{"id":3741,"date":"2015-01-03T08:52:34","date_gmt":"2015-01-03T08:52:34","guid":{"rendered":"http:\/\/www.agust.net\/wordpress\/?p=3741"},"modified":"2024-10-29T16:11:15","modified_gmt":"2024-10-29T16:11:15","slug":"loftslagsbreytingar-af-voldum-manna-eda-natturu","status":"publish","type":"post","link":"http:\/\/www.agust.net\/wordpress\/2015\/01\/03\/loftslagsbreytingar-af-voldum-manna-eda-natturu\/","title":{"rendered":"Loftslagsbreytingar af v\u00f6ldum manna e\u00f0a n\u00e1tt\u00faru?"},"content":{"rendered":"

\u00a0>>> Cum Grano Salis <<<<\/span>
\n<\/span><\/em><\/span><\/h2>\n

\n<\/span><\/em><\/span>D R \u00d6 G \u00a0 \u00cd \u00a0 V I N N S L U<\/span>\u00a0 \u00a0 –\u00a0 \u00a0(Upphaflega 2015<\/strong>, s\u00ed\u00f0ast breytt<\/strong>\u00a029\/10\/2024<\/b>).
\n\u00deessi vefs\u00ed\u00f0a er s\u00edfellt \u00ed vinnslu me\u00f0 n\u00fdju e\u00f0a breyttu efni.<\/em><\/span><\/h6>\n

(Ne\u00f0anm\u00e1ls eru nokkur vi\u00f0t\u00f6l vi\u00f0, e\u00f0a greinar eftir 8<\/span>
\n\u00feekkta \u00edslenska ve\u00f0urfr\u00e6\u00f0inga sem birst hafa \u00ed dagbl\u00f6\u00f0um, svo og nokkur myndb\u00f6nd).<\/span><\/h3>\n

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H\u00f6fundur \u00feessarar vefs\u00ed\u00f0u er \u00c1g\u00fast H. Bjarnason rafmagnsverkfr\u00e6\u00f0ingur. Hann hefur lengi haft \u00e1huga \u00e1 alheiminum og \u00fear me\u00f0 breytilegri virkni s\u00f3lstjarna, \u00fear me\u00f0 tali\u00f0 okkar eigin S\u00f3l. \u00dea\u00f0 m\u00f3ta\u00f0i uppeldi hans a\u00f0 hafa fengi\u00f0 1954, \u00fe\u00e1 9 \u00e1ra, a\u00f0 sj\u00e1 <\/em>almyrkva \u00e1 s\u00f3l<\/a> fr\u00e1 V\u00edk \u00ed M\u00fdrdal \u00fe<\/em>ar sem hann s\u00e1st einna best. Fyrsta gervihn\u00f6ttinn, Sputnik 1<\/a>, s\u00e1 hann snemma morguns \u00far Nor\u00f0urm\u00fdrinni sk\u00f6mmu eftir a\u00f0 honum var skoti\u00f0 \u00e1 loft. \u00c1 menntask\u00f3la\u00e1runum var hann \u00e1 vegum Almannavarna vi\u00f0staddur 4 geimskot franskra v\u00edsindamanna<\/a> 1964 og 1965, og f\u00e9kk a\u00f0 sko\u00f0a t\u00e6ki og b\u00fana\u00f0. \u00c1 \u00e1runum 1964-1969 stunda\u00f0i \u00c1g\u00fast m\u00e6lingar \u00e1 brautum gervihnatta<\/a> fyrir The Royal Astronomical Society. Um svipa\u00f0 leyti s\u00e1 hann um vi\u00f0hald \u00e1 3 m\u00e6lit\u00e6kjum \u00ed Segulm\u00e6lingast\u00f6\u00f0inni Leirvogi<\/a>, e\u00f0a svok\u00f6llu\u00f0um RIOMETER (Relative Ionospheric Opacity Meter for Extra-Terrestrial Emissions of Radio noise) sem reknir voru af The National Bureao of Standards, Boulder Colorado o.fl. Sumarstarfsma\u00f0ur \u00e1 H\u00e1loftadeild Raunv\u00edsindastofnunar H\u00e1sk\u00f3la \u00cdslands 1969 og 1970. \u00c1g\u00fast var \u00ed stj\u00f3rn Stj\u00f6rnusko\u00f0unarf\u00e9lagsins<\/a> um s\u00ed\u00f0ustu aldam\u00f3t. \u00c1g\u00fast hefur lengi haft \u00e1huga \u00e1 \u00e1hrifum s\u00f3lar \u00e1 j\u00f3nahvolf jar\u00f0ar sem m\u00f3tast af breytingum \u00ed virkni s\u00f3lar, en \u00feessar breytingar hafa veruleg \u00e1hrif \u00e1 \u00fatbrei\u00f0slu rad\u00ed\u00f3bylgna \u00e1 stuttbylgjusvi\u00f0inu. \u00cd starfi sem rafmagnsverkfr\u00e6\u00f0ingur hefur \u00c1g\u00fast komi\u00f0 a\u00f0 h\u00f6nnun stj\u00f3rn- og g\u00e6slukerfa allra virkjana \u00e1 Su\u00f0urnesjum og hefur mikla reynslu af m\u00e6lit\u00e6kni og mati \u00e1 skekkjuv\u00f6ldum, og \u00fear me\u00f0 mati \u00e1 m\u00e6li\u00f3vissu.<\/em><\/span><\/p>\n

Allt \u00feetta hefur vafal\u00edti\u00f0 beint sj\u00f3num h\u00f6fundar a\u00f0 m\u00f6gulegum \u00e1hrifum n\u00e1tt\u00farulegra breytinga \u00e1 ve\u00f0urfar jar\u00f0ar, n\u00fa sem \u00e1 \u00f6ldum \u00e1\u00f0ur.<\/em><\/span><\/p>\n

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\n0. Inngangur<\/span><\/strong><\/p>\n

1. Hitafar fr\u00e1 s\u00ed\u00f0ustu \u00eds\u00f6ld fyrir um 11.000 \u00e1rum<\/strong><\/span><\/p>\n

2. Breytingar s\u00ed\u00f0an \u00cdsland var numi\u00f0<\/strong><\/span><\/p>\n

3. Hl\u00fdnun s\u00ed\u00f0astli\u00f0in 150 \u00e1r fr\u00e1 Litlu \u00eds\u00f6ldinni<\/strong><\/span><\/p>\n

4. Hl\u00fdnun undanfarinna \u00e1ra<\/strong><\/span><\/p>\n

5. \u00c1st\u00e6\u00f0ur loftslagsbreytinga og hva\u00f0 er \u00feetta \u00abeitthva\u00f0\u00bb sem minnst var \u00e1 \u00ed innganginum?<\/strong><\/span><\/p>\n

6. \u00c1hrif aukningar CO2<\/strong><\/span><\/p>\n

7. Samantekt<\/strong><\/span><\/p>\n

8. Vi\u00f0auki <\/strong>(\u00deekktir \u00edslenskir ve\u00f0urfr\u00e6\u00f0ingar og v\u00edsindamenn hafa or\u00f0i\u00f0)<\/span><\/p>\n

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0. Inngangur<\/strong><\/span><\/h2>\n

1) Reglubundnar m\u00e6lingar \u00e1 lofthita h\u00f3fust um 1860. S\u00ed\u00f0an hefur hl\u00fdna\u00f0 um \u00fev\u00ed sem n\u00e6st 1,0 gr\u00e1\u00f0u Celcius a\u00f0 me\u00f0altali, sums sta\u00f0ar minna og sums sta\u00f0ar meira.\u00a0 \u00dea\u00f0 er almennt vi\u00f0urkennt og ver\u00f0ur ekki \u00e1 m\u00f3ti m\u00e6lt. \u00cd upphafi m\u00e6linga og jafnvel til 1920 st\u00f3\u00f0 yfir kuldat\u00edmabili\u00f0 sem vi\u00f0 k\u00f6llum “Litlu \u00eds\u00f6ldina”.<\/span><\/h3>\n

2) Styrkur koltv\u00eds\u00fdrings \u00ed andr\u00famloftinu hefur veri\u00f0 m\u00e6ldur reglubundi\u00f0 fr\u00e1 1958 og hefur styrkur hans aukist fr\u00e1 316 til 410 ppm, e\u00f0a fr\u00e1 0,032% til 0,041% \u00e1 t\u00edmabilinu, sem jafngildir 1 sameind af 10.000 sameindum loftsins. \u00dea\u00f0 er sta\u00f0reynd sem ekki ver\u00f0ur \u00e1 m\u00f3ti m\u00e6lt.\u00a0<\/span><\/h3>\n

3) Skrifast \u00f6ll h\u00e6kkun me\u00f0alhita jar\u00f0ar (~1\u00b0C) fr\u00e1 s\u00ed\u00f0ustu \u00e1ratugum Litlu \u00edsaldarinnar \u00e1 aukningu koltv\u00eds\u00fdrings \u00ed andr\u00famsloftinu, e\u00f0a skrifast hluti h\u00e6kkunarinnar \u00e1 n\u00e1tt\u00farulegar sveiflur? Ef svo er, a\u00f0 hve miklu leyti? Um \u00feetta eru menn ekki samm\u00e1la og svokalla\u00f0ir efasemdarmenn telja a\u00f0 \u00e1hrif n\u00e1tt\u00farunnar hafi veri\u00f0 vanmetin.<\/span><\/h3>\n

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Pistillinn fjallar um li\u00f0 3), enda flestir samm\u00e1la um li\u00f0i 1) og 2).<\/span><\/strong><\/p>\n

\u00cd lok pistilsins er \u00e1lit \u00feess er er \u00feennan pistil ritar, og \u00fear fyrir ne\u00f0an nokkrar bla\u00f0a\u00farklippur \u00fear sem sj\u00f3narmi\u00f0 nokkurra \u00edslenskra v\u00edsindamanna koma fram. Einnig m\u00e1 v\u00edsa \u00e1 pistil \u00fear sem fram kemur \u00e1lit pistilsh\u00f6fundar allt fr\u00e1 \u00e1rinu 1998, sj\u00e1 h\u00e9r<\/a>.<\/p>\n

… En n\u00f3g um \u00fea\u00f0.\u00a0 \u00a0Sn\u00faum okkur a\u00f0 efninu sem fjallar um \u00e1hrif koltv\u00eds\u00fdrings og n\u00e1tt\u00farulegra sveiflna \u00e1 hitafar jar\u00f0ar. Ne\u00f0anm\u00e1ls eru nokkrar \u00farklippur me\u00f0 umm\u00e6lum \u00edslenskra ve\u00f0urfr\u00e6\u00f0inga.<\/strong><\/em><\/p>\n

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Mynd 0: Loftslagskerfi\u00f0 er gr\u00ed\u00f0arlega fl\u00f3ki\u00f0 samspil margra \u00fe\u00e1tta. Styrkur koltv\u00eds\u00fdrings er einn \u00feessara \u00fe\u00e1tta, en l\u00edtill \u00ed samanbur\u00f0i vi\u00f0 a\u00f0ra eins og \u00feessi mynd minnir okkur \u00e1.\u00a0 \u00a0Hin almenna sk\u00fdring \u00e1 hl\u00fdnun lofthj\u00fapsins af v\u00f6ldum koltv\u00edsyrings er allt of mikil einf\u00f6ldun. M\u00e1li\u00f0 er fl\u00f3knara en \u00fea\u00f0.\u00a0 \u00a0\u00dea\u00f0 er ekki \u00far vegi a\u00f0 v\u00edsa h\u00e9r \u00e1 erindi sem Dr. Richard Lindz\u00e9n pr\u00f3fessor emeritus vi\u00f0 MIT h\u00e9lt fyrir sk\u00f6mmu og nefnist: Global Warming for the two Cultures<\/a>.<\/span><\/p><\/div>\n

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Umr\u00e6\u00f0ur um losun koltv\u00eds\u00fdrings (kols\u00fdru – CO2<\/sub>) af mannav\u00f6ldum hafa vaki\u00f0 \u00e1huga margra \u00e1 a\u00f0 kynna s\u00e9r \u00e1st\u00e6\u00f0ur ve\u00f0urfarsbreytinga \u00ed n\u00fat\u00ed\u00f0 og fort\u00ed\u00f0. Miklar breytingar \u00e1 ve\u00f0urfari hafa or\u00f0i\u00f0 a\u00f0 \u00fev\u00ed er vir\u00f0ist “af sj\u00e1lfu s\u00e9r” s\u00e9 liti\u00f0 hundru\u00f0 e\u00f0a \u00fe\u00fasundir \u00e1ra aftur \u00ed t\u00edmann. \u00a0Au\u00f0vita\u00f0 gerist sl\u00edkt ekki af sj\u00e1lfu s\u00e9r, eitthva\u00f0 hl\u00fdtur a\u00f0 koma ferlinu af sta\u00f0. Getur veri\u00f0 a\u00f0 \u00feetta “eitthva\u00f0” s\u00e9 einnig a\u00f0 hafa \u00e1hrif \u00e1 ve\u00f0ri\u00f0 \u00e1 \u00feessari \u00f6ld?\u00a0 Hva\u00f0 er \u00feetta “eitthva\u00f0”? \u00a0Getum vi\u00f0 b\u00faist vi\u00f0 a\u00f0 \u00fea\u00f0 muni haga s\u00e9r \u00e1 sama h\u00e1tt og \u00fea\u00f0 hefur gert oft \u00e1\u00f0ur, \u00fe.e. komi\u00f0, staldra\u00f0 vi\u00f0 og horfi\u00f0 s\u00ed\u00f0an \u00e1 braut? \u00a0\u00a0Um \u00fea\u00f0 fjallar \u00feessi grein.<\/strong><\/em><\/span><\/p>\n

\u00c1\u00f0ur en vi\u00f0 fj\u00f6llum um \u00feetta dularfulla “eitthva\u00f0” er r\u00e9tt a\u00f0 sko\u00f0a n\u00e1nar hva\u00f0 hefur veri\u00f0 \u00e1 sey\u00f0i undanfarin \u00e1r\u00fe\u00fasund og jafnvel enn \u00ed dag.<\/span><\/p>\n

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1. Hitafar fr\u00e1 s\u00ed\u00f0ustu \u00eds\u00f6ld fyrir um 11.000 \u00e1rum<\/strong><\/span><\/h2>\n

Mynd 1a<\/strong> s\u00fdnir ni\u00f0urst\u00f6\u00f0ur m\u00e6linga \u00e1 \u00edskj\u00f6rnum fengnum \u00far r\u00famlega 3000 metra dj\u00fapri holu sem boru\u00f0 var \u00ed Gr\u00e6nlandsj\u00f6kul. Me\u00f0 ranns\u00f3knum \u00e1 magni samst\u00e6tna s\u00farefnis (oxygen isotopes) hefur veri\u00f0 h\u00e6gt a\u00f0 \u00e1\u00e6tla hitastig \u00e1 yfirbor\u00f0i j\u00f6kulsins \u00fe\u00fasundir \u00e1ra aftur \u00ed t\u00edma. \u00deessi ferill n\u00e6r yfir 11.000 \u00e1r, \u00fe.e. aftur til loka \u00edsaldar \u00feegar \u00feykk \u00edshella \u00feakti st\u00f3ran hluta jar\u00f0ar.<\/p>\n

Ferillinn n\u00e6r \u00fe\u00f3 af m\u00e6lit\u00e6knilegum \u00e1st\u00e6\u00f0um a\u00f0eins til \u00e1rsins 1854, en hefur veri\u00f0 mj\u00f6g lauslega framlengdur til dagsins \u00ed dag me\u00f0 striku\u00f0u l\u00ednunni lengst til h\u00e6gri. Um lengdina \u00e1 rau\u00f0a strikinu m\u00e1 deila, en hafa ver\u00f0ur \u00ed huga a\u00f0 upplausn bl\u00e1a ferilsins er a\u00f0eins \u00ed besta falli 10 \u00e1r, en beinna hitam\u00e6linga undanfarna h\u00e1lfa a\u00f0ra \u00f6ld er 1 \u00e1r.\u00a0 \u00dev\u00ed ver\u00f0um vi\u00f0 a\u00f0 mi\u00f0a lengd striksins vi\u00f0 10 \u00e1ra me\u00f0altal hitam\u00e6linga, \u00feannig a\u00f0 \u00fea\u00f0 ver\u00f0ur v\u00e6ntanlegra styttra en ef mi\u00f0a\u00f0 v\u00e6ri vi\u00f0 1 \u00e1rs upplausn.<\/p>\n

\"Mynd

Mynd 1a: Ni\u00f0urst\u00f6\u00f0ur m\u00e6linga \u00e1 \u00edskj\u00f6rnum fengnum \u00far r\u00famlega 3000 metra dj\u00fapri holu sem boru\u00f0 var \u00ed Gr\u00e6nlandsj\u00f6kul. Skammvinn hl\u00fdskei\u00f0 eru s\u00fdnd me\u00f0 gr\u00e6nu. Myndin er upphaflega fr\u00e1 vefs\u00ed\u00f0u Dr. Ole Humlum pr\u00f3fessors emeritus,\u00a0climate4you.com<\/a>, undirs\u00ed\u00f0a Global temperature<\/em>. Rau\u00f0a strikinu hefur veri\u00f0 b\u00e6tt vi\u00f0. Mikilv\u00e6gt er a\u00f0 sko\u00f0a sk\u00fdringar Ole Humlum vi\u00f0 myndina\u00a0h\u00e9r<\/a>. Hafa ver\u00f0ur \u00ed huga a\u00f0 upplausn ferilsins h\u00e9r fyrir ofan er \u00ed besta falli 10 \u00e1r, en hitaferlar m\u00e6linga undanfarinna \u00e1ratuga eru me\u00f0 eins \u00e1rs upplausn. Einst\u00f6k \u00f3venju hl\u00fd e\u00f0a k\u00f6ld \u00e1r sj\u00e1st \u00fev\u00ed ekki \u00e1 \u00feessum ferli.<\/span><\/p><\/div>\n

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Mynd 1b: Anna\u00f0 sj\u00f3narhorn \u00e1 ni\u00f0urst\u00f6\u00f0urnar fr\u00e1 Gr\u00e6nlandsj\u00f6kli. H\u00e9r n\u00e6r t\u00edmabili\u00f0 yfir 4.000 \u00e1r, en \u00e1 fyrri myndinni 11.000 \u00e1r. Ferillinn n\u00e6r \u00fev\u00ed sem n\u00e6st til \u00e1rsins 1950.\u00a0 \u00a0H\u00e9r er l\u00f3\u00f0r\u00e9tti \u00e1sinn vinstra megin kvar\u00f0a\u00f0ur sem fr\u00e1vik s\u00farefnis-18 sams\u00e6tna, en sem yfirbor\u00f0shiti \u00e1 toppi j\u00f6kulsins \u00e1 fyrri myndinni.<\/span><\/p><\/div>\n

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\u00c1leitnar spurningar vakna \u00feegar horft er \u00e1 \u00feessa mynd. <\/strong>Hl\u00fdindin fyrir 1000, 2000, 3000, o.fl. \u00e1rum voru \u00f6rugglega ekki af mannav\u00f6ldum. \u00deetta voru heitari t\u00edmabil en vi\u00f0 upplifum n\u00fa. Hvernig getum vi\u00f0 veri\u00f0 viss um a\u00f0 hl\u00fdindin n\u00fa stafi a\u00f0 mestu leyti af heg\u00f0un okkar? Getur ekki veri\u00f0 a\u00f0 n\u00faverandi g\u00f3\u00f0\u00e6ri \u00ed ve\u00f0urfari undanfari\u00f0 stafi af s\u00f6mu ors\u00f6kum og oft \u00e1\u00f0ur? Er ekki full \u00e1st\u00e6\u00f0a til a\u00f0 velta fyrir s\u00e9r hva\u00f0a n\u00e1tt\u00farulegu \u00e1st\u00e6\u00f0ur hafi valdi\u00f0 \u00feessum hitasveiflum \u00e1 undanf\u00f6rnum \u00e1r\u00fe\u00fasundum og hvort a\u00f0 n\u00e1tt\u00faran s\u00e9 ekki enn a\u00f0 verki?<\/p>\n

Minni okkar er stutt, og sj\u00e1lf skynjum vi\u00f0 ekki nema nokkra \u00e1ratugi til baka. Ef til vill er \u00fea\u00f0 \u00feess vegna sem menn hafa einbl\u00ednt \u00e1 gr\u00f3\u00f0urh\u00fasa\u00e1hrif vegna aukningar koltv\u00eds\u00fdrings \u00ed andr\u00famsloftinu. \u00deessi kenning hefur veri\u00f0 mj\u00f6g vins\u00e6l, \u00fea\u00f0 vins\u00e6l a\u00f0 ekki hefur veri\u00f0 hlusta\u00f0 n\u00e6gilega vel \u00e1 gagnr\u00fdni sem komi\u00f0 hefur fram fr\u00e1 virtum v\u00edsindam\u00f6nnum \u00ed loftslagsfr\u00e6\u00f0um og stjarne\u00f0lisfr\u00e6\u00f0i sem telja a\u00f0 n\u00e1tt\u00faran eigi st\u00f3ran \u00fe\u00e1tt \u00ed breytingum, n\u00fa sem \u00e1 \u00f6ldum \u00e1\u00f0ur.<\/p>\n

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2. Breytingar s\u00ed\u00f0an \u00cdsland var numi\u00f0<\/strong><\/span><\/h2>\n
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Mynd 2a:\u00a0 \u00cdsland fyrir um \u00e1r\u00fe\u00fasundi…<\/span>
\u00dar b\u00f3kinni J\u00f6klar \u00e1 \u00cdslandi, eftir Dr. Helga Bj\u00f6rnsson, 2009.<\/span><\/p><\/div>\n

\u00cd gl\u00e6silegri b\u00f3k Dr. Helga Bj\u00f6rnssonar j\u00f6klafr\u00e6\u00f0ings, J\u00f6klar \u00e1 \u00cdslandi<\/strong><\/a>, sem kom \u00fat \u00e1ri\u00f0 2009, er mikill fr\u00f3\u00f0leikur um breytingar sem \u00e1tt hafa s\u00e9r sta\u00f0 \u00e1 \u00cdslandi. \u00a0B\u00f3kin fjallar, eins og nafni\u00f0 bendir til, fyrst og fremst um j\u00f6kla, en st\u00e6r\u00f0 \u00feeirra r\u00e6\u00f0st \u00ed a\u00f0alatri\u00f0um af \u00e1ratuga l\u00f6ngu \u00e1rfer\u00f0i. \u00a0\u00dea\u00f0 er \u00fev\u00ed \u00f3rofa samband milli hitafarsins og st\u00e6r\u00f0ar j\u00f6klanna. \u00deegar mildir \u00e1ratugir koma dragast \u00feeir saman, en ganga fram \u00e1\u00a0k\u00f6ldum \u00e1ratugum.<\/p>\n

Loftslag og j\u00f6klar \u00e1 s\u00ed\u00f0asta \u00e1r\u00fe\u00fasundi,<\/strong> er fyrirs\u00f6gn kafla \u00ed b\u00f3kinni sem Mynd 2a<\/em><\/strong>\u00a0 til hli\u00f0ar hefur veri\u00f0 fengin a\u00f0 l\u00e1ni \u00far. \u00dear kemur fram a\u00f0 loftslag hafi veri\u00f0 milt \u00e1 fyrstu \u00e1rum \u00cdslandbygg\u00f0ar, landi\u00f0 veri\u00f0 a\u00f0 miklu leyti gr\u00f3i\u00f0 og helmingur sk\u00f3gi vaxinn. Haf\u00eds\u00e1r sjaldg\u00e6f og j\u00f6klar minni en \u00ed dag. Mikil umfer\u00f0 hafi veri\u00f0 um h\u00e1lendi\u00f0 \u00e1 \u00feessum t\u00edma.<\/p>\n

Mynd 2b<\/strong> h\u00e9r fyrir ne\u00f0an me\u00f0 fyrirs\u00f6gninni Hl\u00fdtt var \u00e1 \u00cdslandi \u00e1 landn\u00e1ms- og \u00fej\u00f3\u00f0veldis\u00f6ld<\/strong> tengir saman breytingar \u00e1 hitastigi \u00e1 Gr\u00e6nlandsj\u00f6kli\u00a0(svartur ferill) og samsvarandi breytingar \u00e1 \u00cdslandi (hv\u00edtur ferill). Sj\u00e1 n\u00e1nar \u00ed sk\u00fdringum er fylgja myndinni.<\/p>\n

\u00deessi milda ve\u00f0r\u00e1tta st\u00f3\u00f0 til um 1200, en \u00fe\u00e1 f\u00f3r a\u00f0 k\u00f3lna. Hin svokalla\u00f0a Litla \u00eds\u00f6ld t\u00f3k vi\u00f0 og st\u00f3\u00f0 allt til \u00e1rsins 1900, e\u00f0a svo. J\u00f6klar gengu fram, haf\u00eds vi\u00f0 landi\u00f0 var\u00f0 stundum \u00e1rviss, gr\u00f3\u00f0ri hraka\u00f0i, hungur og vosb\u00fa\u00f0 hrj\u00e1\u00f0i f\u00f3lk og f\u00e9na\u00f0. Um 1920 f\u00f3r aftur a\u00f0 hl\u00fdna og stendur s\u00fa hl\u00fdnun enn yfir.<\/p>\n

Hvers vegna var hl\u00fdna\u00f0i svona fyrir \u00e1r\u00fe\u00fasundi? Hvers vegna k\u00f3lna\u00f0i aftur \u00e1 t\u00edmum Litlu \u00cdsaldar, og hvers vegna t\u00f3k aftur a\u00f0 hl\u00fdna \u00ed byrjun 20. aldar?<\/p>\n

\u00deetta eru spurningar sem brenna \u00e1 v\u00f6rum \u00feeirra sem forvitnir eru og l\u00e1ta ekki einfaldar \u00fatsk\u00fdringar n\u00e6gja.<\/p>\n

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Mynd 2b: \u00cdsland fyrir um \u00e1r\u00fe\u00fasundi…<\/span>
\u00dar b\u00f3kinni J\u00f6klar \u00e1 \u00cdslandi, eftir Dr. Helga Bj\u00f6rnsson, 2009.<\/span><\/p><\/div>\n

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N\u00fa er ekki \u00far vegi a\u00f0 staldra vi\u00f0 og vitna \u00ed Konungs Skuggsj\u00e1<\/a>. \u00a0 \u00dear m\u00e1 lesa me\u00f0al annars:<\/p>\n

“…En annar hlutur er forvitni, \u00fev\u00ed a\u00f0 \u00fea\u00f0 er mannsins n\u00e1tt\u00fara<\/span>
\n a\u00f0 forvitna og sj\u00e1 \u00fe\u00e1 hluti, er honum eru sag\u00f0ir, og vita, hvort svo er, sem<\/span>
\n honum var sagt, e\u00f0a eigi”.<\/span><\/h3>\n

Vonandi er lesandinn forvitinn og k\u00fds a\u00f0 fylgja lei\u00f0s\u00f6gumanni lengra \u00e1lei\u00f0is…<\/p>\n

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Breytingar \u00ed ve\u00f0urfari \u00e1 s\u00ed\u00f0ustu \u00f6ldum eru vel \u00feekktar.<\/strong> Sj\u00e1 mynd 2d<\/strong>. Myndin er bygg\u00f0 \u00e1 ranns\u00f3knum Dr. Craig Loehle. \u00c1 landn\u00e1ms\u00f6ld var jafnvel hl\u00fdrra \u00e1 j\u00f6r\u00f0inni en \u00ed dag, \u00cdsland var \u00fe\u00e1 vi\u00f0i vaxi\u00f0 milli fjalls og fj\u00f6ru og v\u00ednvi\u00f0ur \u00f3x jafnvel \u00ed Englandi. \u00de\u00e1 voru hinir miklu landafundir norr\u00e6nna manna, sem ekki v\u00edlu\u00f0u fyrir s\u00e9r a\u00f0 sigla \u00ed opnum b\u00e1tum landa og heims\u00e1lfa \u00e1 milli. Leifur heppni Eir\u00edksson fann V\u00ednland \u00fear sem v\u00ednvi\u00f0ur \u00f3x. Eir\u00edkur rau\u00f0i stofna\u00f0i bygg\u00f0 \u00ed Gr\u00e6nlandi \u00e1ri\u00f0 985 er hann sigldi me\u00f0 25 skip \u00cdslendinga \u00feanga\u00f0. Fundist hafa merki um r\u00e6ktun korns<\/a> \u00fear og \u00f6lger\u00f0<\/a> \u00feessara norr\u00e6nu manna.<\/p>\n

Samkv\u00e6mt ranns\u00f3knum var haf\u00eds vi\u00f0 strendur landsins l\u00edtill \u00e1 fyrstu \u00e1rum \u00cdslandsbygg\u00f0ar, Fer s\u00ed\u00f0an a\u00f0 aukast eftir 1200 og s\u00ed\u00f0an verulega eftir 1600 og fram \u00e1 s\u00ed\u00f0ustu \u00f6ld. Hvernig stendur \u00e1 \u00feessum breytingum \u00ed haf\u00edsnum, landsins forna fjanda? Sj\u00e1 mynd 2c.<\/p>\n

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Mynd 2c: Haf\u00eds vi\u00f0 \u00cdsland fr\u00e1 \u00fev\u00ed er landi\u00f0 bygg\u00f0ist. \u00dar b\u00f3kinni \u201cClimate, History and The Modern World\u201d eftir HH Lamb.<\/span><\/p><\/div>\n

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Eftir um 1200 f\u00f3r heimurinn a\u00f0 k\u00f3lna. \u00de\u00e1 gekk \u00ed gar\u00f0 langt t\u00edmabil sem menn hafa nefnt “Litlu \u00eds\u00f6ldina”. Mikil har\u00f0indi ur\u00f0u \u00e1 \u00cdslandi, bygg\u00f0 norr\u00e6nna manna \u00ed Gr\u00e6nlandi lei\u00f0 undir lok og kuldinn var \u00fea\u00f0 mikill \u00ed Englandi a\u00f0 Thames lag\u00f0i sum \u00e1rin \u00e1 vetrum. \u00c1hrifa litlu \u00edsaldarinnar g\u00e6tti um allan heim n\u00e6stu aldirnar.<\/p>\n

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Mynd 2d: Hnattr\u00e6nar hitabreytingar s\u00ed\u00f0astli\u00f0in 2000 \u00e1r.<\/span><\/p><\/div>\n

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Gamla m\u00e1lverki\u00f0 \u00e1 mynd 2e<\/strong>\u00a0eftir Abraham Hondius og er fr\u00e1 1677. Horft er ni\u00f0ur eftir \u00e1nni \u00ed \u00e1tt a\u00f0 g\u00f6mlu Lund\u00fanarbr\u00fanni.\u00a0 Lengst til h\u00e6gri handan br\u00faarinnar er Southwark Cathedral, og \u00fear til vinstri s\u00e9st \u00ed turn St. Olave’s Church.<\/p>\n

Taki\u00f0 eftir \u00edsj\u00f6kunum, sem vir\u00f0ast um h\u00e1lfur annar metri \u00e1 \u00feykkt. Hvernig stendur \u00e1 \u00feessum \u00f3sk\u00f6pum? Eitt kaldasta t\u00edmabil Litlu \u00edsaldarinnar svok\u00f6llu\u00f0u st\u00f3\u00f0 yfir me\u00f0an virkni s\u00f3lar var \u00ed l\u00e1gmaki sem kallast Maunder minimum. \u00dea\u00f0 st\u00f3\u00f0 yfir um \u00fea\u00f0 bil fr\u00e1 1645 til 1715. \u00de\u00e1 s\u00e1ust varla s\u00f3lblettir n\u00e9 nor\u00f0urlj\u00f3s og fimbulkuldi r\u00edkt v\u00ed\u00f0a. M\u00e1lverki\u00f0 er fr\u00e1 \u00feessu kuldaskei\u00f0i.<\/p>\n

\"Mynd

Mynd 2e: Me\u00f0an \u00e1 litlu \u00eds\u00f6ldinni st\u00f3\u00f0 var \u00e1in Thames vi\u00f0 London oft \u00edsi l\u00f6g\u00f0.<\/span>
M\u00e1lverki\u00f0 er eftir Abraham Hondius (1630-1695). Museum of London. Fleiri myndir af “Frost Fairs” \u00e1 Thames eru til.<\/span>
Horft er ni\u00f0ur eftir \u00e1nni \u00ed \u00e1tt a\u00f0 g\u00f6mlu Lund\u00fanarbr\u00fanni. Lengst til h\u00e6gri handan br\u00faarinnar er Southwark Cathedral, og \u00fear til vinstri s\u00e9st \u00ed turn St. Olave’s Church.<\/span><\/p><\/div>\n

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Hvernig var \u00e1standi\u00f0 \u00e1 \u00cdslandi um \u00feetta leyti?<\/strong><\/p>\n

\u00de\u00f3r Jakobsson segir \u00feetta \u00ed erindi s\u00ednu “Um haf\u00eds fyrir Su\u00f0urlandi – fr\u00e1 landn\u00e1mi til \u00feessa dags<\/a>” sem finna m\u00e1 \u00e1 vef Ve\u00f0urstofunnar:<\/p>\n

“1695. \u00d3vanalega miklir haf\u00edsar. \u00cds rak um veturinn upp a\u00f0 Nor\u00f0urlandi og l\u00e1 hann fram um \u00feing, nor\u00f0anve\u00f0ur r\u00e1ku \u00edsinn austur fyrir og svo su\u00f0ur, var hann kominn fyrir \u00deorl\u00e1ksh\u00f6fn fyrir sumarm\u00e1l og sunnudaginn fyrstan \u00ed sumri (14. apr\u00edl) rak hann fyrir Reykjanes og Gar\u00f0 og inn \u00e1 fiskileitir Seltirninga og a\u00f0 lokum a\u00f0 Hvalseyjum og \u00ed H\u00edtar\u00f3s, f\u00f3r hann inn \u00e1 hverja v\u00edk. Haf\u00f0i \u00eds ei komi\u00f0 fyrir Su\u00f0urnes innan 80 \u00e1ra, \u00fe\u00f3tti \u00fev\u00ed m\u00f6rgum n\u00fdst\u00e1rlegt og undrum gegna um komu hans. \u00de\u00e1 m\u00e1tti ganga \u00e1 \u00edsum af Akranesi \u00ed H\u00f3lmakaupsta\u00f0 (Reykjav\u00edk) og var \u00edsinn \u00e1 Faxafl\u00f3a fram um vert\u00ed\u00f0arlok r\u00famlega, braut hann skip undan 6 m\u00f6nnum fyrir Gar\u00f0i, en \u00feeir gengu allir til lands”.<\/em><\/span><\/p>\n

Um 1900 fer heimurinn a\u00f0 hl\u00fdna \u00e1 n\u00fdjan leik og hefur s\u00fa \u00fer\u00f3un haldist til dagsins \u00ed dag, – me\u00f0 rykkjum \u00fe\u00f3. Vi\u00f0 vitum hvernig \u00e1standi\u00f0 var h\u00e9r \u00e1 landi seint \u00e1 19. \u00f6ld \u00feegar vesturfer\u00f0ir \u00cdslendinga st\u00f3\u00f0u sem h\u00e6st, og f\u00f3lk fl\u00fa\u00f0i har\u00f0indi og f\u00e1t\u00e6kt sem af \u00fev\u00ed leiddi. Vi\u00f0 h\u00f6fum heyrt af frostavetrinum mikla 1918, s\u00ed\u00f0an komu veruleg hl\u00fdindi fram a\u00f0 str\u00ed\u00f0s\u00e1rum, \u00fe\u00e1 nokkur k\u00f3lnun fram til um 1975 er fer a\u00f0 hl\u00fdna aftur. Auk \u00feessara breytinga eru sm\u00e1 sveiflur fr\u00e1 \u00e1ri til \u00e1rs, sem eru breytilegar fr\u00e1 einu landi til annars, eins og vi\u00f0 k\u00f6nnumst vi\u00f0. H\u00e9r \u00e1 nor\u00f0ursl\u00f3\u00f0um, \u00fear sem me\u00f0alhiti \u00e1rsins er ekki nema nokkrar gr\u00e1\u00f0ur yfir frostmarki, erum vi\u00f0 miklu n\u00e6mari fyrir sm\u00e1v\u00e6gilegum hitafarsbreytingum en sunnar \u00ed \u00e1lfunni \u00fear sem \u00e1rsme\u00f0alhitinn er mun h\u00e6rri.<\/p>\n

Hven\u00e6r lauk Litlu \u00eds\u00f6ldinni? Um \u00fea\u00f0 m\u00e1 deila, sumir mi\u00f0a vi\u00f0 \u00e1ri\u00f0 1900 og enn a\u00f0rir vilja meina a\u00f0 frostaveturinn 1918 hafi veri\u00f0 dau\u00f0akippir \u00feessa langa kuldaskei\u00f0s.<\/p>\n

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Hinir s\u00edbreytilegu j\u00f6klar…<\/strong><\/p>\n

Kortin, 2f og 2g,\u00a0 h\u00e9r fyrir ne\u00f0an eru fengin a\u00f0 l\u00e1ni \u00far\u00a0\u00c1rb\u00f3k Landgr\u00e6\u00f0slu r\u00edkisins 1995-1997<\/strong>. \u00deau eru eftir jar\u00f0fr\u00e6\u00f0ingana Gr\u00e9tar Gu\u00f0bergsson<\/strong> og \u00deorleif Einarsson<\/strong>. \u00a0Kortin hafa veri\u00f0 ger\u00f0 til a\u00f0 gefa hugmynd um sennilega st\u00e6r\u00f0 j\u00f6kla mi\u00f0a\u00f0 vi\u00f0 st\u00e6r\u00f0 \u00feeirra n\u00fa \u00e1 t\u00edmum, en n\u00faverandi st\u00e6r\u00f0 er s\u00fdnd \u00e1 kortunum. \u00dea\u00f0 ver\u00f0ur \u00fev\u00ed a\u00f0 r\u00fdna kortin \u00ed \u00fev\u00ed lj\u00f3si og for\u00f0ast a\u00f0 sko\u00f0a sm\u00e1atri\u00f0i.<\/p>\n

Sk\u00fdringartextinn fyrir ne\u00f0an kortin fylgdi \u00feeim \u00ed \u00c1rb\u00f3kinni.<\/p>\n

Mynd 2f: Sennileg st\u00e6r\u00f0 j\u00f6kla vi\u00f0 Landn\u00e1m.<\/span>
Svartar \u00fatl\u00ednur s\u00fdna st\u00e6r\u00f0 j\u00f6klanna er myndin var teiknu\u00f0. Sj\u00e1 \u00c1rb\u00f3k Landgr\u00e6\u00f0slu r\u00edkisins 1995-1997<\/span>.<\/p><\/div>\n

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Mynd 2g: Sennileg st\u00e6r\u00f0 j\u00f6kla fyrir 2500 \u00e1rum.<\/span>
Svartar \u00fatl\u00ednur s\u00fdna st\u00e6r\u00f0 j\u00f6klanna er myndin var teiknu\u00f0. Sj\u00e1 \u00c1rb\u00f3k Landgr\u00e6\u00f0slu r\u00edkisins 1995-1997<\/span>.<\/p><\/div>\n

<\/h2>\n

Hj\u00f6rleifur Guttormsson:
\n<\/strong>\u201e\u00c1 landn\u00e1ms\u00f6ld og fram eftir \u00f6ldum voru j\u00f6klar h\u00e9r sem annars<\/span>
\nsta\u00f0ar \u00e1 landinu langtum minni en n\u00fa er. J\u00f6kulhetta var \u00e1<\/span>
\nHnappafelli, eins og \u00d6r\u00e6faj\u00f6kull var nefndur \u00ed \u00f6ndver\u00f0u, og<\/span>
\nskri\u00f0j\u00f6klar teyg\u00f0u sig \u00fear eitthva\u00f0 ni\u00f0ur eftir hl\u00ed\u00f0um. Vatnaj\u00f6kull<\/span>
\nvar til en langtum minni en s\u00ed\u00f0ar var\u00f0, hugsanlega a\u00f0 mestu skorinn<\/span>
\nsundur \u00ed tvo e\u00f0a \u00ferj\u00e1 j\u00f6kulskildi, enda lengst af kalla\u00f0ur<\/span>
\nKlofaj\u00f6kull. Meginskri\u00f0j\u00f6klarnir fr\u00e1 honum voru litlir \u00ed samanbur\u00f0i<\/span>
\nvi\u00f0 \u00fea\u00f0 sem s\u00ed\u00f0ar var\u00f0. \u00dea\u00f0 sem vi\u00f0 k\u00f6llum einu nafni<\/span>
\nBrei\u00f0amerkurj\u00f6kul voru \u00ferj\u00e1r skri\u00f0j\u00f6kultungur sem \u00f3v\u00edst er<\/span>
\nhvort n\u00e1\u00f0u a\u00f0 renna saman ne\u00f0an vi\u00f0 M\u00e1vabygg\u00f0ir en s\u00fa nafngift<\/span>
\nn\u00e1\u00f0i \u00fe\u00e1 einnig yfir Esjufj\u00f6ll. J\u00f6kulja\u00f0arinn hefur \u00fe\u00e1 legi\u00f0 allt<\/span>
\na\u00f0 15 k\u00edl\u00f3metrum innar en n\u00fa er en utan vi\u00f0 var sl\u00e9tta sem veri\u00f0<\/span>
\nhaf\u00f0i sj\u00e1varbotn \u00ed \u00edsaldarlokin. Drj\u00fagur hluti \u00feessarar miklu<\/span>
\nsl\u00e9ttu hefur veri\u00f0 gr\u00f3inn og sk\u00f3givaxinn \u00e1 k\u00f6flum eins og m\u00falarnir<\/span>
\nbeggja vegna og \u00fear var v\u00ed\u00f0a all\u00feykkur jar\u00f0vegur.\u201c<\/span><\/p>\n

— \u00c1rb\u00f3k Fer\u00f0af\u00e9lags \u00cdslands1993. Hj\u00f6rleifur Guttormsson.<\/span><\/em><\/p>\n

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\u00cd gl\u00e6silegri b\u00f3k Dr. Helga Bj\u00f6rnssonar j\u00f6klafr\u00e6\u00f0ings,<\/strong> J\u00f6klar \u00e1 \u00cdslandi<\/strong><\/a>, sem kom \u00fat \u00e1ri\u00f0 2009, er mikill fr\u00f3\u00f0leikur um breytingar sem \u00e1tt hafa s\u00e9r sta\u00f0 \u00e1 \u00cdslandi. \u00a0B\u00f3kin fjallar, eins og nafni\u00f0 bendir til, fyrst og fremst um j\u00f6kla, en st\u00e6r\u00f0 \u00feeirra r\u00e6\u00f0st \u00ed a\u00f0alatri\u00f0um af \u00e1ratuga l\u00f6ngu \u00e1rfer\u00f0i. \u00a0\u00dea\u00f0 er \u00fev\u00ed \u00f3rofa samband milli hitafarsins og st\u00e6r\u00f0ar j\u00f6klanna. \u00deegar mildir \u00e1ratugir koma dragast \u00feeir saman, en ganga fram \u00e1\u00a0k\u00f6ldum \u00e1ratugum.<\/p>\n

Kortin h\u00e9r fyrir eru fengin a\u00f0 l\u00e1ni \u00far b\u00f3kinni ne\u00f0an s\u00fdna umfang Vatnaj\u00f6kuls fyrir 4000 \u00e1rum, 3000 \u00e1rum, 2000 \u00e1rum og 1000 \u00e1rum. Allar \u00feessar breytingar eiga s\u00e9r n\u00e1tt\u00farulegar sk\u00fdringar.<\/p>\n

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Mynd 2h: \u00dar b\u00f3k Helga Bj\u00f6rnssonar j\u00f6klafr\u00e6\u00f0ings, J\u00f6klar \u00e1 \u00cdslandi.<\/span><\/p><\/div>\n

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Mynd 2i: \u00dar b\u00f3k Helga Bj\u00f6rnssonar j\u00f6klafr\u00e6\u00f0ings, J\u00f6klar \u00e1 \u00cdslandi.\u00a0 \u00a0Kortin\u00a0 s\u00fdna umfang Vatnaj\u00f6kuls fyrir 4000 \u00e1rum, 3000 \u00e1rum, 2000 \u00e1rum og 1000 \u00e1rum. Allar \u00feessar breytingar eiga s\u00e9r n\u00e1tt\u00farulegar sk\u00fdringar.\u00a0 Sj\u00e1 sk\u00fdringar h\u00e9r fyrir ofan og \u00ed texta sem fylgir kortunum.<\/span><\/p><\/div>\n

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Helgi Bj\u00f6rnsson<\/strong> j\u00f6klafr\u00e6\u00f0ingur svarar spurningunni \u00a0 “Var einu sinni \u00edslaus dalur \u00ed mi\u00f0jum Vatnaj\u00f6kli?”<\/strong> \u00e1 V\u00edsindavefnum h\u00e9r<\/a>.<\/p>\n

—<\/p>\n

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Mynd 2j:\u00a0 \u00dar pistli P\u00e1ls Berg\u00fe\u00f3rssonar<\/strong> \u00e1 Fasb\u00f3k 25. \u00e1g\u00fast 2014<\/span><\/p><\/div>\n

.P\u00e1ll Berg\u00fe\u00f3rsson ve\u00f0urfr\u00e6\u00f0ingur<\/strong> skrifa\u00f0i vi\u00f0 myndina h\u00e9r a\u00f0 ofan 25. \u00e1g\u00fast 2014:<\/span><\/p>\n

“\u00deetta yfirlit yfir loftslag \u00e1 landinu ger\u00f0i \u00e9g fyrir m\u00f6rgum \u00e1rum, sveiflur, stuttar og langar. S\u00ed\u00f0an skipti \u00e9g \u00fev\u00ed \u00ed fj\u00f6gur t\u00edmabil me\u00f0 mismunandi me\u00f0alhita. S\u00ed\u00f0an f\u00e9kk \u00e9g athuganir fr\u00e1 Gr\u00e6nlandsj\u00f6kli um svonefndar s\u00farefnissams\u00e6tur, sem eru taldar gefa g\u00f3\u00f0ar v\u00edsbendingar um hitann. Samr\u00e6mi\u00f0 er b\u00fdsna gott og sty\u00f0ur \u00e1\u00e6tlanirnar um me\u00f0alhitann h\u00e9r. Ekki m\u00e1 \u00fe\u00f3 b\u00faast vi\u00f0 a\u00f0 styttri sveiflur s\u00e9u samt\u00ed\u00f0a, h\u00e9r getur \u00fe\u00e1 veri\u00f0 r\u00edkjandi su\u00f0l\u00e6g \u00e1tt \u00fe\u00f3 a\u00f0 \u00e1 Gr\u00e6nlandi s\u00e9 h\u00fan nor\u00f0l\u00e6g. En \u00e1 lengri t\u00edma jafnar \u00feetta sig upp.<\/span><\/p>\n

\u00c1berandi eru har\u00f0ar sveiflur og mikill kuldi fr\u00e1 \u00fev\u00ed fyrir 1600 og fram um 1920, oft har\u00f0indakaflar me\u00f0 h\u00e1lfrar aldar millibili og \u00fe\u00e1 var verulegt mannfall af skorti svo a\u00f0 nam \u00fe\u00fasundum. En \u00e1 s\u00ed\u00f0ari hluta 19. aldar var\u00f0 hungurdau\u00f0inn st\u00f3rum minni \u00fer\u00e1tt fyrir mikinn kulda, \u00fe\u00f3 a\u00f0 sums sta\u00f0ar yr\u00f0i hans vart. \u00dea\u00f0 m\u00e1 tr\u00falega \u00feakka \u00fev\u00ed a\u00f0 allt a\u00f0 \u00fev\u00ed 20% \u00fej\u00f3\u00f0arinnar fl\u00fa\u00f0i til Amer\u00edku, einkum \u00feeir f\u00e1t\u00e6kustu, og \u00feeir sem eftir ur\u00f0u \u00feurftu \u00fe\u00e1 ekki a\u00f0 taka eins mikinn \u00fe\u00e1tt \u00ed hj\u00e1lparstarfi. Langsamlega mestur var fl\u00f3ttinn einmitt fr\u00e1 k\u00f6ldustu sv\u00e6\u00f0unum austan til \u00e1 Nor\u00f0urlandi. \u00deetta rifjast upp vegna fyrsta sj\u00f3nvarps\u00fe\u00e1ttar Egils Helgasonar um vesturfer\u00f0irnar \u00ed g\u00e6rkv\u00f6ldi. – Ekki hefur \u00fearna veri\u00f0 b\u00e6tt vi\u00f0 s\u00ed\u00f0ustu sveiflum, me\u00f0 mestu hl\u00fdindi \u00ed 800 \u00e1r, einkum n\u00fa eftir aldam\u00f3tin, og tr\u00falega nokku\u00f0 svipa\u00f0 loftslag og \u00e1 fyrstu \u00feremur \u00f6ldum \u00cdslandsbygg\u00f0ar. En j\u00f6klarnir eru ekki or\u00f0nir eins litlir og \u00fe\u00e1, \u00fea\u00f0 tekur langan t\u00edma a\u00f0 br\u00e6\u00f0a \u00fe\u00e1”.<\/span><\/h3>\n

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Sj\u00e1 einnig greinina Loftslag \u00e1 \u00cdslandi og Gr\u00e6nlandi<\/a> eftir P\u00e1l Berg\u00fe\u00f3rsson.<\/strong><\/p>\n

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Haf\u00edsinn og S\u00f3lin . . .
\n<\/span><\/strong>
\nMerkileg grein \u00e1 vef D\u00f6nsku Ve\u00f0urstofunnar DMI<\/a>.<\/strong><\/span><\/p>\n

Fjalla\u00f0 er um haf\u00eds vi\u00f0 \u00cdsland fr\u00e1 1500 til 2000, og \u00ed lj\u00f3s kemur samsv\u00f6run vi\u00f0 lengd s\u00f3lsveiflunnar.<\/span>
\nHeildregna l\u00ednan er haf\u00eds vi\u00f0 \u00edsland, strika\u00f0a l\u00ednan lengd s\u00f3lsveiflunnar.<\/span><\/span><\/p>\n

Smella \u00e1 kr\u00e6kju til a\u00f0 sj\u00e1 greinina<\/span>.
\nhttp:\/\/www.dmi.dk\/fileadmin\/Rapporter\/SR\/sr05-02.pdf<\/a><\/p>\n

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\"\"

Mynd 2k:\u00a0 \u00a0 Haf\u00eds vi\u00f0 \u00cdsland fr\u00e1 1500 til 2000.\u00a0 Heildregna l\u00ednan er haf\u00eds vi\u00f0 \u00edsland, strika\u00f0a l\u00ednan er lengd s\u00f3lsveiflunnar. \u00a0Taki\u00f0 eftir samsv\u00f6run haf\u00edss vi\u00f0 lengd s\u00f3lsveiflunnar.<\/span><\/p><\/div>\n

<\/h3>\n

Mikilv\u00e6gar spurningar:<\/h3>\n

Var hl\u00fdja loftslagi\u00f0 \u00e1 mi\u00f0\u00f6ldum (Medieval Warm Period \u2013 MWP) hnattr\u00e6nt fyrirb\u00e6ri e\u00f0a bundi\u00f0 vi\u00f0 \u00e1kve\u00f0na sta\u00f0i \u00e1 j\u00f6r\u00f0inni?<\/strong><\/a><\/p>\n

(Smella \u00e1 fyrirs\u00f6gn til a\u00f0 sj\u00e1 greinina).<\/p>\n

Sj\u00e1 einnig:\u00a0 Medieval Warm Period Project<\/strong>\u00a0 http:\/\/www.co2science.org\/data\/mwp\/mwpp.php<\/a><\/p>\n

“Our Medieval Warm Period Project is an ongoing effort to document the magnitude and spatial and temporal distributions of a significant period of warmth that occurred approximately one thousand years ago. Its purpose is to ultimately determine if the Medieval Warm Period (1) was or was not global in extent, (2) was less warm than, equally as warm as, or even warmer than the Current Warm Period, and (3) was longer or shorter than the Current Warm Period has been to date . . .”<\/em><\/h6>\n

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<\/h4>\n

3. Hl\u00fdnun s\u00ed\u00f0astli\u00f0in 150 \u00e1r fr\u00e1 Litlu \u00eds\u00f6ldinni<\/strong><\/span><\/h2>\n

Samkv\u00e6mt m\u00e6lingum er tali\u00f0 a\u00f0 hitastig jar\u00f0ar hafi h\u00e6kka\u00f0 um \u00fev\u00ed sem n\u00e6st 0,8\u00b0C s\u00ed\u00f0an um 1850. Vi\u00f0 getum teygt \u00fea\u00f0 \u00ed 1\u00b0C ef vi\u00f0 teljum ve\u00f0urfyrirb\u00e6ri\u00f0 El-Nino me\u00f0.\u00a0 Hvers vegna 1850?\u00a0 J\u00fa \u00fea\u00f0 er vegna \u00feess a\u00f0 s\u00e6milega \u00e1rei\u00f0anlegar eldri m\u00e6lingar \u00e1 lofthita eru ekki til. \u00de\u00e1 var Litlu \u00eds\u00f6ldinni ekki loki\u00f0. Verulegur hluti \u00feessa t\u00edmabils, um \u00fea\u00f0 bil h\u00e1lf \u00f6ld, tilheyrir Litlu \u00eds\u00f6ldinni. Skekkir \u00fea\u00f0 ekki a\u00f0eins myndina?<\/p>\n

Menn hafa af \u00fev\u00ed miklar \u00e1hyggjur a\u00f0 me\u00f0alhiti jar\u00f0ar hafi h\u00e6kka\u00f0 um \u00fev\u00ed sem n\u00e6st 1 gr\u00e1\u00f0u \u00e1 150 \u00e1rum? Hver vill fullyr\u00f0a a\u00f0 um 1850, \u00e1 s\u00ed\u00f0ustu \u00e1ratugum Litlu \u00edsaldar, hafi ve\u00f0urfar veri\u00f0 \u201cr\u00e9tt\u201d og \u00f6ll h\u00e6kkun hita s\u00ed\u00f0an \u00fe\u00e1 s\u00e9 \u201cr\u00f6ng\u201d og h\u00e6ttuleg?\u00a0\u00a0 \u00dea\u00f0 merkilega er a\u00f0 \u00feetta er kjarninn \u00ed umr\u00e6\u00f0unni um loftslagsm\u00e1lin.<\/p>\n

Reyndar er \u00fea\u00f0 svo a\u00f0 h\u00e6kkun hitastigs er oft mi\u00f0u\u00f0 vi\u00f0 “t\u00edmabili\u00f0 fyrir i\u00f0nbyltingu”,\u00a0\u00a0en i\u00f0nbyltingin er almennt talin hafa hafist \u00e1 18. \u00f6ld, og stundum mi\u00f0a\u00a0sagnfr\u00e6\u00f0ingar<\/a>\u00a0vi\u00f0 \u00e1rtali\u00f0 \u00feegar James Watt endurb\u00e6tti gufuv\u00e9lina 1770 og\u00a0James Hargreaves fann upp spunav\u00e9lina 1764.\u00a0 \u00cd \u00feessu sambandi skiptir \u00fea\u00f0\u00a0ekki m\u00e1li, \u00fev\u00ed allt eru \u00feetta t\u00edmar sem tilheyra kuldat\u00edmabili Litlu \u00edsaldar.\u00a0\u00dea\u00f0 eru\u00a0einnig\u00a0skiptar sko\u00f0anir um \u00fea\u00f0 hven\u00e6r Litlu \u00eds\u00f6ldinni lauk. \u00a0 \u00cdslenskir j\u00f6klar gengu lengst fram \u00e1 t\u00edmabilinu 1890-1920, sj\u00e1\u00a0h\u00e9r<\/a>.\u00a0Sumir mi\u00f0a vi\u00f0 1850, en\u00a0a\u00f0rir ekki fyrr en 1920<\/a>)<\/p>\n

Vi\u00f0 sj\u00e1um greinilega \u00e1 hitaferlinum fr\u00e1 Bresku Ve\u00f0urstofunni (mynd 3a<\/strong>) a\u00f0 Litlu \u00cds\u00f6ldinni l\u00fdkur ekki endanlega fyrr en um 1920, \u00fe\u00e1 ver\u00f0ur mj\u00f6g hr\u00f6\u00f0 hl\u00fdnun fram a\u00f0 1945, s\u00ed\u00f0an kyrrsta\u00f0a til um 1980 er hitinn fer a\u00f0 r\u00edsa hratt til \u00e1rsins 2000, og a\u00f0 lokum meira og minna kyrrsta\u00f0a til dagsins \u00ed dag. Allra s\u00ed\u00f0ustu \u00e1r hefur \u00f6flugur hitatoppur sem kallast El-Nino sem stafar af ve\u00f0urfyrirb\u00e6ri \u00ed Kyrrahafinu villt m\u00f6nnum s\u00fdn, en hann s\u00e9st \u00e1 mynd 4.<\/p>\n

Eftirtektarvert er a\u00f0 \u00e1 t\u00edmabilinu 1920 til 1945 er \u00e1l\u00edka hr\u00f6\u00f0 og \u00e1l\u00edka mikil h\u00e6kkun \u00e1 hitastigi og \u00e1 t\u00edmabilinu 1975 til 2000. Hvort tveggja 25 \u00e1ra t\u00edmabil. \u00dea\u00f0 er umhugsunarvert a\u00f0 losun manna \u00e1 koltv\u00eds\u00fdringi var tilt\u00f6lulega l\u00edtil fyrr en eftir mi\u00f0ja s\u00ed\u00f0ustu \u00f6ld er losunin f\u00f3r hratt vaxandi. \u00dea\u00f0 fl\u00e6kir au\u00f0vita\u00f0 m\u00e1li\u00f0 d\u00e1l\u00edti\u00f0.\u00a0 Var \u00fea\u00f0 kannski n\u00e1tt\u00faran sem var a\u00f0 verki \u00e1 fyrra t\u00edmabilinu og mannf\u00f3lki\u00f0 \u00e1 hinu s\u00ed\u00f0ara?\u00a0 E\u00f0a \u00e1 n\u00e1tt\u00faran einhvern \u00fe\u00e1 \u00ed hitabreytingunum yfir allt t\u00edmabili\u00f0? \u00dea\u00f0 hefur h\u00fan alltaf gert.<\/p>\n

Vi\u00f0 t\u00f6kum eftir \u00fev\u00ed a\u00f0 me\u00f0alhitinn yfir allt t\u00edmabili\u00f0 er nokkurn vegin s\u00e1 sami og m\u00e6ldist \u00ed kyrrst\u00f6\u00f0unni 1945-1975. V\u00e6ri ekki e\u00f0lilegra a\u00f0 mi\u00f0a h\u00e6kkun lofthitans vi\u00f0 \u00fea\u00f0 t\u00edmabil frekar en Litlu \u00cds\u00f6ldina eins og gert er?\u00a0 \u00de\u00e1 v\u00e6ri h\u00e6kkunin sem vi\u00f0 v\u00e6rum me\u00f0 \u00e1hyggjur af um 0,5 gr\u00e1\u00f0ur \u00ed sta\u00f0 1 gr\u00e1\u00f0a. Varla hafa \u00fe\u00f3 n\u00e1tt\u00farulegar sveiflur h\u00e6tt um mi\u00f0ja s\u00ed\u00f0ustu \u00f6ld.<\/p>\n

Vi\u00f0 t\u00f6kum einnig eftir gr\u00e1u l\u00f3\u00f0r\u00e9ttu linunum sem ganga upp og ni\u00f0ur \u00far \u00f6llum m\u00e6lipunktunum. \u00deessar l\u00ednur t\u00e1kna \u00f3vissum\u00f6rk m\u00e6linganna.\u00a0 \u00deessi \u00f3vissum\u00f6rk eru +\/- 0,2 gr\u00e1\u00f0ur \u00e1 vinstri hluta ferilsins og +\/- 0,1 gr\u00e1\u00f0a \u00e1 h\u00e6gri hluta ferilsins. Til \u00feess ver\u00f0um vi\u00f0 au\u00f0vita\u00f0 a\u00f0 taka \u00feegar vi\u00f0 segjum h\u00e6kkun lofthita vera 1\u00b0C yfir allt t\u00edmabii\u00f0. Vi\u00f0 getum ekki fullyrt \u00fea\u00f0.<\/p>\n

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\"Mynd

Mynd 3a: Myndin er fr\u00e1 Bresku ve\u00f0urstofunni Met Office. H\u00fan s\u00fdnir fr\u00e1vik \u00ed me\u00f0alhita t\u00edmabilsins 1850 til 2013. \u00c1 \u00feessum t\u00edma hefur styrkur koltv\u00eds\u00fdrings aukist fr\u00e1 0,03% \u00ed 0,04%.\u00a0\u00a0<\/span><\/p><\/div>\n

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Mynd fr\u00e1 Bresku ve\u00f0urstofunni MetOffice. Gulu r\u00f6ndina hafa \u00feeir sett inn sem vi\u00f0mi\u00f0un um 1\u00b0 h\u00e6kkun fr\u00e1 \u00fev\u00ed \u201cfyrir i\u00f0nbyltingu\u201d<\/strong><\/span>
\nhttps:\/\/www.metoffice.gov.uk\/research\/news\/2018\/global-surface-temperatures-in-2017<\/a><\/p>\n

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\"Mynd

Mynd 3b: \u00d6nnur mynd fr\u00e1 Bresku ve\u00f0urstofunni Met Office. St\u00f3r hluti ferilsins tilheyrir Litlu \u00eds\u00f6ldinni, en n\u00e6r \u00fe\u00f3 ekki aftur til upphafs i\u00f0nbyltingar um 1750<\/span><\/p><\/div>\n

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<\/div>\n

4. Hl\u00fdnun undanfarinna \u00e1ra.<\/strong><\/span><\/h2>\n

N\u00e1tt\u00faran hefur veri\u00f0 a\u00f0 str\u00ed\u00f0a okkur fr\u00e1 aldam\u00f3tum, \u00fev\u00ed eitthva\u00f0 veldur \u00fev\u00ed a\u00f0 me\u00f0alhiti jar\u00f0ar hefur meira og minna sta\u00f0i\u00f0 \u00ed sta\u00f0 fr\u00e1 aldam\u00f3tum til \u00e1rsins 2015 eins og s\u00e9st \u00e1 mynd 4<\/strong>, \u00fer\u00e1tt fyrir s\u00edvaxandi losun manna \u00e1 koltv\u00eds\u00fdringi CO2. L\u00e1tum \u00fe\u00f3 ekki skammt\u00edma sveiflur \u00ed hitafari villa okkur s\u00fdn. Myndin s\u00fdnir b\u00e6\u00f0i gildi hvers m\u00e1na\u00f0ar og 37 m\u00e1na\u00f0a me\u00f0altal, sem er r\u00e9ttara a\u00f0 fylgjast me\u00f0 en skammt\u00edmasveiflum sem segja l\u00edti\u00f0.<\/p>\n

Hitam\u00e6lingar \u00e1 lofthj\u00fapnum fara \u00ed a\u00f0alatri\u00f0um fram \u00e1 tvennan h\u00e1tt: Me\u00f0 hef\u00f0bundnum hitam\u00e6lum \u00e1 ve\u00f0urst\u00f6\u00f0vum v\u00ed\u00f0a um heim og fr\u00e1 gervihn\u00f6ttum. M\u00e6lingar fr\u00e1 gervihn\u00f6ttum hafa \u00fea\u00f0 fram yfir kvikasilfursm\u00e6lana a\u00f0 gervihnettirnir m\u00e6la yfir allan hn\u00f6ttinn, bygg\u00f0 b\u00f3l, hafi\u00f0, ey\u00f0imerkur, fj\u00f6ll og firnindi. Svok\u00f6llu\u00f0 \u00fe\u00e9ttb\u00fdlis\u00e1hrif trufla ekki \u00fe\u00e6r m\u00e6lingar, en vi\u00f0 vitum flest hve miklu heitara er innan borgarmarkanna en utan \u00feeirra. \u00deessar m\u00e6lingar fr\u00e1 gervihn\u00f6ttum n\u00e1 \u00fe\u00f3 a\u00f0eins aftur til \u00e1rsins 1979. \u00c1 \u00feeim m\u00e1 greina \u00e1hrif fr\u00e1 st\u00f3rum eldgosum og fyrirb\u00e6rum \u00ed Kyrrahafinu sem k\u00f6llu\u00f0 eru El Ni\u00f1o og La Ni\u00f1a.<\/p>\n

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Mynd 4: Hitam\u00e6lingar fr\u00e1 gervihn\u00f6ttum s\u00fdna mest sveiflur fr\u00e1 s\u00ed\u00f0ustu aldam\u00f3tum. El-Nino topparnir \u00e1rin 1998 og 2015\/16 villa m\u00f6rgum s\u00fdn, en \u00fea\u00f0 eru ve\u00f0urfyrirb\u00e6ri \u00ed Kyrrahafinu sem koma loftslagsm\u00e1lum l\u00edti\u00f0 vi\u00f0. Myndin var uppf\u00e6r\u00f0 \u00ed mars 2019 og n\u00e6r ferillinn til loka okt\u00f3ber.<\/span><\/p><\/div>\n

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5. \u00c1st\u00e6\u00f0ur loftslagsbreytinga og hva\u00f0 er \u00feetta \u00abeitthva\u00f0\u00bb sem minnst var \u00e1 \u00ed innganginum?<\/strong><\/span><\/h2>\n

Lj\u00f3st er a\u00f0 \u00fdmislegt anna\u00f0 getur haft \u00e1hrif \u00e1 loftslagsbreytingar en koltv\u00eds\u00fdringur. Margir \u00feekkja snjallar kenningar hins virta v\u00edsindamanns P\u00e1ls Berg\u00fe\u00f3rssonar um samspil breytilegs endurskins fr\u00e1 haf\u00eds sem orsakavalds hinnar vel\u00feekktu 60 \u00e1ra sveiflu \u00ed hitafari. Margir beina sj\u00f3num a\u00f0 s\u00f3linni, okkar eina hitagjafa. \u00a0S\u00f3lin \u00e1 mynd 5a<\/strong> er svok\u00f6llu\u00f0 breytistjarna sem j\u00f6r\u00f0in er \u00ed n\u00e1b\u00fdli vi\u00f0. Fr\u00e1 henni streymir breytilegur s\u00f3lvindurinn sem veldur fallegum nor\u00f0urlj\u00f3sum, og g\u00e6ti \u00e1tt verulegan \u00fe\u00e1tt \u00ed hitasveiflum undanfarinna alda og \u00e1r\u00fe\u00fasunda samkv\u00e6mt vel\u00feekktum kenningum pr\u00f3fessors Henriks Svensmark<\/a>.<\/p>\n

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\"Mynd

Mynd 5a: S\u00f3lin er breytileg stjarna. Virkni hennar gengur \u00ed bylgjum. Sveiflurnar eru \u00e1ratuga, \u00e1rhundra\u00f0a og \u00e1r\u00fe\u00fasunda langar. J\u00f6r\u00f0in er \u00ed n\u00e1b\u00fdli vi\u00f0 \u00feessa dagstj\u00f6rnu.<\/span><\/p><\/div>\n

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\u00c1 mynd 5b<\/strong> m\u00e1 sj\u00e1 breytingar \u00ed heildar\u00fatgeislun s\u00f3lar fr\u00e1 \u00e1rinu 1610 til 2014. Eins og sj\u00e1 m\u00e1, \u00fe\u00e1 er h\u00fan \u00ed h\u00e6stu h\u00e6\u00f0um \u00e1 s\u00ed\u00f0arihluta n\u00fdli\u00f0innar aldar, og n\u00fa er heildar\u00fatgeislunin farin a\u00f0 dala aftur. Maunder l\u00e1gmarki\u00f0 fr\u00e1 1650-1700 leynir s\u00e9r ekki.<\/p>\n

Breytingin \u00ed heildar\u00fatgeislun er reyndar heldur l\u00edtil til a\u00f0 sk\u00fdra hitabreytingar undanfari\u00f0 \u00feannig a\u00f0 leita \u00fearf annarra sk\u00fdringa. Sk\u00fdringin g\u00e6ti legi\u00f0 \u00ed \u00fatfj\u00f3lubl\u00e1a \u00fe\u00e6tti s\u00f3larlj\u00f3ssins e\u00f0a s\u00f3lvindinum, og beinast augu v\u00edsindamanna n\u00fa a\u00f0 \u00feeim m\u00f6guleikum.<\/p>\n

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\"Mynd

Mynd 5b: Virkni s\u00f3lar s\u00ed\u00f0astli\u00f0in 400 \u00e1r.<\/strong> Heildar\u00fatgeislun s\u00f3lar<\/strong> (TSI, Total Solar Irradience \u00ed w\u00f6ttum \u00e1 fermetra) hefur aukist jafnt og \u00fe\u00e9tt s\u00ed\u00f0astli\u00f0in 400 \u00e1r \u00e1samt \u00fev\u00ed sem hnattr\u00e6n hl\u00fdnun hefur \u00e1tt s\u00e9r sta\u00f0 s\u00ed\u00f0ustu \u00f6ld.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0\u00a0 \u00dea\u00f0 er merkileg tilviljun hve vel \u00feessi ferill samsvarar breytingum \u00ed lofthita yfir sama t\u00edmabil.
\u00cd st\u00f3rum dr\u00e1ttum sj\u00e1um vi\u00f0 Maunder l\u00e1gmarki\u00f0 1650-1700 og kaldasta t\u00edmabil Litlu \u00edsaldar, Dalton l\u00e1gmarki\u00f0 \u00feegar hi\u00f0 fr\u00e6ga “year without a summer” var 1816 (reyndar mikil eldgos einnig \u00fe\u00e1), kuldaskei\u00f0 \u00feegar vesturfer\u00f0ir \u00cdslendinga st\u00f3\u00f0u sem h\u00e6st, og hl\u00fdindin fr\u00e1 mi\u00f0ri s\u00ed\u00f0ustu \u00f6ld. Allt saman au\u00f0vita\u00f0 tilviljun – e\u00f0a \u00feannig…\u00a0 \u00a0 \u00a0 Sj\u00e1 n\u00e1nar h\u00e9r var\u00f0andi \u00fatsk\u00fdringar og heimildir:\u00a0 https:\/\/www.climate4you.com\/Sun.htm<\/a><\/span><\/p><\/div>\n

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Mynd 5b1: Virkni s\u00f3lar fr\u00e1 \u00e1rinu 2003<\/strong>. Myndin h\u00e9r n\u00e6st fyrir ofan n\u00e1\u00f0i a\u00f0eins til \u00e1rsins 2014, en h\u00e9r n\u00e6r ferillinn fr\u00e1 2003 til 2020.<\/span><\/p><\/div>\n

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Mynd 5c: Virkni s\u00f3lar s\u00ed\u00f0astli\u00f0in 11.400 \u00e1r, e\u00f0a fr\u00e1 lokum s\u00ed\u00f0ustu \u00cdsaldar<\/strong>.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Beri\u00f0 \u00feessa mynd saman vi\u00f0 Mynd 1a. sem er n\u00e6st efst \u00e1 \u00feessari s\u00ed\u00f0u og s\u00fdnir breytingar \u00e1 hitafari yfir sama t\u00edmabil.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Myndin er fr\u00e1 hinni virtu stofnun Max Planck Institute for Solar System Research<\/a>.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0Greinin er h\u00e9r:\u00a0 \u00a0The Sun is more active now than over the last 8000 years.<\/a>
\u00a0\u00a0<\/span><\/p><\/div>\n

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Mynd 5d: <\/span>S\u00f3lvirknin s\u00ed\u00f0astli\u00f0i\u00f0 \u00e1r\u00fe\u00fasund. <\/span><\/strong>Ferillinn n\u00e6r um \u00fea\u00f0 bil yfir t\u00edmabili\u00f0 900-1950. Var\u00f0andi hitafar m\u00e1 hafa mynd 2d: Hnattr\u00e6nar hitabreytingar s\u00ed\u00f0astli\u00f0in 2000 \u00e1r,\u00a0 <\/em>til hli\u00f0sj\u00f3nar en hafa \u00ed huga a\u00f0 a\u00f0 s\u00e1 ferill n\u00e6r yfir n\u00e6stum tv\u00f6falt lengra t\u00edmabil.<\/span><\/p><\/div>\n

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Breyting \u00ed heildar\u00fatgeislun er a\u00f0eins um 0,1% en breyting \u00ed \u00fatfj\u00f3lubl\u00e1a lj\u00f3sinu yfir 11 \u00e1ra s\u00f3lsveiflu er um t\u00edf\u00f6ld e\u00f0a 1000%. \u00a0\u00a0Jafnvel tv\u00f6falt \u00fea\u00f0 eins og s\u00e9st \u00e1 mynd 5c<\/strong> fr\u00e1 jap\u00f6nsku geimfer\u00f0astofnuninni.<\/p>\n

\"Mynd

Mynd 5e: 20-f\u00f6ld breyting \u00e1 \u00fatfj\u00f3lubl\u00e1rri \u00fatgeislun s\u00f3lar yfir 11 \u00e1ra t\u00edmabil.<\/span><\/p><\/div>\n

S\u00f3lvirknin hefur minnka\u00f0 hratt \u00e1 s\u00ed\u00f0ustu \u00e1rum.\u00a0 Er \u00fea\u00f0 forbo\u00f0i \u00feess a\u00f0 h\u00e1markinu s\u00e9 n\u00e1\u00f0 og hl\u00fdskei\u00f0i\u00f0 a\u00f0 ganga ni\u00f0ur, eins og \u00fea\u00f0 ger\u00f0i fyrir 1000, 2000 og 3000 \u00e1rum eftir nokkurra \u00e1ratuga l\u00f6ng g\u00f3\u00f0\u00e6ri? \u00a0\u00dev\u00ed hafa \u00fdmsir v\u00edsindamenn sp\u00e1\u00f0, en f\u00e1ir hlusta\u00f0. Fari svo, \u00fe\u00e1 mun \u00fea\u00f0 koma \u00ed lj\u00f3s innan \u00e1ratugar.<\/p>\n

\u00a0<\/strong><\/p>\n

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Mynd 5f:\u00a0 Koltv\u00eds\u00fdringur \u00ed andr\u00famsloftinu hefur aukist samfellt \u00e1 undanf\u00f6rnum \u00e1ratugum. Ferillinn er fr\u00e1 www.climate4you.com<\/span>
Superimposed plot of five different global monthly temperature estimates shown individually\u00a0elsewhere<\/a>. As the base period differs for these estimates, they have all been normalised by comparing to the average of their initial 120 months (10 years) from January 1979 to December 198<\/i>8<\/i>.<\/i>\u00a0Click here<\/a>\u00a0to go to the associated comparison of these five temperature records. The heavy black line represents the simple running 37 month (c. 3 year) mean of the average of all temperature estimates (before 1979 only the three surface records). The blue graph shows the amount of atmospheric CO2<\/sub>\u00a0(Mauna Loa station<\/a>, Hawaii, see also\u00a0above<\/a>). The heavy blue line represents the simple running 37 month (c. 3 year) mean of the monthly CO<\/i><\/span>2<\/sub><\/span><\/i>-values.\u00a0<\/i>The scale for atmospheric CO2<\/sub>\u00a0(right) is adjusted to display the CO2<\/sub>-graph roughly parallel to the 1975-2000 temperature increase.\u00a0<\/span>For the first two decades in the 21st<\/sup>\u00a0century a warming of about 0.2\u00b0C per decade is projected for a range of SRES emission scenarios according to the\u00a02007 IPCC Summary for Policymakers<\/a>\u00a0(p.7 and Fig.SPM.5)<\/i>.\u00a0Last month shown: September 2019. Last diagram update: 30 October 2019.<\/span><\/i>.<\/span><\/p><\/div>\n

\u00a0<\/strong><\/p>\n

— — —<\/strong><\/p>\n

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\u00cdsaldir koma og fara….<\/strong><\/p>\n

Kenning Milankovitch \u00e1 kannski ekki heima h\u00e9r, \u00fev\u00ed vi\u00f0 h\u00f6fum veri\u00f0 a\u00f0 sko\u00f0a tilt\u00f6lulega stutt t\u00edmbil. L\u00e1tum \u00fe\u00f3 va\u00f0a…<\/p>\n

Hvernig v\u00e6ri a\u00f0 skyggnast 200.000 \u00e1r aftur \u00ed t\u00edmann, og reyndar 100.000 \u00e1r fram \u00ed t\u00edmann! Hvernig \u00ed \u00f3sk\u00f6punum er \u00fea\u00f0 h\u00e6gt? J\u00fa me\u00f0 \u00fev\u00ed a\u00f0 sko\u00f0a breytingar \u00e1 innbyr\u00f0is afst\u00f6\u00f0u jar\u00f0ar og s\u00f3lar.
\nReyndar var fyrst og fremst \u00e6tlunin a\u00f0 fjalla um ve\u00f0urfar n\u00fat\u00edmans me\u00f0 tilliti til umfj\u00f6llunar um svok\u00f6llu\u00f0 gr\u00f3\u00f0urh\u00fasa\u00e1hrif. \u00dea\u00f0 getur \u00fe\u00f3 veri\u00f0 fr\u00f3\u00f0legt a\u00f0 sko\u00f0a hva\u00f0a hugmyndir menn hafa um ve\u00f0urfar fyrir \u00f3ral\u00f6ngu, og hvernig menn hafa reynt a\u00f0 sk\u00fdra \u00e1st\u00e6\u00f0ur fyrir gr\u00ed\u00f0armiklum sveiflum \u00ed ve\u00f0urfari, sem valdi\u00f0 hafa \u00eds\u00f6ldum og hl\u00fdindaskei\u00f0um \u00e1 v\u00edxl.<\/p>\n

\u00c1ri\u00f0 1941 setti st\u00e6r\u00f0fr\u00e6\u00f0ingurinn Milutin Milankovitch fram kenningu sem sk\u00fdrt getur hvers vegna mikil k\u00f3lnun ver\u00f0ur me\u00f0 tilt\u00f6lulega l\u00f6ngu millibili. Hann reikna\u00f0i \u00fat samanl\u00f6g\u00f0 \u00e1hrif breytinga \u00e1 m\u00f6ndulhalla (obliquity, 41.000 \u00e1ra sveifla), m\u00f6ndulveltu (precession, sbr. skopparakringlu, 19-21,000 \u00e1ra sveifla) og braut jar\u00f0ar umhverfis s\u00f3lu (eccentricity, 100.000 \u00e1ra sveifla).\u00a0 \u00a0 Sj\u00e1 mynd 5e.<\/p>\n

Ni\u00f0ursta\u00f0an s\u00fdnir hven\u00e6r l\u00edkur eru \u00e1 k\u00f6ldum og heitum t\u00edmabilum, og a\u00f0 \u00e1 kuldaskei\u00f0um f\u00e1 sta\u00f0ir \u00e1 60\u00b0N a\u00f0eins sama varma fr\u00e1 s\u00f3linni (insolation) og sta\u00f0ir \u00e1 80\u00b0N f\u00e1 n\u00fa!<\/p>\n

\u00c1hrif m\u00f6ndulveltu og m\u00f6ndulhalla gera \u00fea\u00f0 a\u00f0 verkum, a\u00f0 anna\u00f0 slagi\u00f0 hallar j\u00f6r\u00f0in l\u00edti\u00f0 m\u00f3ti s\u00f3lu a\u00f0 sumri til, og ver\u00f0ur sumarhitinn \u00fev\u00ed l\u00e1gur.<\/p>\n

S\u00ed\u00f0ari ranns\u00f3knir s\u00fdna a\u00f0 fj\u00f6ldi sm\u00e6rri \u00e1hrifa hefur \u00e1hrif \u00e1 heildarmyndina, en kenning Milankovitch er samt sem \u00e1\u00f0ur mj\u00f6g \u00e1hugaver\u00f0 og vel \u00feekkt.<\/p>\n

J\u00e6ja, hven\u00e6r megum vi\u00f0 eiga von \u00e1 n\u00e6stu \u00eds\u00f6ld samkv\u00e6mt \u00feessari kenningu? Sko\u00f0a\u00f0u vel ne\u00f0sta ferilinn!<\/p>\n

Eins og m\u00f6rgum er kunnugt, \u00fe\u00e1 vir\u00f0ist sem \u00edsaldir hafi skolli\u00f0 \u00e1 me\u00f0 litlum fyrirvara \u00e1 a\u00f0eins nokkrum \u00e1ratugum. Ranns\u00f3knir \u00e1 borkj\u00f6rnum fr\u00e1 Gr\u00e6nlandsj\u00f6kli hafa leitt \u00feetta \u00ed lj\u00f3s. Getur veri\u00f0 a\u00f0 s\u00f3lin hafi komi\u00f0 \u00fear n\u00e6rri og hj\u00e1lpa\u00f0 til vi\u00f0 a\u00f0 setja ferli\u00f0 af sta\u00f0 me\u00f0 langvarandi kuldakasti \u00e1 sama t\u00edma og afsta\u00f0a jar\u00f0ar og s\u00f3lar var \u00f3hagst\u00e6\u00f0 samkv\u00e6mt l\u00edkani Milankovitch? Eins og vi\u00f0 s\u00e1um h\u00e9r \u00e1 undan, \u00fe\u00e1 getur s\u00f3lin veri\u00f0 ansi dynt\u00f3tt!<\/p>\n

Kenning Milankovitch \u00e1 \u00fe\u00f3 ekki vi\u00f0 um breytingar \u00e1 hitafari s\u00ed\u00f0ustu alda og \u00e1ratuga.<\/p>\n

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\"Kenning

Mynd 5g: Kenning Milutin Milankovitch<\/strong> um \u00e1st\u00e6\u00f0ur \u00edsalda er vel \u00feekkt. Me\u00f0 \u00fatreikningum er h\u00e6gt a\u00f0 finna mismunandi hitunar\u00e1hrif s\u00f3lar \u00e1 nor\u00f0urhvel jar\u00f0ar. M\u00f6ndulhalli, m\u00f6ndulvelta og braut jar\u00f0ar breytast me\u00f0 t\u00edmanum.<\/span>
\u00c1 myndinni h\u00e9r til hli\u00f0ar sj\u00e1um vi\u00f0 hvernig \u00feessir \u00fer\u00edr \u00fe\u00e6ttir leggjast saman og mynda samsetta ferilinn sem er ne\u00f0st. T\u00edmaskalinn n\u00e6r 200.000 \u00e1r aftur \u00ed t\u00edmann og 100.000 \u00e1r fram \u00ed t\u00edmann. (L\u00f3\u00f0r\u00e9tti \u00e1sinn er merktur: W\u00f6tt \u00e1 fermetra \u00e1 60\u00b0N)<\/span><\/p><\/div>\n

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\u00a0— — —<\/strong><\/p>\n

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6. \u00c1hrif aukningar CO2<\/sub><\/strong><\/span><\/h2>\n

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Hva\u00f0 merkir \u00fea\u00f0 \u00e1 mannam\u00e1li a\u00f0 styrkur CO2 \u00ed andr\u00famsloftinu s\u00e9 415 ppm, en \u00fea\u00f0 er magn CO2 \u00ed andr\u00famsloftinu \u00ed lok \u00e1rs 2021<\/span>?<\/strong><\/p>\n

Skilur einhver \u00fe\u00e1 st\u00e6r\u00f0? Er \u00fea\u00f0 miki\u00f0 e\u00f0a l\u00edti\u00f0?<\/strong> L\u00edklega gera f\u00e1ir s\u00e9r grein fyrir hva\u00f0 \u00feetta \u00fe\u00fd\u00f0ir \u00e1 mannam\u00e1li. Reynum a\u00f0 \u00fatsk\u00fdra \u00fea\u00f0:<\/p>\n

Vissulega vir\u00f0ist 415 ppm vera st\u00f3r tala, en getur veri\u00f0 a\u00f0 h\u00fan s\u00e9 \u00f6rsm\u00e1?<\/p>\n

415 ppm \u00fe\u00fd\u00f0ir 415 millj\u00f3nustu hlutar en \u00fea\u00f0 er a\u00f0eins 0,0415 %, e\u00f0a \u00fev\u00ed sem n\u00e6st 0,04 %. \u00dea\u00f0 eru heil 10.000 ppm \u00ed 1%.\u00a0 Skammst\u00f6funin ppm stendur fyrir “parts per million”.<\/span><\/p>\n

Me\u00f0 \u00f6\u00f0rum or\u00f0um:\u00a0A\u00f0eins 41 sameind af hverjum 100.000 sameindum andr\u00famloftsins er CO2.<\/strong><\/p>\n

Mi\u00f0a\u00f0 vi\u00f0 n\u00faverandi hra\u00f0a \u00e1 losun manna \u00e1 CO2 tekur \u00fea\u00f0 um \u00ferj\u00fa \u00e1r a\u00f0 b\u00e6ta vi\u00f0 einni sameind af 100.000, \u00feannig a\u00f0 eftir \u00ferj\u00fa \u00e1r ver\u00f0a v\u00e6ntanlega um 42 sameindir af hverjum 100.000 koltv\u00eds\u00fdringur.<\/p>\n

Magn CO2 hefur aukist fr\u00e1 0,0280 % \u00ed 0,0415 % fr\u00e1 \u00fev\u00ed menn f\u00f3ru a\u00f0 brenna kolum og ol\u00edu eftir a\u00f0 i\u00f0nbyltingin h\u00f3fst fyrir um 250 \u00e1rum, en oft er mi\u00f0a\u00f0 vi\u00f0 sm\u00ed\u00f0i fyrstu gufuv\u00e9larinnar um 1770.<\/p>\n

\u00dear sem \u00fea\u00f0 er au\u00f0veldara a\u00f0 segja og skrifa 415 ppm en 0,0415 % er venjan a\u00f0 nota fyrri framsetninguna.<\/p>\n

\u00c1 myndinni h\u00e9r fyrir ne\u00f0an m\u00e1 sj\u00e1 hvernig styrkur CO2 \u00ed andr\u00famsloftinu hefur aukist s\u00ed\u00f0an reglulegar m\u00e6lingar h\u00f3fust.<\/strong> \u00a0Taki\u00f0 eftir a\u00f0 l\u00f3\u00f0r\u00e9tti skalinn byrjar \u00ed 310 ppm, en ekki \u00ed 0 ppm.<\/p>\n

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Mynd 6a. Styrkur CO2 hefur veri\u00f0 m\u00e6ldur \u00e1 Mona Loa fjalli s\u00ed\u00f0an 1958.<\/span><\/p><\/div>\n

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Til gamans er h\u00e9r fyrir ne\u00f0an \u00f6nnur mynd af aukningu CO2 \u00fear sem Y-\u00e1sinn byrjar \u00ed 0 ppm. \u00deessi framsetning er eing\u00f6ngu h\u00f6f\u00f0 h\u00e9r til a\u00f0 minna \u00e1 a\u00f0 \u00e6vinlega er nau\u00f0synlegt\u00a0 a\u00f0 sko\u00f0a vel kv\u00f6r\u00f0un \u00e1sanna, \u00fev\u00ed myndin getur veri\u00f0 villandi ef kvar\u00f0inn \u00e1 \u00feeim er valinn \u00f3heppilega.<\/p>\n

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Mynd 6b. Sama mynd og h\u00e9r a\u00f0 ofan, nema a\u00f0 l\u00f3\u00f0r\u00e9tti \u00e1sinn byrjar \u00ed 0.<\/span><\/p><\/div>\n

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Ef\u00a0tv\u00f6f\u00f6ldun<\/em>\u00a0CO2 veldur 1\u00b0C h\u00e6kkun hvernig m\u00e1 \u00fea\u00f0 vera a\u00f0\u00a0fj\u00f3rf\u00f6ldun<\/em>\u00a0veldur a\u00f0eins 2\u00b0C h\u00e6kkun og\u00a0\u00e1ttf\u00f6ldun<\/em>\u00a03\u00b0C h\u00e6kkun?<\/strong><\/span><\/p>\n

\u00deetta segir IPCC (Nefnd Sameinu\u00f0u \u00fej\u00f3\u00f0anna um loftslagsbreytingar) \u00e1 vefs\u00ed\u00f0u sinni\u00a0h\u00e9r<\/u><\/a>:<\/strong>\u00a0<\/span>Equilibrium GCM 2 x CO2 experiments commonly assume a radiative forcing equivalent to a doubling of CO2 concentration (for example from 300 ppmv to 600 ppmv). In fact the absolute concentrations are not especially important, as the temperature response to increasing CO2 concentration is logarithmic – a doubling from 500 to 1000 ppmv would have approximately the same climatic effect.<\/span><\/span><\/p>\n

\u00c1st\u00e6\u00f0an er s\u00fa a\u00f0 sambandi\u00f0 milli hitafars lofthj\u00fapsins og styrks CO2 er logarithmiskt.<\/strong>\u00a0 \u00c1 myndinni h\u00e9r fyrir ne\u00f0an s\u00e9st \u00feetta greinilega.\u00a0\u00a0Taki\u00f0 eftir a\u00f0 fyrstu 20 ppm af CO2 hafa jafnmikil \u00e1hrif \u00e1 hitastigi\u00f0 og \u00f6ll h\u00e6kkun CO2 fr\u00e1 20 ppm upp \u00ed 300 ppm!<\/em><\/p>\n

\u00dea\u00f0 skiptir ekki m\u00e1li hver h\u00e6kkun hitastigsins fyrir tv\u00f6f\u00f6ldun CO2\u00a0 er. Logaritmiska sambandi\u00f0 gildir alltaf eins og ferlarnir \u00fer\u00edr s\u00fdna. H\u00e6kkunin er alltaf s\u00fa sama fyrir hverja tv\u00f6f\u00f6ldun \u00ed styrk CO2.<\/p>\n

300 ppm -> 600 ppm, h\u00e6kkun um 1\u00b0C\u00a0\u00a0\u00a0\u00a0\u00a0 (Pl\u00fas [e\u00f0a m\u00ednus] \u00e1hrif vegna “feedback” e\u00f0a afturverkunar).
\n600 ppm -> 1200 ppm, h\u00e6kkun um 1\u00b0C\u00a0\u00a0\u00a0 (–“–)
\n1200 ppm -> 2400 ppm, h\u00e6kkun um 1\u00b0C\u00a0 (–“–)<\/p>\n

– – –<\/p>\n

(\u00c1 myndinni h\u00e9r fyrir ne\u00f0an eru \u00fer\u00edr ferlar. Me\u00f0altal h\u00e6kkunar hitastigs vi\u00f0 tv\u00f6f\u00f6ldun CO2 er um 1\u00b0C \u00e1n afturverkunar e\u00f0a “feedbacks”. \u00dea\u00f0 sem er \u00e1hugavert er hve \u00f3l\u00ednulegur ferillinn er og a\u00f0 \u00e1hrifin af h\u00e6kkandi magni CO2 fara hlutfallslega s\u00edminnkandi. Ferlarnir byrja a\u00f0 breikka \u00fear sem magni\u00f0 er or\u00f0i\u00f0 280 ppm (upphaf i\u00f0nbyltingar) og \u00e1 brei\u00f0i hluti ferlanna a\u00f0 s\u00fdna vi\u00f0b\u00f3tarhl\u00fdnun “af mannav\u00f6ldum”, \u00e1n nokkurrar afturverkunar (feedback).\u00a0 \u00cd dag er magni\u00f0 415 ppm, en yr\u00f0i 560 ppm vi\u00f0 tv\u00f6f\u00f6ldun fr\u00e1 upphafi i\u00f0nbyltingar).<\/p>\n

\"\"

Mynd 6c. Mikilv\u00e6gt er a\u00f0 gera s\u00e9r a\u00f0 gera s\u00e9r grein fyrir a\u00f0 \u00e1hrif CO2 \u00e1 hita lofthj\u00fapsins eru logarithmisk. \u00dea\u00f0 \u00fe\u00fd\u00f0ir a\u00f0 hver tv\u00f6f\u00f6ldun styrks veldur s\u00f6mu hl\u00fdnun.<\/span><\/p><\/div>\n

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Hva\u00f0 valda\u00a0<\/strong><\/span>n\u00e1tt\u00faruleg gr\u00f3\u00f0urh\u00fasa\u00e1hrif<\/u> mikilli h\u00e6kkun hitastigs og hve mikil g\u00e6ti h\u00e6kkun hitastigs vegna vi\u00f0b\u00f3tar gr\u00f3\u00f0urh\u00fasa\u00e1hrifum af mannav\u00f6ldum<\/u>\u00a0veri\u00f0?<\/span><\/strong><\/p>\n

Sem betur fer eru\u00a0n\u00e1tt\u00farulegu gr\u00f3\u00f0urh\u00fasa\u00e1hrifin<\/em>\u00a0veruleg, \u00fev\u00ed \u00e1n \u00feeirra v\u00e6ri ekkert l\u00edf \u00e1 j\u00f6r\u00f0inni.\u00a0Hin n\u00e1tt\u00farulegu gr\u00f3\u00f0urh\u00fasa\u00e1hrif n\u00e1 a\u00f0 h\u00e6kka me\u00f0alhita jar\u00f0ar um \u00fev\u00ed sem n\u00e6st 33\u00b0C, e\u00f0a \u00far m\u00ednus 18\u00b0 \u00ed pl\u00fas 15 gr\u00e1\u00f0ur.\u00a0\u00a0<\/strong>\u00dear \u00e1 vatnsgufan e\u00f0a rakinn \u00ed andr\u00famsloftinu l\u00edklega mestan \u00fe\u00e1tt, \u00fev\u00ed vatnsgufan veldur 70-90% gr\u00f3\u00f0urh\u00fasa\u00e1hrifanna.<\/p>\n

\u00dea\u00f0 eru\u00a0vi\u00f0b\u00f3tar gr\u00f3\u00f0urh\u00fasa\u00e1hrifin<\/em><\/strong>\u00a0sem margir hafa \u00e1hyggjur af og stafa af losun manna \u00e1 CO2 og \u00f6\u00f0rum gr\u00f3\u00f0urh\u00fasalofttegundum.\u00a0\u00deessi vi\u00f0b\u00f3ta gr\u00f3\u00f0urh\u00fasa\u00e1hrif hafa hinga\u00f0 til n\u00e1\u00f0 a\u00f0 valda a\u00f0 h\u00e1marki um 1\u00b0C h\u00e6kkun hitastigs, en \u00ed reynd allnokku\u00f0 minni h\u00e6kkun \u00feegar n\u00e1tt\u00farulegar sveiflur hafa veri\u00f0 dregnar fr\u00e1. <\/strong>Gr\u00f3\u00f0urh\u00fasa\u00e1hrif af mannav\u00f6ldum valda \u00fev\u00ed um 1 til 3 % h\u00e6kkun hitastigs umfram \u00fea\u00f0 sem hin n\u00e1tt\u00farulegu gr\u00f3\u00f0urh\u00fasa\u00e1hrif valda, \u00fe.e. 0,5 til 1 gr\u00e1\u00f0a af 33 gr\u00e1\u00f0u h\u00e6kkun n\u00e1tt\u00farulegu gr\u00f3\u00f0urh\u00fasa\u00e1hrifanna.<\/p>\n

\u00c1n hinna g\u00f3\u00f0u gr\u00f3\u00f0urh\u00fasa\u00e1hrifa v\u00e6ri fimbulkuldi \u00e1 j\u00f6r\u00f0inni og l\u00edti\u00f0 l\u00edfsmark.<\/strong><\/p>\n

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\u00a0— — —<\/strong><\/p>\n

 <\/p>\n

Til umhugsunar.\u00a0 \u00a0<\/strong>“Eggi\u00f0 og h\u00e6nan”.<\/strong><\/h3>\n

 <\/p>\n

\"\"

Mynd 6d. Getur veri\u00f0 a\u00f0 breytingar \u00ed lofthita komi \u00e1 undan breytingum \u00ed styrk CO2? Hva\u00f0 s\u00fdnist \u00fe\u00e9r lesandi g\u00f3\u00f0ur?<\/p><\/div>\n

\n
Myndin er fengin a\u00f0 l\u00e1ni \u00far sk\u00fdrslu pr\u00f3fessors Ole Humlum: “State of the Climate 2018”.<\/div>\n<\/div>\n
\n
\n

Myndin s\u00fdnir \u00e1rlegar breytingar<\/em> \u00e1 hitastigi<\/strong> og \u00e1rlegar breytingar<\/em> \u00ed styrk koltv\u00eds\u00fdrings (CO2)<\/strong>. (Ath., breytingar en ekki absolut gildi).<\/p>\n<\/div>\n<\/div>\n

\n
\n

Samkv\u00e6mt myndinni ver\u00f0a breytingar \u00ed styrk CO2 um 12 m\u00e1nu\u00f0um eftir<\/strong> a\u00f0 breytingar ver\u00f0a \u00ed hita. Breytingar \u00e1 styrk CO2 vir\u00f0ast sem sagt elta hitabreytingarnar, en ekki \u00f6fugt.<\/p>\n<\/div>\n<\/div>\n

\n
\n

\u00deetta finnst m\u00e9r umhugsunarvert. Hva\u00f0a sk\u00fdring getur veri\u00f0 \u00e1 \u00feessu?<\/p>\n

Sj\u00e1 greinina:\u00a0 The phase relation between atmospheric carbon dioxide and global temperature<\/strong>
\nhttps:\/\/www.sciencedirect.com\/science\/article\/pii\/S0921818112001658<\/a><\/p>\n<\/div>\n<\/div>\n

\n
(\u00c9g b\u00e6tti inn gulu strikunum \u00e1 myndinni til a\u00f0 \u00fatsk\u00fdra \u00fea\u00f0 sem \u00e9g \u00e1 vi\u00f0).<\/div>\n<\/div>\n

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 <\/p>\n

 <\/p>\n

Hin j\u00e1kv\u00e6\u00f0u \u00e1hrif aukningar CO2 \u00ed andr\u00famsloftinu.<\/strong><\/h3>\n
\n

F\u00e1tt er svo me\u00f0 \u00f6llu illt, a\u00f0 ekki bo\u00f0i nokku\u00f0 gott.<\/p>\n

Koltv\u00eds\u00fdringur er ekki eitra\u00f0ur. Hann er undirsta\u00f0a alls l\u00edfs \u00e1 j\u00f6r\u00f0inni. \u00c1n hans yxi ekki gr\u00e6nn g\u00f3\u00f0ur og matv\u00e6laframlei\u00f0sla v\u00e6ri engin. D\u00fdral\u00edf l\u00edti\u00f0 sem ekkert og v\u00edst er a\u00f0 vi\u00f0 v\u00e6rum ekki h\u00e9r.<\/p>\n

Me\u00f0 hj\u00e1lp s\u00f3lar vinna pl\u00f6nturnar mj\u00f6lvi og sykur \u00far koltv\u00eds\u00fdringnum og losa fr\u00e1 s\u00e9r s\u00farefni. L\u00edfsandi plantanna er koltv\u00eds\u00fdringur, en okkar l\u00edfsandi er s\u00farefni\u00f0. \u00c1n gr\u00e6nu plantanan v\u00e6ri ekkert s\u00farefni og \u00fev\u00ed ekkert d\u00fdral\u00edf.<\/p>\n

Aukning koltv\u00eds\u00fdrings \u00ed andr\u00famsloftinu eykur verulega vaxtarhra\u00f0a gr\u00f3\u00f0urs. \u00dea\u00f0 hefur mj\u00f6g j\u00e1kv\u00e6\u00f0 \u00e1hrif \u00e1 matv\u00e6laframlei\u00f0slu heimsins. Ekki veitir af.<\/p>\n

H\u00e9r \u00e1 landi hefur gr\u00f3\u00f0ri fleygt fram \u00e1 undanf\u00f6rnum \u00e1rum. Sk\u00f3garm\u00f6rk hafa h\u00e6kka\u00f0 og v\u00ed\u00f0a m\u00e1 sj\u00e1 sj\u00e1lfs\u00e1\u00f0 tr\u00e9 vaxa upp \u00fear sem \u00e1\u00f0ur var au\u00f0n. Vi\u00f0 getum \u00feakka\u00f0 \u00fea\u00f0 b\u00e6\u00f0i h\u00e6kku\u00f0um lofthita og auknum styrk koltv\u00eds\u00fdrings.<\/p>\n

\u00cdslenskir gr\u00f3\u00f0urh\u00fasab\u00e6ndur vita a\u00f0 h\u00e6gt er a\u00f0 auka framlei\u00f0sluna verulega me\u00f0 \u00fev\u00ed a\u00f0 losa koltv\u00eds\u00fdring inn \u00ed gr\u00f3\u00f0urh\u00fasin. \u00deess vegana m\u00e1 i\u00f0ulega sj\u00e1 st\u00e1lgeyma e\u00f0a st\u00e6rri tanka me\u00f0 koltv\u00eds\u00fdringi fyrir utan gr\u00f3\u00f0urh\u00fasin eins og \u00e1 mynd 7<\/strong>. Inni \u00ed gr\u00f3\u00f0urh\u00fasunum er styrkur koltv\u00eds\u00fdrings tv\u00f6faldur til fj\u00f3rfaldur \u00feess sem er utan \u00feeirra. \u00cd \u00feessu \u00e1kve\u00f0na gr\u00f3\u00f0urh\u00fasi er hann um 0,09 til 0,1%, e\u00f0a 900 til 1000 ppm. Utan h\u00fassins er styrkurinn 0,04% e\u00f0a 410 ppm.<\/p>\n

\"Mynd

Mynd 6e: Geymir me\u00f0 koltv\u00eds\u00fdringi fyrir utan \u00edslenskt gr\u00f3\u00f0urh\u00fas.<\/span><\/p><\/div>\n

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\"Mynd

Mynd 6f: Tilraunir hafa veri\u00f0 ger\u00f0ar \u00ed \u00fev\u00ed skyni a\u00f0 m\u00e6la vaxtarhra\u00f0a plantna vi\u00f0 mismunsandi styrk koltv\u00eds\u00fdrings. \u00c1 myndinni er veri\u00f0 a\u00f0 gera tilraunir me\u00f0 furu (Eldarica Pine)<\/em>. Lengst til vinstri er styrkurinn s\u00e1 sami og \u00ed andr\u00famsloftinu, e\u00f0a 400 ppm (0,04%). \u00c1 n\u00e6stu mynd hefur 150 ppm veri\u00f0 b\u00e6tt vi\u00f0 \u00feannig a\u00f0 styrkurinn ver\u00f0ur 550 ppm. \u00c1 \u00feri\u00f0ju myndinni er styrkurinn or\u00f0inn 700 ppm og \u00e1 \u00feeirri fj\u00f3r\u00f0u 850 ppm, e\u00f0a meiri en tv\u00f6faldur \u00feess sem er \u00ed andr\u00famsloftinu utandyra. \u00deetta kunna pl\u00f6nturnar svo sannarlega a\u00f0 meta og vaxtarhra\u00f0inn tv\u00f6faldast.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Dr. Sherwood Idso. https:\/\/www.co2science.org\/<\/span><\/p><\/div>\n

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Aukinn styrkur koltv\u00eds\u00fdrings og h\u00e6rri lofthiti hafa gert \u00fea\u00f0 a\u00f0 verkum a\u00f0 gr\u00f3\u00f0ur jar\u00f0ar hefur aukist. H\u00fan er a\u00f0 ver\u00f0a gr\u00e6nni samkv\u00e6mt gervihnattamyndum. Um \u00fea\u00f0 m\u00e1 lesa \u00e1 vefs\u00ed\u00f0u NASA sem nefnist Global Garden Gets Greener<\/a>, en \u00fear er a\u00f0 finna mynd 7c<\/strong>.<\/p>\n

\"Mynd

Mynd 6g: Hin gr\u00e6nkandi j\u00f6r\u00f0 samkv\u00e6mt vefs\u00ed\u00f0u NASA.<\/span><\/p><\/div>\n

Sj\u00e1 einnig grein eftir Dr.\u00a0Patrick J Michaels<\/a> \u00e1 vef Dr. Judith Curry<\/a>: “The most amazing greening on Earth<\/a><\/strong>“.
\n\u00dear eru \u00e1hugaver\u00f0ar myndir.<\/p>\n

H\u00f6fum \u00fea\u00f0 hugfast a\u00f0 koltv\u00eds\u00fdringur, undirsta\u00f0a l\u00edfs \u00e1 j\u00f6r\u00f0inni, er ekki mengun. Magn koltv\u00eds\u00fdrings \u00ed andr\u00famsloftinu m\u00e6list n\u00fa 0,04%. \u00a0 \u00a0Munum einnig a\u00f0 vi\u00f0 erum \u00ed n\u00e1b\u00fdli vi\u00f0 stj\u00f6rnu sem vi\u00f0 k\u00f6llum s\u00f3l. S\u00f3lin veitir okkur birtu og yl\u00a0sem breytist me\u00f0 sveiflum sem n\u00e1 yfir \u00e1ratugi, \u00e1rhundru\u00f0 og \u00e1r\u00fe\u00fasund. Munum eftir sveiflum \u00ed Atlantshafinu og Kyrrahafinu. Munum eftir sveiflum \u00ed \u00fatbrei\u00f0slu haf\u00ediss og breytlegu endurskini. \u00a0 Munum eftir…<\/p>\n

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 <\/p>\n

7. Samantekt<\/strong><\/span><\/h2>\n

\u00cd fyrirs\u00f6gn var spurt: Loftslagsbreytingar af v\u00f6ldum manna e\u00f0a n\u00e1tt\u00faru, e\u00f0a kannski hvort tveggja?\u00a0<\/strong><\/span><\/p>\n

\u00c6tli svari\u00f0 s\u00e9 ekki “hvort tveggja”.<\/span><\/p>\n

\u00c1\u00f0ur<\/a>\u00a0hefur s\u00e1 sem h\u00e9r ritar gert \u00fev\u00ed sk\u00f3na a\u00f0 skiptingin g\u00e6ti hafa veri\u00f0\u00a0veri\u00f0 milli eftirfarinna \u00fe\u00e1tta undanfarna \u00e1ratugi:<\/span><\/p>\n

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    \n
  1. Ytri sveiflur<\/strong> sem v\u00e6ru \u00fe\u00e1 helst breytingar \u00ed s\u00f3linni.<\/span><\/li>\n
  2. Innri sveiflur <\/strong>svo sem breytingar \u00ed hafstraumum og breytingar \u00ed haf\u00eds\/endurskini eins og P\u00e1ll Berg\u00fe\u00f3rsson hefur bent \u00e1.<\/span><\/li>\n
  3. St\u00edgandi sem stafar af s\u00edfelt meiri losun \u00e1 koltv\u00eds\u00fdringi<\/strong>.<\/span><\/li>\n<\/ol>\n

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    \u00deetta er semsagt fl\u00f3ki\u00f0 samspil n\u00e1tt\u00farulegra fyrirb\u00e6ra og \u00e1hrifa losunar manna \u00e1 koltv\u00eds\u00fdringi.<\/strong><\/span><\/p>\n

    Hve miki\u00f0 hver \u00feessara \u00feriggja \u00fe\u00e1tta vegur er \u00f3m\u00f6gulegt a\u00f0 segja.\u00a0 Vi\u00f0 getum \u00feess vegna til einf\u00f6ldunar og br\u00e1\u00f0abirg\u00f0a sagt a\u00f0 hver \u00fe\u00e1ttur valdi svo sem “\u00feri\u00f0jungi”,<\/strong> en au\u00f0vita\u00f0 er \u00fea\u00f0 bara \u00f3r\u00f6kstudd \u00e1giskun \u00fear til vi\u00f0 vitum betur.<\/span>..\u00a0 Hva\u00f0 “\u00feri\u00f0jungur” er n\u00e1kv\u00e6mlega geta menn haft s\u00edna sko\u00f0un \u00e1, m\u00e9r og m\u00ednum a\u00f0 meinalausu.<\/span><\/p>\n

    Sj\u00e1lfur tel \u00e9g a\u00f0 bein og \u00f3bein \u00e1hrif s\u00f3lar s\u00e9u verulega vanmetin, og a\u00f0 \u00fea\u00f0 eigi eftir a\u00f0 koma \u00f3tv\u00edr\u00e6tt \u00ed lj\u00f3s. N\u00e1tt\u00faran mun hafa s\u00ed\u00f0asta or\u00f0i\u00f0 :-).<\/span><\/p>\n

    Vi\u00f0 sj\u00e1um greinilega \u00e1 hitaferlinum fr\u00e1 Bresku Ve\u00f0urstofunni (mynd 3a<\/strong>) a\u00f0 Litlu \u00cds\u00f6ldinni l\u00fdkur ekki fyrr en um 1920, \u00fe\u00e1 ver\u00f0ur mj\u00f6g hr\u00f6\u00f0 hl\u00fdnun fram a\u00f0 1945, s\u00ed\u00f0an kyrrsta\u00f0a til um 1975 er hitinn fer a\u00f0 r\u00edsa hratt til \u00e1rsins 2000, og a\u00f0 lokum meira og minna kyrrsta\u00f0a til dagsins \u00ed dag.<\/p>\n

    Eftirtektarvert er a\u00f0 \u00e1 t\u00edmabilinu 1920 til 1945 er \u00e1l\u00edka hr\u00f6\u00f0 og \u00e1l\u00edka mikil h\u00e6kkun \u00e1 hitastigi og \u00e1 t\u00edmabilinu 1975 til 2000. Hvort tveggja 25 \u00e1ra t\u00edmabil. \u00dea\u00f0 er umhugsunarvert a\u00f0 losun manna \u00e1 koltv\u00eds\u00fdringi var tilt\u00f6lulega l\u00edtil fyrr en eftir mi\u00f0ja s\u00ed\u00f0ustu \u00f6ld er losunin f\u00f3r hratt vaxandi. \u00dea\u00f0 fl\u00e6kir au\u00f0vita\u00f0 m\u00e1li\u00f0 d\u00e1l\u00edti\u00f0.\u00a0 Var \u00fea\u00f0 kannski n\u00e1tt\u00faran sem var a\u00f0 verki \u00e1 fyrra t\u00edmabilinu og mannf\u00f3lki\u00f0 \u00e1 hinu s\u00ed\u00f0ara?\u00a0 E\u00f0a \u00e1 n\u00e1tt\u00faran einhvern \u00fe\u00e1 \u00ed hitabreytingunum yfir allt t\u00edmabili\u00f0? \u00dea\u00f0 hefur h\u00fan alltaf gert.<\/p>\n

    Vi\u00f0 t\u00f6kum eftir \u00fev\u00ed a\u00f0 me\u00f0alhitinn yfir allt t\u00edmabili\u00f0 er nokkurn vegin s\u00e1 sami og m\u00e6ldist \u00ed kyrrst\u00f6\u00f0unni 1945-1975. V\u00e6ri ekki e\u00f0lilegra a\u00f0 mi\u00f0a h\u00e6kkun lofthitans vi\u00f0 \u00fea\u00f0 t\u00edmabil frekar en Litlu \u00cds\u00f6ldina eins og gert er?\u00a0 \u00de\u00e1 v\u00e6ri h\u00e6kkunin sem vi\u00f0 v\u00e6rum me\u00f0 \u00e1hyggjur af um 0,5 gr\u00e1\u00f0ur \u00ed sta\u00f0 1 gr\u00e1\u00f0u.<\/p>\n

    \u00deri\u00f0jungur af 0,5 gr\u00e1\u00f0um er t\u00e6plega 0,2 gr\u00e1\u00f0ur, (0,17\u00b0). Ekki er \u00fea\u00f0 n\u00fa miki\u00f0. Getur veri\u00f0 a\u00f0 \u00e1hrif koltv\u00eds\u00fdrings hafi ekki veri\u00f0 meiri?\u00a0 \u00a0Hummm…\u00a0 \u00a0 Ekki skal neitt fullyrt \u00ed \u00fessum m\u00e1lum. (N\u00fa er ma\u00f0ur kominn \u00e1 h\u00e1lan \u00eds \ud83d\ude42 )<\/span><\/p>\n

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     <\/p>\n

    \n

    8. Vi\u00f0auki<\/strong><\/span><\/h2>\n

    H\u00e9r eru nokkur vi\u00f0t\u00f6l vi\u00f0 e\u00f0a greinar eftir \u00feekkta \u00edslenska ve\u00f0urfr\u00e6\u00f0inga. \u00dea\u00f0 ver\u00f0ur a\u00f0 hafa \u00fea\u00f0 \u00ed huga a\u00f0 sko\u00f0un g\u00f3\u00f0ra v\u00edsindamanna breytist eftir \u00fev\u00ed sem \u00feeir hafa meiri g\u00f6gn. \u00dea\u00f0 getur \u00fev\u00ed vel veri\u00f0 a\u00f0 eftirfarandi s\u00e9 ekki n\u00e1kv\u00e6mlega \u00e1lit \u00feeirra \u00ed dag.<\/h2>\n

    Hverju sv\u00f6ru\u00f0u \u00feessir fr\u00e6\u00f0imenn \u00de\u00f3r Jakobsson<\/strong> og Trausti J\u00f3nsson<\/strong> \u00ed Vi\u00f0skiptabla\u00f0inu 13. desember 2006?<\/p>\n

    \u00deessir v\u00edsindamenn eru me\u00f0al \u00feeirra reyndustu \u00e1 svi\u00f0i ve\u00f0ur- og loftslagsfr\u00e6\u00f0a h\u00e9r \u00e1 landi.<\/p>\n

    \"\"<\/p>\n

     <\/p>\n

     <\/p>\n

    \n

    Vi\u00f0tal vi\u00f0 P\u00e1l Berg\u00fe\u00f3rsson<\/strong> og Trausta J\u00f3nsson<\/strong> \u00ed B\u00e6ndabla\u00f0inu\u00a0 6. febr\u00faar 2014:<\/p>\n

    Greinina m\u00e1 s\u00e6kja sem pdf \u00ed fullri upplausn me\u00f0 \u00fev\u00ed a\u00f0 smella h\u00e9r<\/strong><\/a>.<\/p>\n

    \"\"<\/p>\n

    \n

    Stutt grein eftir \u00de\u00f3r Jakobsson<\/strong> \u00ed DV 21. j\u00fan\u00ed 2000:
    \n\"\"—<\/p>\n

    Vi\u00f0tal vi\u00f0 P\u00e1l Berg\u00fe\u00f3rsson \u00ed Fr\u00e9ttabla\u00f0inu 1. mars 2013:<\/p>\n

    \"\"

    Vi\u00f0tal vi\u00f0 P\u00e1l Berg\u00fe\u00f3rsson \u00ed Fr\u00e9ttabla\u00f0inu 1. mars 2013<\/p><\/div>\n

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     <\/p>\n

    Magn\u00fas J\u00f3nsson fyrrverandi ve\u00f0urstofustj\u00f3ri: Ranns\u00f3knir \u00ed herkv\u00ed hagsmuna?<\/a><\/p><\/blockquote>\n

Sv\u00e6\u00f0in sem merkt eru me\u00f0 gr\u00e6nu eru s\u00e9rlega \u00e1hugaver\u00f0.\u00a0 Lengst til h\u00e6gri eru hl\u00fdindin sem glatt hafa okkur undanfarna \u00e1ratugi og kallast Modern Warm Period<\/strong>. Fyrir um 1000 \u00e1rum var anna\u00f0 hl\u00fdskei\u00f0 sem st\u00f3\u00f0 nokkra \u00e1ratugi og kallast Medieval Warm Period<\/strong>. \u00de\u00e1 var jafnvel enn hl\u00fdrra en \u00ed dag. A\u00f0 minnsta kosti \u00e1l\u00edka hl\u00fdtt.\u00a0 Fyrir 2000 \u00e1rum, me\u00f0an \u00e1 Roman Warm Period <\/strong>st\u00f3\u00f0, var svo enn hl\u00fdrra og mun hl\u00fdrra var fyrir r\u00famum 3000 \u00e1rum \u00e1 t\u00edmabili sem kalla\u00f0 er Minoan<\/a> Warm Period<\/strong>.\u00a0 Hva\u00f0 veldur \u00feessum \u00e1ratugal\u00f6ngu hl\u00fdskei\u00f0um sem hafa komi\u00f0 reglulega me\u00f0 um 1000 \u00e1ra millibili? Vi\u00f0 getum skyggnst lengra aftur \u00ed t\u00edma og sj\u00e1um a\u00f0 fyrir 7000 og 8000 \u00e1rum var lang hl\u00fdjast fr\u00e1 \u00fev\u00ed er \u00eds\u00f6ld lauk. Holocene Climate Optimum<\/strong> kallast s\u00e1 t\u00edmi.<\/p>\n