{"id":648,"date":"2015-11-16T22:40:09","date_gmt":"2015-11-16T22:40:09","guid":{"rendered":"http:\/\/192.168.1.70\/wordpress\/?p=648"},"modified":"2023-01-19T13:54:41","modified_gmt":"2023-01-19T13:54:41","slug":"hvad-er-edlilegt-vedurfar","status":"publish","type":"post","link":"http:\/\/www.agust.net\/wordpress\/2015\/11\/16\/hvad-er-edlilegt-vedurfar\/","title":{"rendered":"Hva\u00f0 er e\u00f0lilegt ve\u00f0urfar…?"},"content":{"rendered":"

Er loftslag e\u00f0lilegt og \u00e6skilegt\u00a0 eins og \u00fea\u00f0 var fyrir 100 til 150 \u00e1rum?<\/strong><\/p>\n

\"A<\/a>

A Christmas Carol eftir Charles Dickens kom \u00fat um mi\u00f0ja 19. \u00f6ld, en \u00fe\u00e1 var um 1 gr\u00e1\u00f0u kaldara en \u00ed dag. Enn \u00e1ttu eftir a\u00f0 l\u00ed\u00f0a nokkrir \u00e1ratugir af Litlu \u00eds\u00f6ldinni, en vi\u00f0 mi\u00f0um samt h\u00e6kkun hita fr\u00e1 \u00feessum kalda t\u00edma.\u00a0 Hvers vegna?<\/span><\/p><\/div>\n

(Upphaflega \u00e1 Moggabloggi \u00e1ri\u00f0 2015).<\/span><\/p>\n

Spurt er: Hva\u00f0 er e\u00f0lilegt ve\u00f0urfar? Er loftslag e\u00f0lilegt og \u00e6skilegt\u00a0 eins og \u00fea\u00f0 var fyrir 100 til 150 \u00e1rum?<\/strong> \u00a0\u00dea\u00f0 felst \u00ed kenningunni um ska\u00f0legar loftslagsbreytingar, \u00fe.e. hl\u00fdnun fr\u00e1 \u00feessu t\u00edmabili. \u00a0\u00a0J\u00f6r\u00f0in hefur hl\u00fdna\u00f0 um \u00fev\u00ed sem n\u00e6st 1 gr\u00e1\u00f0u\u00a0 s\u00ed\u00f0astli\u00f0in 100 \u00e1r e\u00f0a jafnvel s\u00ed\u00f0astli\u00f0in 150<\/em> \u00e1r\u00a0 segja og skrifa v\u00edsinda- og leikmenn.<\/p>\n

\u00cd \u00feessum or\u00f0um v\u00edsinda- og leikmanna felst einnig a\u00f0 loftslag hafi veri\u00f0 e\u00f0lilegt \u00e1 \u00feeim t\u00edma me\u00f0an\u00a0 losun manna \u00e1 koltv\u00eds\u00fdringi var enn \u00f3veruleg. A\u00f0 loftslag hafi veri\u00f0 \u00e6skilegra \u00e1 s\u00ed\u00f0ustu \u00e1ratugum litlu \u00edsaldar en \u00fea\u00f0 er \u00ed dag vilja margir meina. \u00d6ll hl\u00fdnun hafi veri\u00f0 \u00f3\u00e6skileg og jafnvel sl\u00e6m.<\/span><\/p>\n

\"Breska<\/a>

Breska ve\u00f0urstofan Met Office: Hnattr\u00e6nar breytingar \u00e1 hita fr\u00e1 1850 til 2013. S\u00ed\u00f0ustu \u00e1ratugir 19. aldar tilheyra Litlu \u00eds\u00f6ldinni svok\u00f6llu\u00f0u.<\/span>
Taki\u00f0 eftir gr\u00f6nnu strikunum sem ganga upp og ni\u00f0ur \u00far hverjum m\u00e6lipunkti. \u00deau t\u00e1kna \u00f3vissubil (skekkjufr\u00e1vik) \u00feess punkts. Lengst til h\u00e6gri er \u00f3vissubili\u00f0 +\/-0,1, en lengst til vinstri +\/-0,2<\/span>.\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Mj\u00f6g mikilv\u00e6gt er a\u00f0 \u00e1 svona myndum s\u00e9 m\u00e6li\u00f3vissan s\u00fdnd. \u00dev\u00ed mi\u00f0ur er \u00fea\u00f0 sjaldnast raunin.<\/p><\/div>\n

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Samkv\u00e6mt m\u00e6lingum er tali\u00f0 a\u00f0 hitastig jar\u00f0ar hafi h\u00e6kka\u00f0 um \u00fev\u00ed sem n\u00e6st 1,0\u00b0C s\u00ed\u00f0an um 1850. Kannski er \u00fea\u00f0 0,8\u00b0\u00a0 \u00fev\u00ed \u00f3vissum\u00f6rkin eru samkv\u00e6mt ferlinum +\/- 0,2\u00b0.\u00a0 \u00a0 \u00a0Hvers 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.<\/span> Skekkir \u00fea\u00f0 ekki a\u00f0eins myndina?<\/p>\n

Dr. J\u00f8rgen Peder Steffensen<\/a> jar\u00f0e\u00f0lisfr\u00e6\u00f0ingur og pr\u00f3fessor hj\u00e1 hinni virtu stofnun\u00a0 Niels Bohr Institutet<\/a>, K\u00f8benhavns Universitet, segir a\u00f0 hitam\u00e6lingar hafi hafist \u00e1 kaldasta t\u00edmabili s\u00ed\u00f0ustu 10.000 \u00e1ra, og a\u00f0 vi\u00f0 mi\u00f0um hl\u00fdnun undafarinna \u00e1ratuga vi\u00f0 \u00fea\u00f0<\/em>.\u00a0 \u00a0Mj\u00f6g erfitt s\u00e9 \u00feess vegna a\u00f0 s\u00fdna fram \u00e1 hvort n\u00faverandi hl\u00fdindi stafi af mannav\u00f6ldum e\u00f0a eigi s\u00e9r n\u00e1tt\u00farulegar orsakir. Sj\u00e1 h\u00e9r<\/a>.<\/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 til 1900, \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.<\/em><\/span><\/p>\n

(A\u00f0eins er \u00e1 reiki vi\u00f0 hva\u00f0a t\u00edma hitah\u00e6kkunin er mi\u00f0u\u00f0. Stundum 1860, stundum 1880 og stundum 1910. Jafnvel er mi\u00f0a\u00f0 vi\u00f0<\/span> “ve\u00f0urfari\u00f0 fyrir i\u00f0nbyltingu<\/a>“, en i\u00f0nbyltingin er almennt talin hafa hafist \u00e1 18. \u00f6ld, og stundum mi\u00f0a<\/span> sagnfr\u00e6\u00f0ingar<\/a> vi\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 eins og greinilegt er ef myndin er sko\u00f0u\u00f0. \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<\/span> h\u00e9r<\/a>. Sumir mi\u00f0a vi\u00f0 1850, en<\/span> a\u00f0rir ekki fyrr en 1920<\/a>).<\/span><\/p>\n

Vi\u00f0 sj\u00e1um greinilega \u00e1 hitaferlinum fr\u00e1 Bresku Ve\u00f0urstofunni\u00a0a\u00f0 Litlu \u00cds\u00f6ldinni l\u00fdkur ekki fyrr en um 1920.<\/a>\u00a0 Var Litla \u00eds\u00f6ldin e\u00f0lilegt \u00e1stand, og er hl\u00fdnunin undanfarna \u00f6ld \u00f3e\u00f0lilegt \u00e1stand?\u00a0 \u00a0Var hl\u00fdskei\u00f0i\u00f0 sem landn\u00e1msmennirnir nutu fyrir um \u00e1r\u00fe\u00fasundi (Medieval Climate Optimum) einnig \u00f3e\u00f0lilegt og \u00f3\u00e6skilegt?<\/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.<\/strong> 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. Sj\u00e1 l\u00ednuriti\u00f0 me\u00f0 CO2 h\u00e9r fyrir ne\u00f0an. \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\u00e1tt \u00ed hitabreytingunum yfir allt t\u00edmabili\u00f0? \u00a0.<\/p>\n

Vi\u00f0 t\u00f6kum eftir \u00fev\u00ed \u00e1 myndinni fr\u00e1 Bresku ve\u00f0urstofunni (Met Office) h\u00e9r fyrir ofan a\u00f0 me\u00f0alhitinn yfir allt t\u00edmabili\u00f0 er nokkurn vegin s\u00e1 sami og m\u00e6ldist \u00ed kyrrst\u00f6\u00f0unni 1945-1975. Reyndar er l\u00e1r\u00e9tta l\u00ednan vi\u00f0 0,0\u00b0C \u00f6rl\u00edti\u00f0 ofar. \u00a0V\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 \u00fea\u00f0 bil 0,5\u00b0 \u00ed sta\u00f0\u00a0 1\u00b0. \u00dea\u00f0 munar um minna.\u00a0<\/span><\/p>\n

\u00dea\u00f0 m\u00e1 einnig skj\u00f3ta \u00fev\u00ed a\u00f0, a\u00f0 ef fundin er h\u00e6kkun hitastigs fr\u00e1 segjum 1860 til 2010 me\u00f0 \u00fev\u00ed a\u00f0 reikna mismuninn, \u00fe\u00e1 ver\u00f0ur a\u00f0 taka tillit til \u00feess hver skekkjum\u00f6rk eru og reikna heildarskekjum\u00f6rk. Sj\u00e1 textann undir myndinni fr\u00e1 Bresku ve\u00f0urstofunni h\u00e9r a\u00f0 ofan. Vi\u00f0 getum anna\u00f0 hvort lagt skekkjum\u00f6rkin (skekkjufr\u00e1vikin) beint saman, e\u00f0a reikna\u00f0 kva\u00f0ratr\u00f3tina af summu skekkjumarkanna \u00ed \u00f6\u00f0ru veldi (r\u00e9ttara). Heildarskekkjum\u00f6rkin ver\u00f0a \u00fe\u00e1 +\/-0,3\u00b0 e\u00f0a +\/-0,2\u00b0. \u00deetta \u00fe\u00fd\u00f0ir a\u00f0 vi\u00f0 getum\u00a0 skrifa\u00f0 a\u00f0 h\u00e6kkunin s\u00e9 1\u00b0 +\/-0,2 e\u00f0a \u00e1 bilinu 0,8 til 1,2 gr\u00e1\u00f0a.\u00a0<\/em><\/span><\/p>\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 “fyrir i\u00f0nbyltingu”<\/span><\/p><\/div>\n

https:\/\/www.metoffice.gov.uk\/research\/news\/2018\/global-surface-temperatures-in-2017<\/a><\/p>\n

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\u00cd fyrirs\u00f6gn \u00feessa pistils stendur: Hva\u00f0 er e\u00f0lilegt ve\u00f0urfar?<\/em> \u00a0Er \u00fea\u00f0 eins og \u00fea\u00f0 er \u00ed dag, eins og um mi\u00f0ja s\u00ed\u00f0ustu \u00f6ld, e\u00f0a \u00e1 Litlu is\u00f6ldinni eins og \u00e1 t\u00edmum Charles Dickens?<\/strong><\/span><\/p>\n

Svo vir\u00f0ist sem margir (flestir?) vilji a\u00f0 hnattr\u00e6nt loftslag ver\u00f0i aftur eins og \u00fea\u00f0 var \u00e1 s\u00ed\u00f0ustu \u00e1ratugum Litlu \u00edsaldar, \u00fe.e. \u00e1 \u00feeim \u00e1rum sem fj\u00f6ldi \u00cdslendinga h\u00e9lt til vesturheims \u00ed leit a\u00f0 betra l\u00edfi…\u00a0 \u00a0\u00a0<\/span><\/strong><\/p>\n

\"Styrkur<\/a>

Styrkur koltv\u00eds\u00fdrings (CO2) \u00ed andr\u00famsloftinu fr\u00e1 \u00e1rinu 1750 til 2010.<\/span><\/p><\/div>\n

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A\u00f0 lokum er h\u00e9r hitaferill s\u00ed\u00f0ustu 2000 \u00e1ra, \u00fe.e. fr\u00e1 \u00e1rinu 0 (e\u00f0a fr\u00e1 \u00e1rinu 1 ef menn kj\u00f3sa \u00fea\u00f0 heldur):<\/p>\n

\"\"

Hitafar jar\u00f0ar s\u00ed\u00f0astli\u00f0in 2000 \u00e1r.<\/span><\/p><\/div>\n

<\/h2>\n

— — —<\/h2>\n

Hvort er n\u00fa betra, kuldi e\u00f0a hiti?<\/h2>\n

Hi\u00f0 virta l\u00e6knisfr\u00e6\u00f0i-v\u00edsindarit\u00a0<\/span>The Lancet<\/span><\/em>: <\/span>Cold weather kills 20 times as many people as hot weather<\/a><\/p>\n

“Cold weather kills 20 times as many people as hot weather, according to an international study analyzing over 74 million deaths in 384 locations across 13 countries. The findings, published in\u00a0The Lancet, also reveal that deaths due to moderately hot or cold weather substantially exceed those resulting from extreme heat waves or cold spells…”.<\/p>\n

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Kr\u00e6kjur:<\/p>\n

Um haf\u00eds fyrir Su\u00f0urlandi\u00a0– \u00a0fr\u00e1 landn\u00e1mi til \u00feessa dags<\/strong>
\n\u00de\u00f3r Jakobsson<\/span>\u00a09.5.2006
\nhttp:\/\/www.vedur.is\/hafis\/frodleikur\/nr\/326<\/a><\/span><\/h3>\n

\u00dear m\u00e1 t.d. lesa um \u00e1ri\u00f0 1881, sem er \u00e1 \u00fev\u00ed t\u00edmabili sem h\u00e6kkun lofthita er mi\u00f0u\u00f0 vi\u00f0:<\/p>\n

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