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PROGRESS ARTICLE PUB Ll SHED ONLlNE 21 APRIL 2013 1001 10 10 :lS/NGE01797 Continental-sea le temperature variability during the past two millennia PAGES 2k Consortium* Past global climate changes had strong regional expression. Toelucidate their spatio-temporal pattern, we reconstructed past temperatures far seven continental-scale regions during the past one to two minennia. The most coherent fea\ure in nearly all of the regional temperature reconstructions is a long-term coolingtrend, which ended late in the nineteenth century. At multidecadal to centennial scales, temperature variability shows distinctly different regional patterns, with more similarity within each hemisphere than between them. There were no globally synchronous multi-decadal warm or cold intervals that define a worldwide Medieval Warm Period or Little Ice Age, but all reconsbuctions show generally cold conditions between AD1580and 1880, punctuated in sorne regions by warm decades during the eighteenth century. The bansition to these colder conditions occurred earlier in the Arctic, Europe and Asia than in North America or the Southern Hemisphere regions. Recent warming reversed the Iong-term cooling; during the period AD1971-2000, the area-weighted average reconsbuded temperature was higher than any other time in nearly 1,400 years. llfing Ihecurrenl inlerglocial perio,l EarI lis d imale has llndergone signifl.-:anl dinwle vari~ ionslh~ haw pJ lo be (p.wnl iflell ~ lile conli nenlal scale, where dim~e variabilily is argt~lbly more rdev,lnl lo u::osys!ems ,md socidies Ihan globally avemgt:'I.1 condil ions. Ddermining lile magnilllde oflhese chang..~ is needed lo disl inguish anl hrq)ogt:llk impacls f mm I he ba::kground ran~ of nalural varht)il iI y'. I~onsl rucl ing !Val iolemporal pallerns of pa;;l dinwle variabil iI y hdps us lo lUl,~rsland and (p.wnl ify I he in1llelKe of e;"1ernally forcE'l.I and irt rinsk ,~' namics of I he global d im~e srs100m'. and lo lUldersland n~llfal dim~e varbhilily, whkh rre,islo be Cl)nsi,~red in fulure dinwle scenarios~'. Here I'~ presenl a global d~ a se!. of proxy ft:yord" and assocbled lenf'E'r~ llre ft'Consl nel iOI"t> for seven conl inertal -scale ft1:ions. \Ve ,~scrihe Ihe mosl pmminenl fealllres ofconl inenl a1 -scale len-per~urechangt.~ al nlldl i· da::adall o millennial limescaJes.ln conlrasl lo other ft'("('nl global-seaJe nxonslruelions'.o, Ihis SIU,~' prO\idt,~ an inler-conlinenlal peP.'f""l.::liw of lemperalllre en)]ul ion dllfing I hepasl one lo Iwo Ihousand }~ars. D lhe PAGES 2k Network and temperature reconstructions ·Ihe ·1k Network' oflhe IGHP Pasl Global amlf,~s (PAGES) projecl aims lo pro,ilCe ,1 global array of rt."gional climale l"t'Conslrteliort> for Ihe pasl 1000 }~ars ( \\"I,w.paf,,,,,~- ig bp. org/\\"()rkinggn lt~ "¡1k- rl:1 \\"orkl. Nine PAGES 1k \\"orking grot~s I"tVrese1ll eiglll conli nertal scale rt.'gions (Hg. 1) and lile oceans. Rt1lional rtvreselll~ ion brings cril ical experl knowJed~ ofindivi,ilal proxy dala se!.s, whieh isessenljal for imprll\ing palaeocJimale l"t'Conslrtelions'. ·llle PAGES 1k Network is coor,linaled wil h lile N,lI ional Oceanic and Almospheric Adminis!ral ion (NOAA) \Vorld Dala Cenler for Paleod im~ ology lo e;;tahlish a henchmark d~ abase of proxy dim~e ft'Cords for Ihe pa;;l I wo millennb (Supplemertary Nole Al. Rt'Consl rtel ion domaill'i for Ihe PAGES 1k I"t~gioll'i I"tvorled l-ere encompass 36% of lile Eartlú surfac.e (Fig. Il. Ah hOllgh Ihe ft.'gioll'i lar~y coi ncide wilh Ihe cortinenl s r~ller Ihan climalological crileria. lile anrl.lal mean lenf'E'r~ure averaf,~d over Ihese I"t'gions explains 90% ofllle glol)a1 nlean annllallemperalure variabil iI y in lile insl rtunenlal l"t'Cord (St. n"ll emt.lllary Fig. SI ). Suil able pro;,,)' ",,:or&; fmm !\frica (St.4-p emenlary Parl 11) are currenlly hlt) spar9o' for a rt~ d.:>! e lemperalure synlllesis', and analysis of palaeoct':.lnogrl-lhic dala by Ihe m.:elllly forllltxl Ocean1k grOl~) is in progress". E¡¡eh rt1:ional grot4-) idenl ified I he pro;..)' d inwle l"t'Cords I h~ Ihey 1lltlnd Wt--re hes! suilE'l.I for l"t'Consl rtel ing anlll~ll or warlll-season lelllperaIllre vanabilil y I,il hin Illeir rq¡ion, lL'iing (/ priori e~ al"llislled crileria (St. ~pl emenlary Dalabase SI l. "1 he PAGES 2k ,bla SIc"'1. indlll.b 511 lime series of I I"t"'e rings, pollen, corals. lake and manne sedimerts. glocier ice, spdeolhent> and hisl orical dOCtllllenlsl h~ rtl.::ord(han~s in biological or pllysieal processes Ihal can be llsed lo rtYOn;;lnlCl IeJllptTalllre \~lrial ions. F..XCEpl for Norlh America, IllO' PAGES 2k l"t'ConslrtlClions haw anlll~1.l resol l. ion (St n"llelllelllary Fig. S1 a nd lJal,~)ase 52). lhft"'e of 11'le len~)('nllure I"tyonsl rtel ions span ~)proxinwldy 1,000 }~ars (Arclie, Fl.lro.:ve and Anlan::lical, ,md Ihft:-e cowr Ihe pasl 1,000UOO }~ars (Asia, Stltllh America an..! AlNralasia). "Ihe Norlh American rt--gion inclu,~s a ;;horter decadally rt~\'txllrt"'e-ring baStxl m.::onsl rtlClion (bock lo AD 11(0) and a longer 3O- }~ar- ft:~olvtxl pollen - baSt~d l"t'Consl rtlCl ion (bock lo AD 360). Each conlinenlal -scale lemper~llre rtYOn;;lrtlClion \,~\S ,~rivtxl using difkmll sI~ isl ical metho&', wil h each 1k Nt."'1. work grot4-) lailoring ils pJl.)("t~dllf\;~ lo Ihe si renf,~ 11'> of I hd r rt.1,>ional pro;..)' rtyords ,md calibmlion la~"'1.s (St ~)pleJlJenlary Parl 11). Mo;;t gnJt~s llsed eilher a seal ing appro,leh I o adju;;l Ihe nlt'"J n ¡lIld va n'lile.e of a prt~,Iic lor composile lo an ill."'i nlllJelll al lar~"'1., or .1 rt--gression -based Iffhnkp.telO (')0.1 rael acommon signal f mm I hepft~diclOrs tL'iing principal COlllpol'lenls or dis!alKe wdgh ing ("1¡11"lle Il . SonJe of lile Ilctero~ neil ies among Ihe ft.--gionalleJllperalure l"t'Colls1 rtt:1 iOI"t> miglll be lile lo di1lt:--ren:.es in l"t'Consl rtl::1 ion nltl ho..!s. Idlich may tUldere~ im~e I he anlllilllde oflow- frt"ql~IK}' variabilily dil¡Telllly1O. Furl hermore, di1lt:--reIK"'-"'S het I''l"'en regional I"tYlHN nlCl ions nwy relh:1 difkmKes in Iheir l"t'Consl rtlCl ion larf,\:1s (·bnd only" versus ·l,md ark.1 oc.eari), proxy I ypes and pro;,,)'- d~ ing uncerl ailll it~. "Ien-penllllre vari<i)il iI y a1so di1lt:Ts betwt"'eJl SlllllllJer and 'llHl.lal rtXonslnlClions. a1lhough Ihe Iwo are conl'"laled in meteorolof,>ical rt'Cord" from our rt1:ions (n le,lIl r-vallle = 0.73 ± UOS: Tal"lle Il. Scft:"'elling proxy l"t'Cords based on Illeir ;;I~islical simiJarily lo an in;;lrtUllertallal1""1, as was done for mos! I"t'gioll..ll I"tyonsl rtelioll.~, can hanver inlel})fti~ ions I h.al inn~w con ~)aring I he variabilily of lempewlllre dllfing Ihe I I,~nl ieth celllllfy lo Ihal of earlier perio..!s" . "liJ address Ihese iSSlleS, and lo ·A lullllsl 01 authors and their alllll atl ons app ears al lh e end 01 the paper NATURE GEOSCIENCE 1Va. 61 ,,-.AY 2013 1"''''','i.nii ure .(OO1! nii uregeoscience ~) 2013 Maar ill an Pub li sllers li rr it ed . AII rigllt s re",rv ed l39 PROG RESS ARTICLE NATURE GEOSCIENCE 001 WW"/NGEOP" Ollf analysis of nl.dli -decadal vari ab il it y focuses on 30-Y"' Jr-n\(\Ul le!llp"TalufeS (lhft'e calen.lu .h: a.~s) an d 1hdr s!.andardi7.ed val ues (Fig. 2: Supplemenlary DJlaba9i:' 52). lhis lemporal ft:~oIl. ion enabies lhe indu"ion of 1he JO-year- resol \Td pol lt:.,l-based ft'Cons1 fl l~ lio n from North Amerk,l. Using s!.andard iztxl Val lle> cin:ulll wrJl s rt.1lional diflt.~rt.lKes in lhe magnitude of lemper~ llrt.' variabilily. which '~"pen ds on b""' ogml¡)lkal faclors an..! c an be i n lll ~IKe..! by seaso nal bia9i:'s in some proxies. A rct ic Mil lennial cooling ' Doc ument esy ' Glac ier ice ' COf als Inst rum ent al ' ' ' P" len Mar ine ", dimen! , ' ' T,." rings Sp<> leoth ems Fig ure ll The PAGE S 2k Network. Boxes ShON the coo tlnent a -sca e regioos u sed In t hls stu Jy The p ie chart s r ep resen! th e trac tloo 01 proxy data types used jor eac h regiooa reco nstructloo. Supp ementary Database Sl lncludes Int or matloo abo ut each study slte and the proxy data lor all time senes used In th e reg iona l recoos tructloos aS9;;;ss ll"l" exlenl \o which ¡he choice of ",Yon~rllclion metho..! mighl in1l lellCe our concJ usillJlS, \\\: also npplied u nifu rm proce'.lfeS lo 11"l" same pro:\.) ' d,. a lo ~nerale lh",,,, ¡lddiliunaJ ro::.onslruclions from each "'1lion (Sl4-"lp1eme!llary Note B): .Ilee are referrt~d 10 as "ahernaI in" rt:yonsl. nlel ions', On: r lheir rt.~)t:'Cl iw nxor..! lenglhs, all ft'gions experimce..! a longler m cool ing lren..! fol lo\\"~:..! by rt.'Cenl wa rm ing ..!uring l l-e l\\"enlie1.h cenlury, excepl Anlan:lka. Befort.' Al) 190) (Stn ¡)emenlary lal">le 52 ilKlllI.1es an analysis of rt.'gressions up 10 bl~ h Al) 1900 an..! 1850), 1he ro ol ing 1ren ..! is signiflclIll (P < 0.05: sre Mct ho.ls for s!. alis!. icall e~ s) in all ft..'gions excepl Norlh America. where l he cool ing 1ren ..! is \\"eakly signiflc anl (P < 0. 10) in lhe 1rt.' e-ring m:ons1 fllCl io n. an ..! nol signiflcanl in 1he p ol lm rt.'Cons!. fl lClion. l he regional r~ e of cool ing varies be1. \\"l'en alXll . 0. 1 an ..! 0.3 oC pe r 1,000 years. 5i nce AD looo - l heirJl erval rt.v rt.~nle..! i n all rt."'gions - lhelrt."h b:are also signiflcanl . excepl. for Etlro.ve ( P = 0. 13 ). 1n b~neral . l he o\Trall 1ren.b: in lhe JO- ye¡¡r- a\Tra~..! PAGE5 2k Ne1. work f('Cons!. fl lCl ions agrt.'e \\;1 h lhose in 1he all ernal i\'e nx ons!. fllCl ions ( St Jl~¡)emenlary la ble 52). 'I hey are al so consis!.ml wil h l he cool ing of gl ol,al sea~urbce lemperal urt.~ fro m }"t' Jrs AD I 10 [800 exhibiled in l he PAGF5 Oce¡¡n2k synl he sis". l he in.livi dml sile-le... d proxy ft'Cor..!s \\\:re also amt1YStXl lo .\e1ermine 1he exlenl 10 which l he long-ler m coo ling 1ren ..! is a COlllmon feJlure, an ~)p ro,lC h 1h ~ is in ,~·pen .~nl ofl he m::o n ~1 fllClion p roce..!urt.'s, Gerlf"r.llly. lhe lon~r lhe proxy rt.'Cord l he mort.' li kdy il is lo exhibil a signiflC arJl long-l"Tm cooling 1rt..,l..! (Fig. 3). For example, of Table 1 I Summary 01 continental -scale proxy temperature reconstrudions used in this study. Region (a r ea : 10" krn' ) A rc tlc (3 44 ) Tirn e p eri od Proxy ty p e ( nurnb er ) ( AO) 1- 2 0 00 Lake sedlln ents (22 ) Ice cores( 16) Tree r ing s (13) M arine sedlm en ts (6) A mlwl -s urnrn er r va lu e' Recon struct ion rn et h od ' Calib rati on r va luei Me an ifl nual Land & oc ean 0 .79 Pa iCo 056 Surnm er (JJA) 0 .6 6 Reconstru ct ion t arg et Maj or refer en ces 32 18 D oc um en L""y( l ) Spe leoth em (1) Eu rope (130) 1- 2003 A" 800 -198 9 Tree nng s (10 ) D oc um en t il"y( l ) Land on fy Tree nng s (22 9) Surnm er (JJA) eps 0.85 33 19 34 (3 11 ) 0 .71 PFR 0. 52 35 Me an ifl nu al Land and oc ean 0 .6 8 PCS R pe A 0.9 6· 056 · 36 37 Summ er ( DJF ) 0.8 2 PCRj CPS 0.8 2 38 0.80 pe R 0.80 39 0 .6 2 e ps 0.60 40 41 Land on fy Nor th Arn erica (125 ) 120 4 - 19 74 Sou th A m erica ( 200) 8 57-199 5 A ustra asia (37 9) 1001- 2001 Coral (13 ) Tree nng s (14) Spe leoth em (1) A ntarc tlca (3 44 ) 167- 200 5 Ice cores ( 11) 4 80-19 50 Tree nng s (146) Pu len (4 eco-regicm ) Tree r ing s (15) Instru m en t a s ( 4) Ice cores ( 2) M arine sedlm en t ( l ) Lake sedlm ent (1) Land onfy W arm seas on (S ept- Feb) Land and oc ean Me an ifl nu al Land on fy ' C o", ~ ti on b<t\"i" n ,n,m l JfXl >lJfTlfTl<f ( J un - A u ~ or D< c- r,b)t ' fTV fJ t m, b",d on H,dCftU T4. 1850- 20 12 ,rxj us ,""" I,rxj or I,rxj , rxj o", n " p< , t r.. ,.. coosl ru cti on t Jfg ' ts · c or , ~, t ion for Au, t fJ l ,,~ i, for t r.. WJ m ,."on (s.pt- r,b). 's., SlJpp~"",rt >ry Inf orrruti on· PJi Cq p, i,... , i,. co fTll J i, o,r f'C A, princip, l c~ rt 'n.l l·,~, · f'C ~ Princip, l ~ n.,lt ,.. co nsl ru el ion· f'CSR, princ ip Jl CO fTll "", rt, >¡l,ti Jl ,..g",~ on · C P~ C OfTll o ~ t , pt us >c, I'..,: f'P~ poi rt ·b,I· poi rt ' 'll ' ''~ '''' ~ , rxj P" lu"",,,, " laJ l, t <d for t h< cor,.. I, t ion b<tv,,,,, ,.. co nsl ru el,d. Ji u" ,rxj t Jfg~ insl ru "",rt, I dJl, U ~ fll t h< " IIbr, t io n p< , io ~ dorru ins ,rxj g' idd <d ",tru "" rt, 1prcxiJcls 'l"dfi ,d for ,xh "gion n t h< SlJ ppt"",rt,ry Infor""ti "" P...·' lu" for " Ibr, t ion , J ' , 11 <0.001",slffilt <d b,I prn" " lI1 domi" ti on Mort , ·C J lo "",t hods t hJt "ptm t h< ,. ,i, 1cor,~,t io n sl ru elurt of t h< ti "", ><fi" (,<l. 42). ' Cor" IJl ion for do,,"' 1"" , n """"tru el i"" Ilsq uJ ' , oo! of t h< '" ptJi,.,.d. J i,nc, (fi' ) of t h< fi of do"d.l l t ,.., ·,ifll·b,,.d " consl ru el ion to ,..gioru l poi ~ n · b,><d " cons! ru ct ion , (0.334) rrn lt ipt i,d b,I fe of t h< d,,,"' lt ,,,· ,n g· b,,.d " llb fJ ti on it ,. 1 (0.929 )· P.... , ~ , not d~"min<d ""on>, ,<O NATUREGEOSOENCE 1\.U 61 ,,-.AY 2013 1...........·. nJtu re.(OO1/ nJtu regi'OSC il'f1c. ~) 2013 Maar ill an Pub li sll e, s li rr it ed. AII ' igllt s , e", rve d NATURE GEOSCIENCE PROG RESS ARTICLE 001 WW"/NGEOP" ---+- V"ca nic-saar do",,,,t"rn s North -!CCCCéC-,______-,-C"""t-,,¡OL o :o Amer ¡ca ~ o - 1 .'... + Soo th + ii + § óOO _ _ Areli c Eur C9" "00 woo _ A"a _ 1400 _ _ Nc<th Amer ica - t rees Ne<th AmericJ - pJ len A ustr al", ;. ,eoo '"00 _ Sooth Amer ica _ A ntJrcti cd <-; '"00 "00 n ,g ,"O ,eoo V.es AD Fig ure 2 I Continenta l-sca le ternperature reconstruction s. 30-yea- -m ean temp eratur es ta- th e seve n PAG ES 2k Net\vor k regi oos , st andard iled lo have th e sa me meifl (O) ifld standard dev latlo n (1) <:Ne r th e per iod 01 CNe rlap amo ng records (A D119 0-1970) . Nor th Am er ica Includes a shorter tree-rlngbas ed and a loo ge r pu len-bas ed reco nstr uctloo . Das hed ootll n es enclos e Interva s 01 pronoonced v c>ca nlc and sU¿r- negatlve forc lng slnce AD 850 (see Meth ods ) Th e IONer pan el Sh ONS th e runn lng coo nt 01 numb er 01In dividual proxy records t>¡ r egio n. Data are li sted In 5upp em entary Databas e 52 lile 24 individual rtx.urds fmm all regiuns lhal exlend back lo Al) [, 10haw negal iw 5IqX'S be1.wem }\"ars Al) [and [900 (Süpplelllml ary Fig. 56), which is exl rt:me:!y unlikdy lu occur by chance (o ne-lailed sign le>l., P < 0.00 [l. Oflhese, llm:-e-(p.mr1ep.> oflhe slopes are sl ~ isl ically signiflCaral (P < 0.05). 01' lhe 90 rtl:.ord,; 1h,11 e¡.,1end 1o Al) [000, 54 haw rtql,11 iw slq)Cs (P < 0.03), owr one-lhird of which are sl ~ isl ically signiflcanl ( P < 0.05) . "[ 1)0' rt1lft.'Ssion analysis uf lhe cool ing lrend is ~t n)Or1 ed by lelllperalure dilkmKes al mtdli-ct.,11ennial scale;. lhe lhrt'e lon~~ rtl:.onsl rucl ions (An::l ir, EtIl'q)C ,md Anl arclica) 5IlOw highoT lemperalures during 11~ early ceral tll"ies ofll~ fll"sl millennitUll comp,lft'l.l wil h 1ho9i:" 01' lhe l~e (pre-l 1\\"111 iEl h) cenl11nt-'S of 11~ St'Cond miJlennilUll. eum mensur~ e cooling o(eurred ,.tring 1he lasl millennillm: for example, 1[~ flrst fUllr cenluries (,\1) [000- [400) \\"tTe 1\~lrmer lhan lhe following four cenluries (A l) [400- [SOO) in al[ rt~giorl~, ,bpilecuoling lhal slarts [xlwwn Al) [200 and [300 in lhe An::lic, F.uro!:)C and Asia. "[ he awnlf,'e lempenl1 ure ,lilkrelKe bt"'1.I\·tl"n 11~ fOllr-cenl11ry inlervals aWJ<lgt'l.l O\'tT alllhe ft.'gions was abot. O. [ oc. whirh isco nsi>l.enl wil h 1l")O'uIll~rlying millennial-scalecooling lrt.,ld (roughly - 0.1 °e ¡:¡er [,000 }\"'ll"s). Se\ual sludies haw inws1igaled lhe cmte of cooling be1.wtl"n 1[~lenlh and sixleelll h celll lll"ies, stlgf,'e>l.ing a polelll ial role 01' solar irradianre, \'oIcanir ael ivilY, land-cu\u chan~s and orl)iI aJly dnwn insolal ion"u-" . An en9i:"llIble uf sinlldal ions~)Crfornlt~d l-;lh acl inwle mode:! of iJlI enlledi~e cumplexi1y (St ~)plenJelll ary No1e e l 5IlOwS 1[k11 lhese fottr forci ngs a re lhe .10m ina 111 (¡USC 01' lhe a n Ill~ll mea n cool ing 1rend sinlldaled be1.\\"t't'll Al) 900 and [S5fl, l-;lh 1he rt'laliw cOIll ribt. iun of e,1(h forcing var}ing among ft.'giuns (Supplenlt.,11'll"Y T,~)le 54). lhe sanJe fon:ing s are likdy lo haw played a similar role un a [unf,'er 1inJe~ale lh,11 ill::Ju,b 11~ elll i re fu">l. millennilllll. For ex,mlple, sonJe rt'Cor,ls 01' \"C.Jcanir 'o and solar " aclivil ie; (Hg. 4f) silO\\' significanl long-leml r~,11 iw folt~ing owr lhe las!. 1,000 }"t' Jrs (l,'lann-Kendalllrend le>l., P < 0.05). l'urthemlOre, in lhe Norlhem Hellli~phere mid 10 high lalilu,b, 11~ millenniaJ-scale cuoling cm 1)C ascra)Cd lo an orbilalJy ,lriwn ,h:reasc in [ocal stlllllll<T insola1ion, as sugf,'es1 ed for 1he An:.lk ,. and northern Scan,lill<l\ia'''. 1n 1he Suulhern Hellli!phere, a clinwle modd of inlernlt~,liale complt'Xily sin l. d~e; ,1 nlldl i- millennial cooJing in StUlllller as a ,klayed re~)onse 1o 11")0' ,urea-e in local spri ng i nsolal ion, m Ü\.ll ~ aled by lhe 11~rmal int~J1ia ofl he Soul [~rn Orean'''. Multi-decadal to centennia l variability "[em~)Cnl1ures .lid no1. fh::luale unifomlly among all regions, high lighling 1[~ rt~gional[y ~x'ciflC en:>lulion 01' lelllperalure ,11 nl.dli ,uadall0 celll enniallinJe scales (Fig. 1) . HOI\TYef, 11")0' penud f mm arotUld Al) 83010 [[00 ~nerally erKon~Jassed a sttslained warm inlerva[ in aH fottr NoJ1 hern HellliSJ-:>I-.ere regions. 1n Soulh AnJerica and Ausl raJasia, a ~tlSl ained warm periu..! occurrt~dJ ~ er, f mm around Al) [[60 lo 1370. 1n 11~ Arel ic and EUf(=1x', lemperal11res w~re ft-ia1i\"t-iy high dlll"ing lile fll"sl cenlurie; Al). 1;'[0>1. o11~r rt'C unsl ruel iuns arel00 sll0r11 o inferlelllperal11res before arotUld Al) [OJO. "liJe 1rart.:ilion lo col..!er rt'gional dilml1 e; [xl '''''en Al) [100 and [500 is e\i,knl earlier in 1he Arel ir. Etll"OJ-)C and Asia lhan in NoJ1 h AnJenca or lhe St)t. l~rn Hemi'pllere. DifJeftlKeS rullong rt1lions cotdd reflecl non-forced vari<l1 ions ilwolving lhe nmjor mo..!e; of almmpl")O'ric varbhilily"~'. By amund Al) [5SO, all regions exctV1 Anlan:l ka enleftxl a pro1racled ((~d periu,l Apart f mm inlen"lls of rt-ialiw "'-'giunal warmlh, e~)('(ially ,.tring lhe eigh10cnlh cenlury, NATURE GEOSCIENCE 1VQ 61 ,,-.AY 2013 1....,.,w.nii ure .(OO1ft1ii uregeoscience ~) 2013 Maar ill an Publi slle rs li rr it ed . AII rigllt s re",rv ed '" PROG RESS ARTICLE • NATURE GEOSCIENCE fon:ing (nine 3O-year periods chNeft~d in frw di;;1 incl 30- lo 9O-rear inlerval s Ixl I,,,,---en [15 [ and [810, as dtl enni Ilt~d using cnleria sptl:if1ed in Methods) b~nentlly Cllrft~ond lo a dn=1-' in 11"10' al'tTab~d lempe ral11re (Fig. 4b). Monle Cario sanl,ling ofl he ,lo1.ren,~dglob,tll ime series 5I1ows 1hal Ilr avera~d 1enl"lt'ralure dunng Ihe~ peJ111rl-.ed inlerval s was signifKanlly lowe r (P < 0.01) Ih.an lllO' means of nine randomly sdecled 30-year perio..ts Ixl I,,,,---en AD 830 and [9[0. All he rt.1liomtl se,tle, 1Irse l'oIcanir- and solar-]X~J1l1r1-.edpeno..t,: ilKlu,kllle coole;;1 30-year period ofe,Kh "'-'Con;;1 nr:1 iO Il, all hOllgh llr re~'onse in AI~lmJasia and Norlh America set:'Ins lo lag by one 30-rear period during Ihe nineteenl h ct'nlury (which ilKIlll.lesl he du;;1er of volcanic en~'1 ions be!. wwn AD [813 and [835" ), and Anl arclica was col,!e;l dllfing llr mid,Ue of Ihe I we nlieth cenlury (Fig. 1). NoI all rt.1lions cooJed ,ilring each ofllr;;1 rong volcanic-solar dOl\'nl11HIS. Forexampie, AIN mlasia, SOlllh Amenca and NoJ1h Anrrica 1rt.1;;' rings do nlll sJ10l\' nl.dl i-den ll.lal cooling dllfing Ihe earlie ;;1 inlerval of;;1 rong neg aliveforcing (AD [15 [- [3 [0). Sig nifi ca nt coo ing t re nd • Noo-s;gnifi ca nt coo li ng t re nd • Noo-s;gnifi ca nt wJfm ing t rend • Sig nifi ca n! wJrm ing t re nd St Jrt c( ¡nt ",va l (ve" AD, JII .nd ingJt AD 1900) Figure 31 Surnrnary of long-ter rn tr ends in indi vi dua l sit e-Ievel pr oxy reco rds. Sign (p::>~ tl v e or negall ve) iIld sta tlSllca l signlfl ciflc e 01 the slop e 01least-sq ui'I"es Il neil" regress ion t hrough eao::: h slte-leve l proxy record w lthln the PA GES 2k data se! Th e frao:::tlon 01records t ha! e m l ~t sign ifi ca n! (P < 005 ) or n on -signl ti Cifl t coo ll ng trend s w as ev aluated for record s extend l ng bao:::k d Ifterent length s In 30 -year steps Th e loo ge r th e record . th e m ore li kely 1I 15 l o e m l ~t a ~ gn lfl ca nt loo g-term coo lng trend. For Ill ustra tlon purp::>s es , th e Ira-::: tlon 01pos lt ive trend s \'1 1th magn Itu de slll all er (1igtl t red) and larger (red ) th ifl the one-sided P = 005 1eve l is also Included cold condil ions prevailed IUll illale in Ihe nineteenlh cenlury. Again, llr allernal ive m::on;;1 rucl ions show palleHIS similar lo 1hose of Ihe PAGF51k ",-~ional rt.l:onstrucl ions (Sllpplellle!llary Hg. S4). PaJaeoclinwle ",-'Cords Sj)anning llr past millennillm are onen characlenzed as indlll.ling some manift~al ion of a warm ¡"'~dieval Wann Penod (MWP ) follow\:xl by a cool Li11le Ice Age (lJA)". Prt.-~viOll'> re\iews oflhe~ inlervals h.1\'e shol\'n a lenden::y for cenlennial-seale Itlllperalure anomalies, bul have al;;o elllph.lsi7.ed 1hdr htlerogtlleily Ihrough ;pace and 1illlc"'-". Our ft~gional lelllperalure ftl:on;;1 rucl ions (Hg. 1) al so shul\' I i1tl e e\i,~nce for gloI,ally synchroni7.t' d nlldl i-,nadal "hifts 1hal wOldd mark wdl -ddilled workh,i,k ¡..nvp and LJA inlervals. In;;1ea,lllr ;peciflC liming ofpe ak warm and cold inlervals varies regionally, wilh ml~li - deca,bl variabilily rt.~dling in l"t.'gionally speciflC lemperalure ,kpaJ1ures from an un,hlying gloIxtl cool ing 1ren,l Ollr l"t.~ional lenyeralure rt.nlll;;1rllclionscan be compaftxl wilh ftl:or,b of solar irradiance and \'oIcanir acl ivil y 10 examinelhee:l.1enl lo which lemperalure changt~ coinc i-k wil h 1hese dimale fon:ing s. lhelime series of area-wdghled, standardized 3O-year-llIean lemperal11res averab~d ae.ross all rt.1lions (Fig. 4b) displays broad similaril ies wil h rt.l:or,b of dimal e forcing s (Fig. 4f.g), a fealure also ~pare!l1 in pre\io1l5ly pllblisJrd rt.'Constrllclions of Norlhem Htlnisphere averab~lemperalure (Fig. 4a). "1 hq¡eno,b of mo;;1 Ilt-~galive \'okanic-soIar '" 001 WW"/NGEOP" Twentieth-century reconstru ct ed t emperature lhe Iwenl ieth cenlury ranked as Ihe warmc sl or nearly Ihe warmesl cenlury in ,111 regions excep1 Anlarclka, wht~re llr large lhermal ineJ1ia of lhe surrOllllding ocean may ,Llll1l-.en warming" . Exdllding Anlarclica , lile IWtlllieth-cenlur y awrab~ lemperalure among lile six rt.~ions was al:>nt. 0.4 oC higller Ihan lhe al'tTagt~d l eml-.eralllrt.~ of Ihe prt.'OCding fll't' cenluries (Strfllemenlary Tal:>!e S3 lists cenl ennial Itlnl-.eralure di1TerelKes based on lhe PAGES lk and all e rnalil't' rt.'Con;;1ru:lions) . Compa",-' d wilh Ihe pft'Ceding fll't' cenluries, Iwe nlieth-cenlury warming in Ihe four NoJ1hern Hemisphere regions was, on average, abolll lwke lhal of Ihe more ;;1 rongly LlCean-dominal ed rt.t;ions of Aus1 ntlasia and Sm. h America (abOl. 0.5 oC c ompaft~d wil h 0.1 OC) , I,il h Ihe greal esl ,lilTerelK.es al noJ1lrrn high lal ilude;. Twe nl ieth-cenlury warming in 1he Arcl ir (0.9 OC) was abm. 1h"'---e 1imes Ihal of 1he al't'rage ofllle oIller f11't' non-polar l"t.~ions. Oll/" besl es\imal e of rt.'Con;;1 ru:.led 1enl"lefalure for AD [97 [- 1000 can be (()mpa",-~d I,ilh aillllher conSfft.ive 3O-yt'ar perio..!s I,ilhin each "'-~gionru "'-'Con;;1 ruclion. In Asia and AI~lralasi;~ rt.l:on;;1 nlCled lemperalure was higlrr ,ilnng [97 [- 1000 Ihan an}' llIher 30-rear peno..l "Ihe Arclic was al;;o warnJe;\ ,ilring 1110' lWtlllietll ct'nl llf}', al1 hOllgh warmer ,ilnng [~[ - [970lhan [97 [- 10J0 accor,ling lo Ollr rt.nm;;1nlClion. In Sc.... h Amerira, lile AD [97 [- 10c0 rt.l.~ on;;1nlcled lemperalure was similar lo Ihe "'-'Cord ma.'li nl.lm in AD [15 [- [18U In Norlh Amerinl, llr "'-'Corl.;J rucled lemperalure for Ihe [97 [- 1000 inlerv,tl .loes nol ilKlu,~ Ihe warm dtl:a,~s silKe [98U and Ihertfore un,~re;;1 imales 1110' aclual lempefalure for thal inlerv,tl . In EtlfC1X" sJigl11ly higlrr ft'Con;;1 nr:led lemperalllrt.'S I''''-Te ft1li;;1eft~d in AD 74 [770, an..t Ihe irl1erval from Al) 1 [- 80 was st~'slanliaJl}' warmer Ih,U] [97 [- lOCO. Anlarclka was prol'al:>!y warmer 1han [97 [- lOCO for a lime perio..l as rt.yenl as AD [67 [- [700, an..! 1110' enl ire period f rom [4 [- [150 was wannerl han [97 [- 1000. lhese irt et}'ft1a1 ions are b~n erall}' st ~vorled by Ihe ft'lalil't' magnilu,~ uf rt.n'lll 1'~lrming in Ihe al1erml1 il't' ftl:on;;1 nlClions ( St~vlenrnlary Fig. S4 and Dal abase 52). Each in,lid,ital pro:l.)' "'-'Cord conl riblll ing 10 llr rt.~ional rt.'Con;;1 nlClions was analy~d lo evaluale wl"lt'1.her 1he v,tlues ,ilring [97 [1000 in,lical e higher lemperalures l han fUf an}' llIher 30-yearl"lt'riod (Fig. 4d,e), indepelh~nl of 1he procedures used for cal ibral ing lile lemperalure rt.'ConstrtlCl ions. According lo Ihis analysis. of 1he 313 indivi,ilal prm)' rt.'Cords Illal exlend lo Al) [500, more sil es seem warmesl dllfing [97 [- 1000 1han ,ilring any 1lI1rr 30-year l¡erio,l bol h in lerms of 1he 101 al numl-.er of sil es ¡lnd Iheir prq,orlion in each rt.~ion. Similarly, of 1he 51 indilidual ",-'Cords 1hal exlend lo AD 500, more sil es (and a higher prq'orl ion) seem warmes\ during 1he I wenl itih ct'nlll/"y 1han ,ilring any olher cenl ury. "1 he fracl ion of individual rt.'Cords 1hal indkales Ihe lligl1esl lempenl1uft~ during [97 [- lOCO ,nreases wilh inc reasing ft'Cor..! lengl h, consistenl wil h an ol't'rall cool ing 1rend owr 11"10' pa;;11 wo millennia (Figs 1 and 3). NATUREGEOSOENCE 1\.U 61 ,,-.AY 2013 1...w '.....nJtur HOO1/ nJtu regi'OSC il'l1c. ~) 2013 Maarill an Pub li sllers li rr it ed . AII rigllt s re",rv ed NATURE GEOSCIENCE PROG RESS ARTICLE 001 WW"/NGEOP" • b , ¡ , u O d • " O , e ~ ~ " o ~ g , e ~b " ~ o; ~ , o " '"""''"' (S hap rol - - - Scü r-wea k (Vie iral - - - Vo lca nic (wo l - - - Vo lca nic (C row ley ) -0.5 -1 5 h ------- 15' S Ju l e ~ , N Jul - - 65'S J, n ~ e < Ve" ~ D Fig ure 41 Co rnp osit e ternp era tur e reco nstructi ons w ith cl irnat e fo rci ngs a nd pr ev ious herni sph ere-scale reco nstr ucti ons. <1 , Prev iously pub li shed North ern Hemls ph ere 30-ye ar -m ean temp eratur e reco n s true ti ons relabve l o th e 1961-199 O referenc e pe riod""'" b, S tan dard ll ed 30-ye ar -m ean tem peratures ave rage d ac ro ss all seve n cootlne ntal-sca le regio ns . Blue symb us ar e ar ea-we ighted aJ erage s uSlng do maln are as IlSl ed In Ta~ e 1, and bars sho.'V l\ve nty- fl fth and seve nty-flfth unwe ighted percentll es lo ill ustr ate Ih e v ar i a~ ll ty arn ong reg ioos; open ~ a ck box es are un we ighted medlans. Th e red Il ne is th e 30 -ye ar-ave rage annu al globa l tem pe r ature from th e H adCR UT 4 ( rel 29) instrum ental time series relatlve t o 1961-1 99 0 , and sca led v isuall y to m atc h th e standard ized values Ol er th e Instrum ental period e, Runn lng co unt of th e numb er of regional recoostr uct loos . d, For eac h 30 -ye ar period slnc e AD 1500 , th e proportlon of Indiv idual proxy record s wlth ln eac h regioo th at Ind ica t e th e highes t tem pe rature dUrln g tha t 30 -ye ar period . " For eac h century sinc e AD 500, th e proportion of Indiv idual pr oxy records w lth ln eac h regioo th at indica t e th e highes t temp era tur e dUrlng that century f, Long-t erm v ucanlc forc lng fr cm ref 16 (blac k curve; spikes bey ood - 8 W m-2 are truncated), and sua r fom ng frcm ref 17 ( red curve) . g, Rad lat lve forc lngs relatlve to AD 2000 smoo th ed uSlng 30 -ye ar ave rage s from ref. 31, Includlng tvvo estlm ates 01v u ca nic forc lng'"" ; tw o est lmates of sua r forc lng that span th e range lrom stroog" l o we ak<9; and we ll- mlxed gree nhou se gas es relatlve lo AD 8 50. h, Change In summ er (J u ~ and Janu ary) Inso laboo at 6 5° N/ S and 15°N/ S lat itud es relat lve to AD 2000 fr cm relSO. Ve rt ica l red band s Indicate v ucanlc -so lar do.'1 nturn s as defl ned In Me thod s NATURE GEOSCIENCE I VQ 61 ,,-.AY 2013 I ...."w.nii ure .(OO1ft1ii uregeoscience ~) 2013 Maar ill an Pub li sllers li rr it ed . AII rig llt s re",rv ed PROG RESS ARTICLE NATURE GEOSCIENCE 'll~ art'J-\\'~ighled a\'eraf,~ uf 11~ l",,~ eslinwle of pas! lemperalure fmm a11 5eWll ~--gions indicalesl ha! [g¡ [- 1000 was warmerl han any oIlyrlime in 1lt."'"Jrly [,400 rears (Pig. 4b), ko:'l)ing in mind Ihal Ihis analysis .loes nol consider ll-e tUlcenainly assucia1ed wilh tl-e lelllptcTalurt' Nilllale~, and lila! Ihe rt'Con;;l n l~lions are uf difkrenl lenglhs. Area-weighled aYt.,.af,~'S uf ll-e thrt:-e alterna! ¡ve ro::onslructions f,\:=nerally St ~=1)orl Ihis rt~dl ( Sl4-l"ll en ~nlary Fig. SS). Larf,\" llllCeJ1ainlies "'lmin, e~iaJly dllfing lile fiN millenniull\, wl-en only sollle rt1lions are rqlfl,~nlell H.egar,Ut~S, ll-e global warming 111.11 has occurred since IllO' end of1l-)O' nindeenlh (ert ufy fe\'tTsed a persislenl long-leml global cooling lren.llhe increa-;e in <\\'tTa~ lemperalure 1X1.\''l--ell Ihe nine1.eenl h and IWtlllie1h cenluries excetxhll he lemperal ure dilkrenre be1I\Ttl l aH oIl"fr conseculive cenlurit~ in each rt.'gion, excEpI Art an:1 ira and Sol. h America. '11)0' PAGF5 2k No work ",yor"'¡ rucl ions show dear rt."'gional exprt~sions of lempemlure variabilily al Ihe ml~li - decadal lo cenlennial 9.:.ales, wl"freas a long-Ierm cooling I "'lId before Ihe I\\\:lll ieth eenlury is e\ilbll gloI,ally. Cmlennial -scale lemperalure chan~'S in Al"'¡ ralasia and Sol. h Amerka b\"nerally follow Ihose ofll"f Norlhern HeJlli!pl"fre regions, wl"freas len l~nlure chanb\"s in AllI arel ica do nol. corm al e \\;Ih Ihose of oIl"fr regions. lhe prt'-IWtlllie1h-ctlllmy long-Ierm gloIxtl woling I rend is e\ilbll in difkren::.es in avenlb\" lempemlure be1 I"''ell n J. ~1 i-relll eJlnial periocl,;, and in I he signiflCallCt' of Ihe sl'-V"-~ of kasl - S(p. IM.~ Iilrar "''gres.-;.ions for bol.h Ilr "'1.>:iom~ "'YOfl"'1 ruclions andll"f indi\il\.ml sile-Ievt':l pro:l.)' ",yorlk Our ",yonsi fl r:1ions and proxy-dala conl,il al ion wilJ be l~ji.~ in fulure sludies, serving as a benchmark for comparisons wil h dilmlle modd siml ~ a I ions aimed al lUll\ersl anding 11"f cm~ of 11"f glol,al cooling, ,Uld 11"f e:l.1enllo which e:l.1ermtlly foret~d arlllunfon:.ed variabil it y can explain lempemlure jl lCll~ll ions and I renlb alll"f colll inert al scale. Meth ods Dala sources. AH pro:l.)' ",yords usal for Ihe reb>:iomtl rtyonslntclions are ineludt'l.l in Stl'lllenJenlary Dalaba-e 51, and are an:hi\Td by Ihe NOAA \\'orld Dal a Cmler for PaJeoclimalology (www.ncll:. noaa .g()v/prue()/pab't~s2k/pab't~s- 2k- llt1 \\'ork.h ntl ) . AII regiomtllemperalure rtyonsl n r:1iOll$ are indulhl in Supplemtlllary Dalaba-e 52. Relalion between prm)' reconis a nd lempera lure. "liJe sign (posit ive Of Ilt1jal ive) of Ihe rt':lalion be1wt~n each proxy rtl.~ord and leJllperalure islisled in Str plenJelll ary Dalabase5 1. ll)O'~ ",':I aI ions \\'lTelkiermilrd lL$ing dilkrelll ~'proa::l"fs for dilk:Ttlll rt1jillll$. In Ihe Arclic, 11"f ",':Ial ion is adq.:>led fflM l1 Ihepl ~--.lical ion ofll"f origin.lI ",yords, In F.llrq"lt', Ihe 11 ilp llS lo Ihe rt1jionru rtyonsl m:lion indul~ 101 "'~ ring composiles ,uld docllll)O'nlary e,ilblCe, rul calibmled I oleJllptTalure. ll)O' Norlh AnJeJica pollen-hased rtyonsl fl r:1ion ,tlso rdies on rt.'gionru synlheses Ihal I",~ re p revioll"Jy I mnsfornJed illIol eJllperal lUT. For Asia and Anlarel ica, only m.::ords wil h delllonsl mled posil ive cor",':Ialions ",ilh local or rt.1.>:iomtl (re~livdy) irl.J.fllllltlllal dala ,\\:re irlCIUlhl in Ihe m:onsl flr:lions, liJe Asia, Norl h An)O'rb I rt~- ring, 5ed h A merica a nd AlIsI ra1 asia ",YOrl.J. fllCl iOll$ \\\:re basalon pri Il:ip,tI compollelll rt1lression nltihods, whert'hy indi,il\.lru pro:l.)' rtyords COl ~ d cOlll Jihl. e \\ilh eilher a posil ive or Ilt1lal iw lenf't'ralure rt1 alion wil h dilkrenl prin:ip,tI comJX)]lelll s, or for ememl--.l e nleJllbers wilh dilkrelll inslJllllJelll ,tllargtts, In Ilr Norlh Amerka Irt~- ring "'YOI1'.'l fllCl ion, 11"f sign of Ihe cOlll ra' ll ion for ea::h rtl.~ord cOl~d vary ~)alially as wdl. ll)O' sign oflhe ",':Ialion ",ilh lenl"'-TallUT for 11"f~ "'1lional "'Y0l1'.'l fllCl ions Iisted in DaI aba9i:" 5 1is ba-ed on Ihe di m.::1 ion ofl he rt1,1I ion be1I","'en Ihe proxy m:ords amlllle area-ll'eigh ed a,'tTa~ nJe,Ul anlll~lIlen l"lemIUre fromlhe domain areas in Fig. 1 using 11"f HadCRUT4 (ref. 29) dala 9i:"ries. Sign ifi canct' of Irends. "1 he signi(¡ea nce of long-Ierm cooling I renlb in Ihe ",yonsl m:1 iOll$ (St w lenJelll ary Tal--.le 52) arlll in Ihe indi,idual sile-k ... d pro:l.)' rtyords (Fig. 3 and Str~--.lmlt'nlary Hg. 56) was ealn~,lI ed allhe P = 0.05 con(¡derlCe 1e\'d using a Olr-silhl Stlldelll's '" 001 WW"/NGEOP" t -It~ , while accounling for lag- 1 ;J.llocorrt1al ion in bol h 11"f c<tln ~ a I ion of standard tTrOr and in indexing Ihe t- VallJeS~). lrends in Ihe indivil\.lru proxy m.::orlb (site len.':I) lI'ere dctermined by fll"Sl invert ing Ihose proxy m.::orlb: having a negal iw corrt1al ion wil h leJllperalure (as l~~rihed ahove). "liJe pre- l900 I rend in eac.h ",yord was analysal for SllCet-'Ssi,\'ly sllllrter segnltllls oflime, bq,>:inning I-;Ih I heml irel inf 9i:"ries, Ihen I flulc<lIingeaeh series by 30-}'ear illl ervals, wilh each St1.'lIJenl eJlding in AD 1900. "liJe I rend in eoch I fluKaled series was dtiermhled byllle 5Iq"le ofils linea r regression. For illusl raI ion pUfpOses. Ihe fracl ion of posil ive I rtlllls wil h magnilul~ 1arb~r I h¡U11 he lllr-silhl P = O.u.; le\'d are sllOwn in Hg. 3. Volcanic-solar downlllrn s ( Figs 2 and 4). \Ve analy~'.,xllll'olime series of St~ar forcing an..! Iwo of ,'oIcank fon:ing from ref. 31 (Hg. 4g), 11"f ,'o1canic StTies from ref. 16 (Fig. 4f), and Ihe solar serit-'S f rom ref. 17 (Fig. 4[) lo discern periolb of sl ron~~ agrt--enlt.'ll and magnillllle of fon:ing. E¡¡eh I inJe series wa-; binllt'l.l illl o 30-}'eaf inlerv,tls I h.al coi ncil~ w iI h 11"f Itlllperalure m.::onst fllCl ions (bi n cml rt.'S f rom AD 845- 1985). llf eighl bins (21% of each m.::ord) wil h most neg;¡liw fon:ing ,,"tTe sdecled from eac.h series: II"fn, Ihe subso of bi ns llIul ~"'P i ng amor¡g al leasl one· h,lI f (;:>:3) of Ihe six I in)O' StTieS was icbll ified. "liJe nille 30-reaf bill$ llefuled I his way comprise I he (¡ve illl ervalsl hal weleml 'yoblllic-solar llowlll uflls': AD lEl - 131o, 1431- 1520,1581 - 1610, 1641- 1700and 1791 - 1820. Tempera lures during \'olca nic-solar liown lurn s. To evalual e wlltiher lem~"leralllft~ lI'ere sigllifl.~anlly 10WtT l\.lring illI ervals of neg;¡liw dimale fon:ing, 1I'e implenltllled a Monle Cario procedure lo randomly sanl'le Ihe area-wdght'l..l regionallem~"leraIUfes bt111'l--en Al) 831 and 1910 (we excJlll~d Ihe warmlll'enl itih cenlufy (Al) 1911 - 2000) lo nmke Ilr les!. more conserval iw). For e,\(h of 10,000 ileml ions, Ihe nJe¡UlleJllperalure of nille 3D-yeaf illl erv,tls was calnd alell lk\:au9i:" most of Ihe inlervals of Ilegal iw forcing oc.em Ialer in Ihe ",yord, I he lo\\' lempenll llrt'S l\.IJing Ihese inlervals may l"le parl i<tlly dl~ lo long-Ierm cooling. "[o assess I his possil'il it y, we ,tlso conl\.lCled 11"f les! on Ilr dtirtlllkd art\l-wdghl t'l..l nJean. For bolh Ihe oJigimtl and lb renlhlle~ s, 11"f nJe¡U1 of 11"f nille illl erv,tls of negal ive solar and ,'oIcanic forcing wa-; IOIl'er Ihan more Ihan 99Ji¡ of Ihe nJe,UlS of ranllomly selecled illl erV<tls (Ihal is, P < 0,01). \\'armesl inlervals wilhin individua I proxy reoonis (Fig.4d,e). Silelevd wamJes!.-inlerval ¡uJalysis was COndlk:lt'l.l for 30-p:'ar illIervals spanning f rom AD 1491 lo 2000, ¡Uld for l00-}'eaf inlervrus betllTtll A D 501 and 2000. Proxy ",yorlb 1I;lh Ileg;¡1 ive cor",':Ial ion wil h lem~"lenllure WtTe inverlell Only m.::orlb wilh alleasl one nJeaSlUTnleJl1 in e,lCh 30- or l00-}'ear bin were U9i:"ll. "Ihe Ihrt~ I "''e-ring ",yorlls f rom norlhern FennoS(.¡Uldia, \\'hich wtTeusal in bol h Ilr Arel ir and I he rurape ",yonsl flr:1 ion.~ , lI\::re ilKlulhlonly once in I he sile-Ievd analysis. liJe warnJe~ inlerv,tls lI'ere ic~nli(¡ed by ranking Ihe val lIes of I he 30- or l00-}'ear bins for e,lCh rt'Corll lo betltT "'l're~nl rt1lions wil h ft""lTr ",yorlb, Ihe vruues 1I'l~re prt~lll ed as 11"f froclion of ",yords in eoch region, ralherlhan Il"f llllllll:er of rtyorlk liJe f I"<\( lions lI'ere scrued SllCh Ihal a V,tll~ of 1correspon..!s lo ,tll ",yorlb in ,tll regions. Received 9 December 2012: accepted 11 March 2013: pllblished online 21 April 2013: corrected aft er print 14 May 2013 References 1. !locksl ru m. ). el ,,1.1\ ,>le oper>l',ng 'p.ee lor hum .n "<I r. Nm"" 461, 472 -475 (20 09) . 2. Snrder. C. W. Ih e va lue olp. leocl'> m'l e",,", rdl 'tn our d,.nging d ',nw e. C/,m. O""'ge 1m. 407-4 18 (201 0). 3. nr:tconn(J(.l'. el "l. ha ltw'ton old·t m.le moJel, us, ngp,ürod',nwk J .... N,¡¡"r, Cltm, Ol""R' 2, 41 7-424 (2012). 4. DNcr. C..l'lllil·!" , A.. nourdrtle. V. & re ng. H. U",: e ~"tnt r 'tn d·,m .. e d,. nge projec(Lons: lh e rul e of'Lnternal "" .. br Ll )'. Ckm" D)"!: .\8. 527 (20 ll) . NATUREGEOSOENCE 1\.U 61 !>.'LAY 2013 1",w"".nJtu re.(OOl/ nJtu regi'OSC il'l1c e ~L 2013 Maar ill an Pub li slL ers li rr it ed . AII rigILt s re",rved NATURE GEOSCIENCE PROG RESS ARTICLE 001 WW"/NGEOP" 5. .\!>n n, .\1. I. f1 al. I'ruxy-b.,cd reconSl rucfLon, 01h" misf'bcr\c >nJ ¡;loo. l ,urtúc l"mprnlUfC van.tions ovenhe p.SllWO mül"nni •. ¡'n'c Nml 11",,," Sci. USA 103.131 51-13257(1008). 6. .\!>nn . .\1. I. el ,;1. Gl obal ,ignmm" .nd J)'n.m't(.l origins otlhe Lin l" kc Ase . nJ .\lc¿',,,,' Jl el,m 'l" Anon,.I)'. 'idm,c 3;);, 12 56-1260 (2009). 7. Funk. n.. href. J•• Zoú., I. & Wil",n. R.A nooJl", ¡'""kry sI',ck.• nd sp.ghrtti rl.t c, • pr"p",1 '~'c O) n 111gh- r." o/u 'Lon palrod'Lnw ology. \V/II b e km. Cir.mge 1.5 07-5 16 (2010). 8. KLdlOl,on. S. I. ('1 "l. le mp""I"''' va'ÜbU'Ll)' over ,\1,,(, Junns th" I.Sl 1000 i'N" . JI" n,iMmf http :// Jx .Joi.or¡!/I O.1177/U9 5968 36134836 18 (1013). 9. 1',\GI' S/Ckc> n2k Work'Ln¡;Groey. S¡: nlh ",\s 01 m>rúl C s.rJi merJ-Je¡'¡vM SS l ' ,,,,ord, 10ft 1,,, 1'.,1 2 mü!rnn '.. , F trsl -orJe r r",u1l , Imm Ihe P,\G IS/Cke.n2k pm)e" .1\GU F. U.\ !eeü ng .• b>lr. 1'1'11 1'·07 (A mer"o.:.n G""rh)~ic'¡ Un,o n.2 012). 10. Chr""h. n",n. JI .• Sd1müb. r. & lbejll.P.1\ "tITOg. ' e en", mDle Sl to.:l)" 01 dinwe recon;l ruction m rthoJs: SI o..1,.,l"te '1 r .nJ robuSl nes<. J ek'm. 22. 951-976 (2009). 11. ISf'er. J. & Fr>nk. D. e. Dinr¡;enee r'tttalls in I ree-ring re",,,dl. Cl:m. eh.mge 9-1, 261-266 (2009). 12. Jon",. P. D. & ~I>nn ..\1. I.CJ"tnw e onr r'Sl núllenni> .II"v. G"vl'''>"-' 42. !lG2002 (2014). 13. Cro", "}' T. J.C",,,,, old'tn,., e d,.nge onr lhe p'Sl 1000 Srim,f m. 270-277 (2000). 14. Jlmer. I.. CJ.",,,,n ..\1.. JlrO\'ki n. V. & HuenerN'tn. J\. I\'='tng d 'tm .,e toreü1g' ol lh e h t1h '}~le m tonhe r'Sl m,"lenn 't um. G"'l'iry', 11 .., I.m, 30, 1276 (2003). 15. H"Se rl. G.e. fl "l. in Chmmr Ormrge 2oo7, '¡¡" I'Jo)'i",1 S"<'t"f B,,,,i, (eJ, S,~ o m o n. S. ,! ,,1,) (C. mbú:lge Un '~'. Pr"". 2007). 16. Goo,,,,. II.. Cro",ley, '[ J.. 10r'1" I.. Amm . nn. e. I .. Renssen.ll . & Dti",sd1Hn. I. .\!oJd l'tng 1be d'tn,.,e of Ib e 1>" m 'ili en n'~tnl: Wh., e"",,,, Ib e J 'u fere ne", I",'",ee n ,imuht'ton,¡ Gf"I~')~ 11 .., /.w. 32. 1.06710 (1005). 17. Sle'ullúlb er F. fl ,,1 9.4 00 FH' 01 eosm'tc nJüt'ton . nJ "~H .ct'I\' I )' from \ce core, • nJ I re e r'ms, .Proc. Nmlll","- Sci. UN, 5967-5971 (2011). 18. Kt'tl-n,.n. D. S. el ,,1 Ileeen l "'. müng re"""",, long-l eml A 'te co'~'tng. S"m" 325.123 6--1 23 9 (2009). 19. ISf'er). el ,,1, Oruilal toreing oltree-r'mg J., •. N"wr< C/,m. O"~'ge 2. 861-866 (10 12). 10. !lenssen. H. Goos",. H., F\.:het~~. l'.. .\1>,,,, n- Dd nlOl1e. V. & 1< 0.;. N. lh e HoIoc ene d 't n,., e e\'ohl 'ton 'tn Ih e lúgh-1>t'tluJe S oUlbern Hem 'tSf'bere ,imuhl ed by. coupled >1moSf'bere-,e. 'o,:o-oeNn-wg<w 'ton moJd. '/I,e flo",,,,,,e 15. 951- 964 (1005). 21 . Fe rn .i nJel- Do n. J o. L. el ,,1 hrg<-,n le le nve mure r'''pon", 10 exler nal tore 'mg 'm ,imuhl'tOn, .nJ reconSll\lct 'ton, of Ihe l." m'"l en n'~tm . e km 1'.«1, 9.3 93-421 (2013). n. Goo,,,,. 11. el ,,1, 'lhe ",le ollorei ng . nJ 'mlem.1J)"n.m 'o.:s in e,pl ' tn'tng Ih e ·.\!e Jieva.l Clim m Anomal )': el~", Dy", 39, 1847-1866 (1012). 23 . I..mb. 11. 11. 'lb e eu~' meJien l ",um 'l'0dl.nJ 'tl' ,equ d .l'al.;e"!i';>gr. 1'.;I,;eo",,,,, 1. 13-37 (1965). 24 . IInJl "}'.IL S.. Ilugh",. ~1. L & I)'..l. 11. E d'tm >1e in .\! ed'tc... llime. "dm" 3m , 4¡¡"¡--4 05 (200 3). lS . .\!>11 1",,,~, ).1\. & lIr'u!'. L Il 'lh e "L't1t!e Ice Ag<', Ue- eva. lu.t'ton ol. n "vol v'mg co neepl. Gr,'1I" 87 A , 17-36 (1005). 16. ljun¡¡'I''-tSl. Ee.. I<l\Iso.:.p. J.. !\nI1 Slro m. G. & SunJqv 'tSl.II . S. Non l",m Il em 'tSf'bere 1emp er::tlure 1'.11 cm, 't n 1be 1>Sl 12 een lu "," . e¡,,,, 1'.<-11 S, 117-149 (1011). 17. Dial. 11. F. el ,,1 Sp. t'tal . nJ lemp oral d,.ncte""'tc, 01 d'tn,.,e in .\ !e Jie,.. 1t'tm", r,'\' 'ts't1cJ Bu IJ, 11m. .lIm.'n,l, "oc. 92. 1487-1500 (1011). 28 . St ",ufer IL ¡...\I>n.be. S. & IIr}" n. L I nl erbem 'tSf'l", "e ,,}' m mrt ry 'tn d'm,,'e r"'P0 n", 1o • Sr>Jeul 'tnere.", 01>1 mosp¡'eti( ca,. NIiWrf 3-12. 660-661 (1989). 29. Jon",. 1'. D .. LiSler. D. I!.. O,ho rn. r. ).. I!>tpl,.m. c. , S. lm on ..\! . & .\!orú.e. 1'. Il em'tSf'bene • nJ l. r¡;e-scale bnJ sut1>ce '-'n emf'" r::tlure v u'..t'ton" 1\ n exlen"n r,'\,'t"on . nJ.n ' y J>t elo 1010. J Gf"I~'>"-" 11"" J 17. D05127 (1011). 30. S.nl er. 11. D. el ,,1 S1>1 bf,(. 1 ,isn ',[«.nee 01 trenJ> . nJ I re nJ Jüferene", 'tn I.)'er-.wr::tg< >1 m"'f'b ene lemp ef>lure time ",r'L"'- J G")I~r)' lIe.', 103. 733 7-7356(1000). 31. Sd, m'te! . G. A. el ,,1 Clin,., e lorc'tng reconSl ru.:t'ton, 10r u ", 'Ln P.\!IP ,i mul>t'ton 01 Ih e 1..1 m 'j len n'~tm (vl.1 l. Gf,"ci. .\10"" Df1< 5, 185-19 1 (1012). 32 . 1!>nhijirvi. S.. l"tngley. ~!. 1'. & Korbol •. 1\ . l'iLr",i, e co mp' n,on, 1o reco "" ruct mN n lempenture 'm Ih e 1\ ,,1't( 1\ I1>nti( r"S'ton O\'en l,e I>s11 000 )-'C>!'S. eli", Dytr, bll p'¡¡ Jx .JOt.or¡>.i 1O, 10071>80 3 82-0 13 -1 70 1-4 (2013). 33 . l\ün1sen. U. el ,,1 25 00 F'!'S ofl'u ropN n d'tm>1enr-..b'tlüy . nJ hun,.n ,u,apltb,"'t1 y. ~;;im", D I, 578-582 (10 11). 34 . Dobrovolil)'. 1'. el ,,1 .\!o nllll y, ",>so n.l. nJ . n nual le nve r::tlure reco nSl ",,1'ton, lor (enl r::tl htrop e Jd~'ed tmm Jontnle ru r}' ",'-tJenee . nJ inSll1.tnlent>1 record, , inee Al) 1500. C/mr. eh.mge 10 1, 69-107(1010). 35 . C ook. I.!! ,,1, Tree-r'mg recOllSlntcteJ ,unlmer temp enture .non,.li", lor le mp ente hSl A, -.. ,i nee 800 C. I. ebm. Dy", 111p:/i Jx .Joi.o r¡>.i 10,1 0071 .00 3 82011-16 11 -x (2013). F"'. re' A"", 36. Walll. I. R. & Smerdon. ¡. L Co mpu::tl 'tW pet1-ormanee olp. leo..1'tnl>l e f,dJ . nJ inJex reconSl I1.'" 'ton; Je "nd trom d'tnwe prO.\i", .nJ noi",-oru r pred'tctor" Gevl~ r)', 11", /.,!I, 39. 1116703 (1011). 37. rmu". v. el ,,1 A 1500 -}'eu reconSl n,,1 ion 01 .nnaal nle.n 1emf'" Wure lo rt e nver:l.le NMh l\mcfK' on Jec>Jal -lo- mult'tJee.cL.l t'tme ".1",. I'm'im" 11", I.ell, bl1p ó/ Jx .JoJ.Ortf 1O 1088/1748-9 32 6,'8/1/0 24 008 (101 3) . 38 . N""'om. Il ,! ,,1, ~ lult'tp ro,y ,um Ol er .nJ ",inler ,,,rÚe e .ir le nventure [,dJ reconSll\lct 'tons lor ",u l1em S",,,h A nl ene. covdtng Ihe p'Sl een lu r'", ,, Cl:m. D),,- 37,35-5 1 (101 1). 39. N""'om. IL &GcrSl<, J. Sou l",m Ilemisphere !ügll-r,'S,~u'ton p.J.",dinwe record, ol lb e b'11000 yem. ,/1", fjvlM"'f 22. 501-524 (1011). 40. Sdlne'tJer. D. el ,,1, A nlu,1ie lemp entur,,, owrlhe p'Sl ''''0 een lur"" Imm '0,:0 cor",. Gfol~ r)" lIe.'. I.!!I, 33. U 6707 (1006). 41 . Sktg. I. el ¡;l Reeenl dinwe .nJ gl >eierd,.nÍ;'-" in \Ves! I\r.luctie. convued ",'tIh Ih e p'Sl 1.00 0 Fm. NIl "re G,;>,d, hllP ó/ Jx.Joi.or¡>.i 1O 1038/ n~'<.l1 778 (10 13). 42 . I'bl<ul.>k't. W. A nlrthod I o e,l'tnw e lile SI >1 l<üe.l ,ignif«.nee 01. eorrd.üon ""en Ih e J.l •• re .er'tal!)' (orrd>1ed.¡, e km 10 , 1147-1153 (1997). 43 . ~ !()ber¡;. A., Sonedlkin. D ..\1., Ilolnlgren. L. Dmenko. N.~!. & K.Mn. IV. 1rtgh!)' nr-..b le No n 1", m He n"'Sf'I", re 1emf'" r::tlures reco nS1 rU':led from 10"'- • nJ lúgh- r,,,oIUI '.,n p rO.\ )' J.,. . Nw "re -133, 61 3 ---él 7 (2005). 44 . L).tn¡;q,'iSl. E e. 1\ ne", reconSl ru.:Hon of lemper::tlure nr'.. b'~ 't1y in 1he exl r::tIrop \.:al Nonhern II emiSf' bere J,tnng Ibe 1>'1''''0 m 'ili enni •. Gf0ll" ,1m,. 92,\ , 33 9- 351 (1010). 45 . lIegerl. G. c. . Cro"'e )', l'. ¡.. lIyJe. IV. '[ & Fume. D. ¡.CEnwe ",nsü,'t1 )' con'lr>'tn eJ bylempemure reco nSll\ld ,on, O\'Cf lh e p'Sl ",w n een lu n",. N.¡wr< 4-10. 1029-10 32 (2006). 46. G.o. c., Uobock. A. &A mm . nn. e. \'oIe.n 'o.: tor.:\ng of d 'tm .,e owr ti", p'Sl 1500 F"" 1\n imp rowd ice (Ore-b ..ed 't nJex tor el'tnwe moJd •. I, Gfol~'Y.' 11", -,Ir","" 11 3. D231 11 (1008). 47. CrOl""}'. '[ & Unlern,.n. ~!. Ted,n 'te.l Je,. '1, (O nce ming J",'dopmenl 01. 1200-Fapro,y 't nJex torglobal ,'oIe. n'Elll. /'¡mlr S)'f, Se., DI<I.; Di,m<.' , 5.1-18 (1011). 48 . Sh.p'tro. A. ,! "l. A ne", 'Wro.d" o 1be lo ng-le rm reco "" ruct 'LO n ol lh e ",lu 'trnJi. nee le.J> 10 luge historical ,,~ u tord~. Asir"" , A<1n'I~')" 529. 1\67 (1011 ). 49. Vidr>. L. I .. S oI .nk ~ S. L. I< nvov.I\. V. & t;.., skin. J. G. ho lul ion ol lhe , 00 u irr.JÜ nee J,tring Ih e lIoloeen e. lI.<lr"", A.<lrol~ ')" S3 1. 1\ 6 (10 11). 50. Jler¡;er.1\. L. Lons-lerm vu'w'.,n 01 J.ilr in""l'.,n . nJ Q,w cm. r)-' dinw ic d,.nge. Q,,¡¡¡, 11", 9, 13 9-167 (1978). Acknowledgments SuW 0rt f or I',\CE S a cti , ;,i <> i , ~ o, ' i JeJ O)' ,h o US "" ' J S"; ,, ;-"ti Ol> '" s .-;." co Fou"J,ti ol> , . US ;-"ti Ol> '" O eo,,", oy ~hi e "-', J ,\t1\' 0'fÍ' cr i e ,\J ,ni"i" " ti Ol> "-,,J ,he Illtcr ",ti Ol> '" Coo'¡;<, cro-H io,¡X,cro I'r ogr,,"llln o, AlJ m ~, """ e lil\ JJ )' ae" eJ O)' Al ", ""' Jcr II cr ,n "-'ll'. 11>" itu'e of Ceog,,¡X, )'. Ul>i ,'cr~')' of I1crl> oy Author Contributions II'ril inllWam : 11.S , K, I, J Ih ••}1l1h " ise KI'..\!cK.. El. &. S,Tll, ¡x~[orlll i'J Ih " .}1l1h ,~ i , '-l' '" )'><>' D. S,K .. R.N .. 1.. I',C " IX, II ,C .. 11 ,W. es ..\1. T. FeL, v..\!- D" E,R,\\'., &. L ,,0 ¡",¡",reJ ,h o ll>,,"' u,,",i1", ,\frka: D.). K, AA . B, .\1. e, S,\\'. C " S,J-:.N .. 1. .\1. S, D ,\ ', A- .\U .. , .\1. U. eon,¡XkJ ""' J C\',"u>teJ ,he 1" 0' )' J,,, , Anl."'''1 ka : 1.1',0 ..\1. B . AD ..\!.. R..\!.. 11. 0 .. .\1.S<.. liS, E,IS ..\1. 1. , j. \\'.e\\'., .\!.A Le LR..\!,C., .\1. Si, &. B..\!. \ ' pr o,'i JeJ I" 0'Y J", , . contr i buteJ ' 0 ,hcir J" in ; ,," ,J i"t cr I"ct,ti Ol>' .\!. A Le, J. R..\ !cC" .\1. ,. , &. B..\!. V corrd"eJ 1" le,,"l ie JI> 1J'lcr,; 1.,,0 &. R.N , pr o JuceJ th e reco,, " ructiol>' .\! A Le ll>.lll'geJ ,h o J ..to , An' lk : AA K .. D,SX &. S, TI 1. coorJi1>", oJ ,h o .. uJ)' S,T I 1. D. S,K, &. re!.. colJ eeteJ ,," lJ m'ie,,"eJ t h e pr o'y J:"", S, TI 1. d eul >teJ th e recOl> "r u,1i oll ,," lJ ,goJ J"" , A"a .\! A . K,IA . I 1.1', H,. B..\1.H .. Q,C .. E,R,e . z. F • KI',C .. K,K .. I',J. K.. T K, J. C ,!'...\1.h. X,S.. D.KS , &. K.Y ,:olltriout eJ. eo1lceHJ ,,",J ""' '" )'><J th e I" 0'y J" '" K,lA . 11 ..\1.11 " E,R,e &. 1',IX ¡xrfom, eJ th e reeol>" ruet iOl>, LK, .\!. S" &. ES, 1" 0'; JeJ t<d",id "'W 0rt "-,,J Jn"-'l ,soJ th o J>t" A"'I "~,,,;a : J. C . A .\1.L, S,J. !', &. R,K coorJi"" oJ ,h o .. uJ)' R,K &. J. C , eolht<J.Jn"",,,geJ ,,",J ,,",,")'.. J ,he I" 0' Y J>t'" RX &. J. C , JC\'dopoJ ,he recol>"ructi ol> ,,'itl, in~ut fr om S,J. !', Ft"'1><' UB " J. E" s ,\\'.. EL. 11..\ k C, EJ. C ,-R .. F e L J.E S, J. !,,\\'. &. J.L colJ e,1 0J. rC\; e,,"eJ ""' J ""' '" )'><J ,h o 1"0')' reeorJ , . "-'1 J ~ o,'i JeJ Ul put Ul t he- ""' '")' ~. "" ' J int cr f"«IJ.ti ol> of the Fur o!",,," , recol>"ructi ol>, S,\\'. m"-,,,soJ the J"", J.l', \\'. &. J. ES pr oJu<xJ ,he r«on .. ru,1i oll, N<>rlh Amer; .... : II.ED ,. E,K Ir, v.1.. R,C .• KC, &. AE.\' Je~gJ1 0 J th o .. uJ)'. ""' ,"),.. J ,h o J>t,. ,," lJ 1" 0JueeJ t h e r« ol> "r u,1i ol> ,; E,R,\\'. &. ,\.l':.\' eolJ eet<J ,,",J :lleh il'eJ ,he J"" , S ()lt~l Ameri,.a RY &. .\1. C , eoor.lu>J.,eJ ,h o .. uJ)'. RY, DAC, A L IA .\!.. .\! S.\ !. !..I',C .. .\!.R ,!', &. AR , l"o,'iJ eJl" o,)' J",,,, R,N, deuht<J ,he r«ol> " r ueti ol>' R,K &. IA .\1. n,,,", ,soJ ,h o J"" AlJ ,uth ~" m'i C"o',.J ,h o In,," l u,,--r il" ''':ll' Additional information Ih o , utho!> Jeehr o ao .."'p.-til>gti1>"",,,i," ir"cr o", Suw<m'<ll'1J'Y inf orm,ti o1> p'p.-'- 01> "'''',,"1> >tUf o, c,"" !I>"uregoo"i <ll ce, Rq" in1> ,,",J ¡xr l\,¡ .~01" i " for",,, iol> i . ",':riJ ,010 ol>li l\ e J.t httf' JII>f'S,J> J.ture, <ol\'¡rq"inh.lllJf'cr m i,~ ol> ' Corr o>!,,", J ... ce ""' J ""UN, for ","'crd • .1, ou1J b o ,JJr",,.J 1 DS K J.Ceom~,,-,li ., t hi . NATURE GEOSC1ENCE 1Va. 61 "'>Ay 2013 1 ....,.,w,nii Ure ,(OOlft1ii uregeoscie nce ~) 2013 Maar il! an Pub li sllers li rr il ed Al! righl S res.erv ed ° ", PROG RESS ARTICLE NATURE GEOSCIENCE 001 WW,"/NGEOP" Moinuddin Ahmedl, Kevin J. An chukaitis2. 3, Asfawossen Asrat 4 , Hemant P. Borgaonkar 5 , Martina Braida 6 , Brendan M. Buckl ey 2, Ulf Büntgen 7, Brian M. Chasé 9, Duncan A. Christie'O,,\ Edward R. Cook 2, Mark A. J. Curran l 2,B, Henry F. Dia zl 4 , Jan Esper 15, Ze-Xin Fan"lb, Narayan P. Gaire 17, Quansheng Ge 18, Joelle Gergis'9, J Fidel González-Rouco 20 , Hugues Goosse 21, Stefan W. Grab 22, Nicholas Graham n , Rochelle Graham n , Martin Grosjean 24 , Sami T. Hanhijdrvj25, Darrell S. Kaufman 26 ' , Thorsten Kiefer 27, Katsuhiko Kimura 28 , Atte A. Korhola 25 , Paul J. Krusi c 2'l , Antonio Lara'O,,\ Anne-Marie Lézine>O, Fredrik C. Ljungqvist'\ Andrew M. Lorrey32, Jürg Luterbacher33, Valérie Masson- Delmotte>4, Danny McCarroll 35, Joseph R. McConnell"', Nicholas P. McK ay 26, Mariano S. Morales 37, Andrew D. Moyl2,B, Robert Mulvaney38, Ignacio A. Mund037, Takeshi Nakatsuka 39, David J. Nash 22,40, Raphael Neukom 7, Sharon E. Nicholson41, Hans Oerter 2, Jonathan G. Palmer3,44, Steven J. Phi ppS44,45, Maria R. Priet035, Andres Rivera 46 , Masaki San0 39, Mirko Severi47, Timothy M. Shanahan 48, Xuemei Shad 8, Feng Shi49, Michael Sigl"', Jason E. Smerdon 2, O iga N. Solomina 50 , Eric J. Steig s1, Barbara Stenni 6, Meloth Thamban S2, Valerie Trouer;3, Chris S.M. Turne~4 , Mohammed Umer ·t , Tas van Ommen l2,B, Dirk Verschuren S4, Andre E. Viau 55, Ricardo Villalba 37, Bo M. Vinther 56 , Lucien von Gunten 27, Sebastian Wagner 57, Eugene R. Wahl 58 , Hein z Wanner 24, Johannes P. Werner 33, James W.c. WhiteS9, Koh Yasuéo, Eduardo Zorita 57 D epartment 01 Botany, Federal Urdu Un iver slty 01 A rts , Sc ience and Techn u ogy, Karach l, 753 00, Pak istan, ' LifTlon t D oherty Ear t h Obse rvatory, Cu um ~a Un ive rslty, Pal isad es , New Yor k 10964 , USA , 'Woods H u e O ceanograph ic Inst ltu ti on , W oods H ole, M ass ao::: hu se tls 2543 , USA , ~ Sc h oo 01 EiI" th Sc iences , A dd ls A baba Un iv ers lty, A dd is A baba , Eth iopa , ' Ind lan Instl tu te 01 Trop ica l Me teoro logy, Pun e, 411 008 , Ind ia, ' Dlpar tlm ento di M at ema t lca e Geoscienl e, Un ive rslty 01 Tries te, 34 12 8, It aly, 'Sw iss Fed eral Researc h In stltute W SL, Blrm ensd or f, 890 3, SWltl erland, 'D épart emen t Pa léoen vlronn em ent s et Paléo cll m ats ( PA L) , Un iver slt é M on t pe lli er, M on tp ~ li er, 34 09 5, Franc e, 9()epartm ent 01 A rcha eo logy, HI StOry, Cultur al Stu dles an d Reli gi on, Un iv ers lty 01 Berge n, Berge n, 50 20 , N orw ay, '1.aborator io d e Dendrocro nologia y C a nb io Globa l, Un ive rs idad A ustral de Chil e, Cas ill a 56 7, Valdlv la, Chil e, "C ent er 10r Clim ate and Res lli en ce Rese arc h , Un ive rs idad de Chil e, Cas ill a 2777, Sa nt iag o, Chil e, 12 A ustr al ian A ntarcb c Div ision , Klng ston , Tas m anla 70 50, A ustrali a, DA ntarct lc Cll m ate & Ecosystems Cooper at lve Reseil" ch Ce ntre, Un ive rs lty 01 Tas m an ia, Sifldy Bay, Tas m anla 700 5, A u strali a, " Co ope ratrv e In stltut e l or Researc h In Envlronm ent al Sc ien ces , Natlona l O ceanic and A tm osph eric A dm ln istratlon , Boulder, Cuorado 803 0 5, USA , "D epar tm ent 01 Geography, Joha nn es Gutenb erg Un ive rs lty, M aln l , 550 99 , Germ any, " Xishu angbanna Trop ica l Bot anlca l Gard en, Ch lnese A cad emy 01 Sc ien ces , Yunn in, 666 3 0 3, Chin a, ~ F ao::: u l ty 01 Sc ienc e, Nepa l A cad emy 01 Sc ienc e and Tec hn u ogy, Khuma lt ar, GP O Box 3323 , Lall tpur, N epa l, " Instl tute 01 G eogr cp hlca l Sc iences and Natural Res oorc es Rese arc h, Chlnese A cad emy 01 Sc ienc es , BelJl ng, 10010 1, Chin a, "'Sc hou 01 Ear th Sc ienc es , Un ive rs lty 01 Me lboorn e, Me lboorn e, V ictor ia 30 10, A u stra li a, "D epart a n ento A stroll sica y CC d e la A tm ó slera , Un iv ers idad Comp luten se d e M adrid, M adr id, 280 40 , Spa ln , ' 1..em altre Center l or EiI" th an d Cll m ate Researc h, Eil" th and LI le Inst i tute, Un iv er sl té e atholi q ue d e LOLN a n, Louv aln ·1 a· NeLN e, 13 48, Belgi um, "Sc hoo l 01 Geogr cp hy, A rcha eu ogy ifl d Enwon m ental Stu dles , Un ive r slty 01 th e W i\\'1atersr ifl d, W lt S, 2 0 50, Soo th Atr ica, "Hydruogic Rese arc h C en ter, Sa n Diego, Cal l1orn ia 9 213 0 , USA , " Oes chge r Centr e l or Cll m ate Change Rese arc h & In sll tu te 01 Geogrcphy, Un iver slty 01 Be rn , Bern , 30 12, Sw itl erlan d, "D epar tm ent 01 Env Ironm en tal Sc i en ces , Un ive rs lty 01 H elsl n ki , H el sin ki , 000 14 , Fi ni and, "Sc hou 01 Earth Sc i enc es and Envi ronm ent al Sust a n iD lll ty, N or th ern A ri lon a Un ivm lty, Flags taff , A rilona 860 11 , USA , " I nt er n a ~ ona l Prc:j ect Olf lce, Past Globa l Ch ange s ( PA GESJ, Bern , 30 12, SWltr er land, '"Departm ent 01 Sy m~o~ c Syst em Sc ience, Fuku sh lm a Un lverslty, Fu ku shlm a, 960 -124 8, Japa n , 29Q ep il" tm ent 01 Phys ica l Geogr cp hy an d Quatern ary G eo logy, Stock holm Un ive rs lty, Stock hu m , 106 91, Swe den , ' 1. abora tcú e d'O céiflograph ie et du Cll m al Exp é ri m e nta ~ o n s et A pproch es Num éri ques ( LOC EA N) , Un lvers lté Pi erre et M ar ie Curie, Paris cedex, 575252 , Fran ce, ' D epartment 01 HlSt ory, Stockh u m Ul lvers lty, Stock holm , 106 91, Swe d en, " N a ~ ona l In stl tute 01 W ater and A tmosph er ic Rese arc h L td ., N a ~ ona l Cll m ate Ce ntre A uc klifl d, 10 11, Z eal and, " Departm ent 01 Geogr cp hy, Cll m atuogy, Cll m at e Dy nam lcs and Cll m ate Change, Ju stus Ll eb g Un lvers lty, Gles sen, 3 53 90, G er m any, " Labora tcú e des Sc ience du Clim at et de l'Env ironn em ent, GIf-sur- 'rVe lte, 91191, Franc e, " D epar tm ent 01 Geogr cp hy, Sw anse a Un iv ers lty, Sw an sea , SA2 8PP, UK, "D ese rt Rese arc h Instltute, Nev ada Syst em 01 Hl ghef Educ ation , Reno, Nev ada 89 512, USA , " Insti tu to A rge ntino d e Nlvologi a, G lac iologia y Ciencias A mb ientales ( IA N IGLA) , CCT- CO N ICET-Me n dola, Me ndola, 55 00, A rg en tina, ' "B ntlsh A ntarct lc Survey, Cam br idge , CB3 OET, UK, ' 9() ep il" tm ent 01 Ear th and En vironm ental Sc iences , Nagoya Un ive rslty, Nagoy a, 46 4 .8601, Japan , "Schou 01 Env ironm ent and Techn ology, Un lver slty 01 Br ighton , Bright on , BN2 4GJ , UK, "D epar tm ent 01 Earth , O cean and A tm osph eric Sc ien ces , Flor ida State Un ive rslty, Tal lahassee , Flor ida 323 08 , USA , "D epar tm ent 01 Glaciu ogy, A llred Wege n er Insll tu te 10r Puar and MiI" lne Rese arc h In th e H ~ mh utl Ass oc iat lon, Brem erh ave n, 27570 , Germ any, "Cu lege 01 Lil e and En vironm ent al Sc iences , Un lve rsity 01 Exe ter , Exe ter, EX 4 4RJ, UK, "C ll m ate Change Researc h Centre, Un ive rs lty 01 New Soo t h W ales , Sydney, NSW 2 0 52 , A ustrali a, " A RC Cen tre 01 Exc ell enc e 10r Cll m ate Sy stem Sc ienc e, Un rver sity 01 New So uth W ales , Sy dn ey, NSW 20 52 , A u strali a, " Ce ntro d e Est udios Cientl11 cos, Valdiv la, Ch il e, "D epar tm ent 01 Chem lstry 'Ugo SC h lft" , Un lvers lty 01 Florence, Sest o Fiore nt ln o, 50019, Italy, " Jao::: kson Sc h oo 01 Geos cienc es , Un ive rslty 01 Texas at A ustln, A u stln, Texas 78 712 , USA , '>t A SG , ln sll tute 01 A tm osph er ic Phy sics, Ch ln ese A cad emy 01 Sc ienc es , Be iJl ng, 1000 2 9, China, " Instl tu te 01 G eograph y, Ru ss ian A cad emy 01 Sc ien ces , M osco..., 1190 17, RUSS ld, ' D epartment 01 EiI" th and Spac e Sc ien ces , Un lvers lty 01 W as hing ton, Seattl e, W as hing t on 9819 5, USA , "' Natlona l Ce ntre 10r A nt il" ctic an d Ocean Researc h, Goa , 40 3 80 4 , India, " Labor at ory 01 Tree -R ing Rese arc h, Un ive r sity 01 A rilona, Tuc son, A rilona 8 5721 , USA , " Depar tm ent 01 Biology, Gh en t Un ive rs lty, Ghent, 9000 , Belgi um , "D epar tm ent 01 Geogr cp hy, Un ive r sity 01 ottaw a, ott im a, K1N 6N5, Cifl ada , ' 'N iels Bohr In s utut e, Ul ive rs lty 01 Cop enh age n, Cope nh age n, 21 00 , Denm ark, " In stl tut e l or Coas t al Researc h, H elmh u tl-Zentrum Gee sth ao::: ht , Gees th ac h t, 215 0 2, Germany, ' ''Na tiona l Cll m atic Data Ce n ter, N a ~ o n a l O ceanic and Atmosph eric A dm ln lstration , Bo ulder , Cuorado 80 30 5, US A , "'In sil tu t e 01 A rct lc ifl d A lp ne Rese arc h, Un ive rs lty 01 Co lorado , Boo lder , Cuorado 80 309 , USA , " Depar tm ent 01 Forest Sc ience, Shlnshu Un iv ersity, Nag ano, 399 - 4 598 , Japan. lD eceas ed .e -m all: Darrell. Ka u1m an o nau.edu ", NATUREGEOSOENCE I \.U 61 1o.tAY 2013 I ...w .....nJtur HOO1/ nJtu regi'OSC il'l1c . ~r 2013 Maar ill an Pub li sll ers li rr it ed. AII rigilt s re",rv ed Continental- scale temperature variabilit y during the pa st t wo millennia PAG ES 2k Co nso rtium NI/ture Geo!cierlce 6, 339- 346 (2013); publ ¡;;hed on] ¡ne 2 [ April 2013: corrt:'Cled after prirt 26 ApriJ 2013. m. 1n 1he wrsion uf Ihis Progress ArI icle originally pubi;;Jlell l he horsh~) pseudonym was incorrt:'Clly ~ aled as 1he PAGES lk Network. lhe currte'Cl Ilnllle is lllO' PAGES 2k Consorl iulll, rderring lo a grot ~) uf hors (f mm wilhin 1he more e:l.1ensive PAGES 2k Net work) who len ~)()rariJy worked I()~i her fOf ¡he plllVOse uf producing 1his paperolhis h.1S l:een corrt'Cled in 1he POF and HTML wrsioJls. m. Continental- scale temperature variabilit y during the pa st t wo millennia PAG ES 2 k Co nso rtium MilI/re GeO!ciellce 6, 339- 346 (20 13): published online 2 [ April 2013: com:'Cled after prinl [4 May 20 13. In 1he wrsioll ofthis Progress Anide originalJy publis,hed, lhe rderences "43- 54" ciled in "43- 45". lhis has been com:'Cled in Ihe POF and HTML wrsions. 11~ C~)li()n uf Fig. 4a sllOl~d haw read