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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
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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
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PROG RESS ARTICLE
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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"
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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
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2013 Maar ill an Pub li sllers li rr it ed . AII rig llt s re",rv ed
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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
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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"
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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
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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"
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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
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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
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Continental- scale temperature variabilit y during the pa st t wo millennia
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MilI/re GeO!ciellce 6, 339- 346 (20 13): published online 2 [ April 2013: com:'Cled after prinl [4 May 20 13.
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