ofWMOMembersintheregionprovideclimateservicestosupportdisasterriskreductionactivities.However,thereisagapinclimateprojectionsandtailoredproducts(providedbylessthan50%ofMembersinWMORegionalAssociationII(Asia))thatareneededtoinformriskmanagementandadaptationtoandmitigationofclimatechangeanditsimpacts.

iii

Foreword

Weareatacriticaljuncture,wheretheimpactofclimatechangeintersectswithsocietalinequalities.Itisimperativethatouractionsandstrategiesmirrortheurgencyofthesetimes.Reducinggreenhousegasemissionsandadaptingtotheevolvingclimateisnotmerelyanoption,butafundamentalnecessity.

WMOiscommittedtoprovidingscienceandservicesthathelpbridgedisparitiesandaddressdevelopmentalgaps.AsSecretary-General,IamdedicatedtoprioritizingregionalinitiativesandensuringthatinnovativesolutionsreacheveryMember,particularlythosefacinggreaterdevel-opmentalchallenges.ThepresentreportonthestateoftheclimateinAsiais,inthiscontext,atooltoinformdecision-makingattheregionallevel.

Acomprehensiveanalysisoftheclimatelandscapeformsthecornerstoneofinformeddecision-makingandresponsestrategies.Thisreport,thefourthofitskind,shedslightontheoccurrenceofextremeweathereventsandmonitorskeyclimateindicatorsinAsia.Itcontextualizesthesefindingswithinbroaderclimatetrends.Thereport'sconclusionsaresobering.Manycountriesintheregionexperiencedtheirhottestyearonrecordin2023,alongwithabarrageofextremeconditions,fromdroughtsandheatwavestofloodsandstorms.Climatechangeexacerbatedthefrequencyandseverityofsuchevents,profoundlyimpactingsocieties,economiesand,mostimportantly,humanlives.

WMOremainssteadfastinitscommitmenttomonitoringtheclimatesystemandprovidingauthoritativeinformationtoleadersandthepublicalike.ThroughrobustcollaborationacrosstheUnitedNationsfamilyandwithpartners,weareempoweredtodeliverimpactfulservicesgroundedinreliableinformation.TheGlobalFrameworkforClimateServices,andtheEarlyWarningsforAllinitiative,standastestamentstotheeffectivenessofsuchcollaborativeefforts.Ourpledgeextendstoreachingeverycorneroftheglobe,ensuringthatnoMemberorindividualisleftbehind.

Thespiritofcollaborationandpartnershiphasbeeninstrumentalinthecreationofreportssuchasthisone.IextendmysinceregratitudetoourMembers,sisterUnitedNationsagencies,andalltheexpertsfromboththeAsianregionandaroundtheworldfortheirinvaluablecontributionstothescientificcoordinationandauthorshipofthisreport.

(Prof.CelesteSaulo)Secretary-General

iv

Preface

AsiaandthePacificremainedthemostdisas-ter-impactedregionin2023.Floodsandstormscontinuedtocausemostdisaster-relateddeathsandeconomiccosts,astheyaffectthelargestnumberofpeople.Atthesametime,theimpactofanincreasingnumberofheatwaveswasalsomoresevere.

Yetagain,in2023,vulnerablecountriesweredis-proportionatelyimpacted.Forexample,TropicalCycloneMocha,thestrongestcycloneintheBayofBengalinthelastdecade,hitBangladeshandMyanmar.Earlywarningandbetterprepared-nesssavedthousandsoflives.Inthisregard,itisimportanttorecognizethekeycontributionthatregionalcooperationmadethroughtheWMO/

ESCAPPanelonTropicalCyclones(PTC)inwarningandforecastingwithhighaccuracyandleadtime.Thisunderscorestheimportanceofregionalapproachesforearlywarningoftransboundaryhazards.

Acriticalgapintheearlywarninginformationchainliesinknowledgeandunderstandingofdisasterrisk.Addressingthisgapisfundamentalforeffectivemulti-hazardearlywarningsystemsandthereforeisakeydeterminantoftheimplementationoftheGlobalExecutiveActionPlanonEarlyWarningsforAllinAsiaandthePacific.

TheEconomicandSocialCommissionforAsiaandthePacific,ESCAP,hasrespondedtothisneedbyconfiguringtheRiskandResiliencePortaltodeepentheknowledgeofrisk,especiallyinhotspotswhereriskisintensifyingundervariouswarmingscenarios.The2023editionoftheESCAPAsia-PacificDisasterReportflaggedthatthereisanarrowwindowforAsiaandthePacifictoincreaseitsresilienceandprotectitshard-wondevelopmentgainsfromthesocioeconomicimpactsofclimatechange.

Inthiscontext,theStateoftheClimateinAsia2023isanefforttobridgegapsbetweenclimatescienceanddisasterriskthroughevidence-basedpolicyproposals.ESCAPandWMO,workinginpartnership,willcontinuetoinvestinraisingclimateambitionandacceleratingtheimplementationofsoundpolicy,includingbringingearlywarningstoallintheregionsothatnooneisleftbehindasourclimatechangecrisiscontinuestoevolve.

(ArmidaSalsiahAlisjahbana)

Under-Secretary-GeneraloftheUnited

NationsandExecutiveSecretaryofESCAP

1

Globalclimatecontext

Theglobalannualmeannear-surfacetemperaturein2023was1.45±0.12°Cabovethe1850–1900pre-industrialaverage.Theyear2023wasthewarmestyearonrecordaccordingtosix

globallyaverageddatasets.1

Thenineyears2015to2023weretheninewarmestyearsonrecordinalldatasets.

2

Atmosphericconcentrationsofthethreemajorgreenhousegasesreachednewrecord-observedhighsin2022,thelatestyearforwhichconsolidatedglobalfiguresareavailable,withlevelsofcarbondioxide(CO2)at417.9±0.2partspermillion(ppm),methane(CH4)at1923±2partsperbillion(ppb)andnitrousoxide(N2O)at335.8±0.1ppb,respectively150%,264%and124%ofpre-industrial(before1750)levels(Figure1).Real-timedatafromspecificlocations,includingMaunaLoa

3

(Hawaii,UnitedStatesofAmerica)andKennaook/CapeGrim

4

(Tasmania,Australia)indicatethatlevelsofCO2,CH4andN2Ocontinuedtoincreasein2023.

Overthepasttwodecades,theoceanwarmingratehasincreased;theoceanheatcontentin2023wasthehighestonrecord.Oceanwarmingandacceleratedlossoficemassfromtheicesheetscontributedtotheriseoftheglobalmeansealevelby4.77mmperyearbetween2014and2023,reachinganewrecordhighin2023.Between1960and2021,theoceanabsorbedabout25%ofannualanthropogenicCO2emittedintotheatmosphere,

5

andCO2reactswithseawaterandlowersitspH.Thelimitednumberoflong-termobservationsintheopenoceanhaveshownadeclineinpH,withareductionoftheaverageglobalsurfaceoceanpHof0.017–0.027pHunitsperdecadesincethelate1980s.

6

Thisprocess,knownas

oceanacidification,affectsmanyorganismsandecosystemservices7

andthreatensfoodsecuritybyendangeringfisheriesandaquaculture.

ppm

ppb

ppb

(a)Carbondioxideconcentration(b)Methaneconcentration(c)Nitrousoxideconcentration

340

420

1950

1900

330

400

1850

320

380

1800

1750

310

360

1700

300

340

1650

199020002010202019902000201020201990200020102020

(d)Carbondioxidegrowthrate(e)Methanegrowthrate(f)Nitrousoxidegrowthrate

ppm/year

4

3

2

1

0

1990200020102020

ppb/year

20

15

10

5

0

–5

1990200020102020

ppb/year

1.5

1.0

0.5

0.0

1990200020102020

Figure1.Toprow:Monthlygloballyaveragedmolefraction(measureofatmosphericconcentration),

from1984to2022,of(a)CO2inpartspermillion,(b)CH4inpartsperbillionand(c)N2Oinpartsperbillion.

Bottomrow:thegrowthratesrepresentingincreasesinsuccessiveannualmeansofmolefractionsfor

(d)CO2inpartspermillionperyear,(e)CH4inpartsperbillionperyearand(f)N2Oinpartsperbillionperyear.

2

Regionalclimate

ThefollowingsectionsanalysekeyindicatorsofthestateoftheclimateinAsiaduring2023.Onesuchindicatorthatisparticularlyimportant,temperature,isdescribedintermsofanomalies,ordeparturesfromareferenceperiod.Forglobalmeantemperature,theSixthAssessmentReport(AR6)oftheIntergovernmentalPanelonClimateChange(IPCC)

8

usesthereferenceperiod1850–1900forcalculatinganomaliesinrelationtopre-industriallevels.However,thispre-industrialreferenceperiodcannotbeusedinallregionsasabaselineforcalculatingregionalanomaliesduetoinsufficientdataforcalculatingregion-specificaveragespriorto1900.Instead,the1991–2020climatologicalstandardnormalisusedforcomputinganomaliesintemperatureandotherindicators.RegionaltemperatureanomaliescanalsobeexpressedrelativetotheWMOreferenceperiodforclimatechangeassessment1961–1990.Inthepresentreport,exceptionstotheuseofthesebaselineperiodsforthecalculationofanomalies,wheretheyoccur,areexplicitlynoted.

TEMPERATURE

Variationsinsurfacetemperatureandprecipitationhavealargeimpactonnaturalsystemsandonhumanbeings.ThemeantemperatureoverAsia

9

in2023wasthesecondhighestonrecord(Figure2),0.91°C[0.84°C–0.96°C]abovethe1991–2020averageand1.87°C[1.81°C–1.92°C]abovethe1961–1990average.ParticularlyaboveaveragetemperatureswererecordedfromwesternSiberiatocentralAsiaandfromeasternChinatoJapan.JapanandKazakhstaneachhadrecordwarmyears.

°C

1.0

0.5

0.0

–0.5

–1.0

–1.5

–2.0

HadCR

NOAAG

UT5(1900–2023

lobalTemp(19

)

00–2023)

GISTEM

Berkele

P(1900–2023)

yEarth(1900–2

023)

JRA-55

ERA5(

(1958–2023)

1979–2023)

1900192019401960198020002020

Year

Figure2.Annualmeantemperatureanomalies(°C),1900–2023,averagedoverAsia,relativetothe1991–2020average,forthesixglobaltemperaturedatasetsindicatedinthelegend.

Source:HadCRUT5,BerkeleyEarth,NOAAGlobalTempandGISTEMParebasedoninsituobservations.ERA-5andJRA-55arereanalysisdatasets.Fordetailsonthedatasetsandtheplotting,see

Temperaturedata

.

3

Figure3.Meannear-

surfacetemperature

anomalies(°C,differencefromthe1991–2020

average)for2023.Dataarethemedianofsixdatasetsasindicatedinthelegend.See

Datasetsandmethods

fordetails.

Figure4.Trendsinmean

surfaceairtemperature

forthesixWMOregionsand

theglobalmean(°C)over

foursub-periodsusingthesixdatasets.Thecolouredbars

indicatethetrendinthemeanofthedatasets.Theblack

verticallinesindicatetherangebetweenthelargestandthe

smallesttrendsintheindividualdatasets.

AveragetemperatureswerebelownormalinpartsoftheinlandIndianPeninsula(Figure3).

Overthelongterm,aclearwarmingtrendhasemergedinAsiainthelatterhalfofthetwentiethcentury(Figures2and4).Inthetworecentsub-periods(1961–1990and1991–2023),Asia,thecontinentwiththelargestlandmassextendingtotheArctic,haswarmedfasterthanthegloballandandoceanaverage.Thisindirectlyreflectsthefactthatthetemperatureincreaseoverlandislargerthanthetemperatureincreaseovertheocean,asstatedintheIPCCAR6report.ThewarmingtrendinAsiain1991–2023wasalmostdoublethewarmingtrendduringthe1961–1990period,andmuchlargerthanthetrendsoftheprevious30-yearperiods(Figure4).

–5.0–3.0–2.0–1.0–0.5–0.2500.250.51.02.03.05.0°C

Trend(°C/decade)

0.6

0.4

0.2

0.0

–0.2

Africa

Asia

SouthAmerica

NorthAmerica

South-WestPaci?c

Europe

Globe(landandocean)

Trends

1901—1930

Trends

1931—1960

Trends

1961—1990

Trends

1991—2023

4

PRECIPITATION

Precipitationisakeyclimateparameter,essentialforsocietyintermsofprovidingwaterfordrinkinganddomesticpurposes,agriculture,industryandhydropower.Variationsinprecipitationalsodrivemajorclimateeventssuchasdroughtsandfloods.In2023,substantialprecipitationdeficitsintheregionwereobservedintheTuranLowland(Turkmenistan,Uzbekistan,Kazakhstan);theHinduKush(Afghanistan,Pakistan);theHimalayas;aroundtheGangesandlowercourseoftheBrahmaputraRivers(IndiaandBangladesh);theArakanMountains(Myanmar);andthelowercourseoftheMekongRiver(Figure5and6).Otherregionswhichhadbelow-normalprecipitationweretheregionbetweentheTianShanandGobiAltai(ChinaandMongolia);theWesternSiberianPlain;theStanovoyRange;theArcticCoastbetweentheTaymyrPeninsulaandtheNewSiberianIslands(RussianFederation);aswellasJapanandthesouth-westernpartofChina.

ThelargestabsoluteprecipitationexcesseswereobservedaroundthelowercourseoftheIndusRiver(Pakistan),theTenasserimRange(Myanmar),inKamchatkaandtheKolymaRange(RussianFederation).Unusuallyhighprecipitationtotals(Figure6)werealsonotedinManchuriaandtheNorthernChinaPlain(China);betweentheYamalandTaymyrPeninsulas(RussianFederation);theKazakhSteppe(Kazakhstan);andtheArabianPeninsula(SaudiArabia).

Figure5.Precipitationanomaliesfor2023,expressedasapercentageofthe1991–2020average

Source:GlobalPrecipitationClimatologyCentre(GPCC),

DeutscherWetterdienst,Germany

0100200300400500%

Figure6.Totalprecipitationin

2023,expressedasaquantileofthe1991–2020referenceperiod,forareasthatwouldhavebeen

inthedriest20%(brown)and

wettest20%(green)ofyears

duringthereferenceperiod,withdarkershadesofbrownandgreenindicatingthedriestandwettest10%,respectively

Source:GPCC,DeutscherWetterdienst,Germany

0.00.20.40.60.81.0Quantile

5

Cumulativemassbalance(mw.e.)

LeviyAktruGlacier,Altay

Ts.TuyuksuyskiyGlacier,westernTienshan

UrumqiGlacierNo.1,easternTienshan

XiaoDongkemadiGlacier,TanggulaShan,innerTibetanPlateau

Averageofglobalreferenceglaciers

CRYOSPHERE

ARCTICSEAICE

Sea-iceextentisakeyindicatorofclimatevariabilityandclimatechangeinthepolarregions.Seaicestronglymodulatessurfaceoceanwavesandtheair-seaexchangesofheat,momentum,moisture,andsoforth,therebyinfluencingtheregionalclimateandtheglobalclimate.Accordingtotheconsensusstatementofthe11thand12thsessionsoftheArctic

ClimateForum,10,11

themaximumArcticiceextentinwinter2023wasreachedon6March2023.Thevalueof14.6millionkm2wasthe5thlowestinthe45-yearsatelliterecord.NegativeiceanomaliesweremostnotableintheWesternandEasternNordicregions.AsmalleranomalywasnotedintheChukchiandBeringRegion.TheminimumArcticiceextentinsummer2023(approximately4.4millionkm2)occurredon17Septemberandwastheeighthlowestannualminimumdailyextentonrecordsince1979(itshouldbenotedthatnumbersandrankingsmayvarymarginallyacrossdifferentdatasetsduetoslightlydifferentcalculationmethodsandthresholds).SignificantnegativeanomaliesweremostprominentintheareasoftheEurasianandCanadianArctic,thoughsomeresidualseaiceremainedinboththeNorthernSeaRouteandthenorthernrouteoftheNorthwestPassageshippinglanesuntilthetimeoffreeze-up

.12

GLACIERS

Glaciericemassissensitivetochangesinregionaltemperature,precipitation,andsurfaceradiation.Themeltingofglaciersaffectssealevel,regionalwatercyclesandtheoccurrencesoflocalhazardssuchasglacierlakeoutburstfloods(GLOF).TheHigh-MountainAsia(HMA)regionisthehigh-elevationareacentredontheTibetanPlateau;itcontainsthelargestvolumeoficeoutsideofthepolarregions,withglacierscoveringanareaofapproximately100000km2.Overthelastseveraldecades,mostoftheseglaciershavebeenretreating,withthealtitudesoftheequilibriumlines(thelowertopographiclimitoftheglaciers)gradually

rising.13,14

Inthepast40years,fourglaciersintheHMAregionwithmorethan30yearsofongoingmass-balancemeasurements(Figure7)haverecordedsignificantmasslosses,withanincreaseintherateofmasslosssincethemid-1990s.Atthesametime,thesefourglaciersshowanoverallweakercumulativemasslossthantheaveragefortheglobalreferenceglaciers(indicatedbyagreylineinFigure7)duringtheperiod1980–2023.AccordingtotheTechnical

0

–5

–10

–15

–20

–25

19801990200020102020

Year

Figure7.Cumulativemassbalance(inmetreswaterequivalent(mw.e.))offourreferenceglaciers

intheHighMountainAsiaregionandtheaveragemassbalanceoftheglobalreferenceglaciers

Source:Dataregardingtheglobalreference

glaciers(grey),LeviyAktruGlacier(green),

Ts.TuyuksuyskiyGlacier(orange)andUrumqiGlacierNo.1(blue)arefromthe

WorldGlacierMonitoring

Service(WGMS)

(seealsoWGMS.GlobalGlacier

ChangeBulletinNo.5(2020–2021);Zemp,M.;

G?rtner-Roer,I.;Nussbaumer,S.U.etal.,Eds.;

ISC(WDS)/IUGG(IACS)/UNEP/UNESCO/WMO,WGMS:Zurich,Switzerland,2023).DataregardingtheXiao

DongkemadiGlacier(purple)arefromthe

Chinese

AcademyofSciences(CAS)

.

6

Latitude

50°N

40°N

30°N

100°E

LeviyAktru

–737

MuzTaw

GlacierNo.599

Turgen-Aksuu–868Ts.Tuyuksuyskiy

BarkrakSredniy–855–488

–809GolubinB–Karabatkak

–1412Sary-Tor–930

–1510

Abramov

GlacierNo.457

–482

XiaoDongkemadi

+230

0~110

Pokalde

–2350

–1139

ChangriNupWest

–2650

–500~0

–1000~–500

–1500~–1000

–2000~–1500

UrumqiGlacierNo.1

–1291

–2650~–2000Glacier(RGIv7.0)

Massbalance(mmw.e.)

DurungDrung

–380

ChhotaShigri

+110

BaishuiRiverGlacierNo.1

Laohugou

–853

Yala

–1297

–1075

–539

40°N

30°N

50°N

70°E

80°E

90°E

80°E

90°E

70°E

100°E

Longitude

Figure8.Preliminaryestimationsofthe2022–2023massbalanceofglaciersintheHighMountainAsiaregion.Theareaindicatedbygreycontoursis2500metresabovesealevel.

Source:WMOThirdPoleRegionalClimateCentreNetwork(TPRCC-Network)andWGMS;theoriginalobservationsuponwhichthisfigureisbasedarefromChina,India,Kazakhstan,Kyrgyzstan,Nepal,theRussianFederation,TajikistanandUzbekistan.

SummaryoftheWorkingGroupIcontributiontoIPCCAR6,glaciersoverSouthAsiahavethinned,retreated,andlostmasssincethe1970s(highconfidence),althoughpartialKarakoramglaciershaveeitherslightlygainedmassorareinanapproximatelybalancedstate(mediumconfidence).

Fortheglaciologicalyear2022/2023,20outof22glaciersobservedintheHMAregionshowcontinuednegativemasschanges.Record-breakinghightemperatureanddryconditionsintheEastHimalayaandmostoftheTienShanexacerbatedmasslossformostglaciers.Duringtheperiod2022–2023,UrumqiGlacierNo.1,inEasternTienShan,recordeditssecondmostnegativemassbalance(1.29mw.e.)sincemeasurementsbeganin1959(Figure8).

PERMAFROST

Permafrostissoilthatcontinuouslyremainsbelow0°Cfortwoormoreyearsandisadis-tinctivefeatureofhigh-latitudeandhigh-altitudeenvironments.Itischaracterisedbytwokeyvariables,observedtomonitorpermafrostlong-termchangesthatweredefinedasproductsoftheEssentialClimateVariables(ECVs)oftheGlobalClimateObservingSystem(GCOS):meanannualpermafrosttemperatureandthicknessoftheuppermostlayerofseasonallythawing

7

soil—definedasactivelayerthickness(ALT).MonitoringcarriedoutbytheRussianFederalServiceforHydrometeorologyandEnvironmentalMonitoring(RosHydroMet)indicatesthatalmostthroughouttheentireterritoryofthepermafrostzoneoftheRussianFederationin2023,positivetrendsintheALTthicknessremained,closeinvaluetothetrendsseeninthe

1976–2022period,whichindicatesthepersistenceofastabletrendofincreasingtheALT.15

ThemostrapidthawingofpermafrostisintheEuropeannorth,thePolarUrals,andthewesternregionsofWesternSiberia.RelativelymoderateandweakratesofpermafrostthawingareobservedinthecoastalregionsofCentralandNorth-EastSiberia(Figure9).

ThetrendofincreasingALTintheRussianFederationpermafrostzoneisdue,firstofall,tothecontinuingincreaseinairtemperaturesinthehighlatitudesoftheArctic.Intermsofairtemperature,2023wasthesixthwarmestyearintheArcticsince1900.IPCCAR6estimatesthatthawingterrestrialpermafrostwillleadtocarbonrelease(highconfidence),thoughthereislowconfidenceinthetimingandmagnitude.Furthermore,thereportpointsoutthatpermafrostthawing,aswellasglaciermeltandsnowdecline,arealreadyimpactingpopulationsaswellasirrigation,hydropower,watersupply,culturalandotherdomainsdependingonice,snowandpermafrost.

Permafrost

Continuous

Discontinuous

Isolated

CoeicientoflineartrendofALT(cm/10years)<00–56–1011–15>15

Figure9.Long-termtrendofthethicknessoftheuppermostlayerofseasonallythawingsoil(ALTincmper10years)fortheperiod1976–2023.Permafrostisclassifiedbycoverageincontinuous(90%ofthelandscape),discontinuous(50–90%),andsporadic

(10–50%)zonesandisolatedpatches(10%),dependingontheareacontinuity.

Source:Measurementsfromobservationsites(sitecodesareindicatednexttocirclesonthemap),RussianFederalServicefor

Hydrometeorology(Roshydromet)withinthe

CircumpolarActiveLayerMonitoringProgram

.SeeAnisimov,O.A.;Lavrov,S.A.;

Zhirkov,A.F.etal.PermafrostDataAssimilationandReanalysis:ComputationalSetupandModelValidationforNorthernEuropeanRussiaandEasternSiberia.RussianMeteorologyandHydrology2020,45,269–275.

/10.3103/S106837392004007X

.

SeealsoAnisimov,O.A.PotentialFeedbackofThawingPermafrosttotheGlobalClimateSystemthroughMethaneEmission.EnvironmentalResearchLetters2007,2,91–98.

/10.1088/1748-9326/2/4/045016

.

8

SNOWCOVER

Snowcoverplaysanimportantroleinthefeedbackmechanismsintheclimatesystem(such

asalbedo,16

run-off,soilmoistureandvegetation).He