{"id":524,"date":"2015-08-24T16:45:06","date_gmt":"2015-08-24T16:45:06","guid":{"rendered":"http:\/\/192.168.1.70\/wordpress\/?p=524"},"modified":"2019-12-12T11:45:10","modified_gmt":"2019-12-12T11:45:10","slug":"hin-agnarsmaa-03-breyting-i-medalhita-jardar","status":"publish","type":"post","link":"http:\/\/www.agust.net\/wordpress\/2015\/08\/24\/hin-agnarsmaa-03-breyting-i-medalhita-jardar\/","title":{"rendered":"A\u00f0eins 0,3% breyting \u00ed me\u00f0alhita jar\u00f0ar fr\u00e1 \u00fev\u00ed fyrir i\u00f0nbyltingu…"},"content":{"rendered":"
\"L\u00f3\u00f0r\u00e9tti

L\u00f3\u00f0r\u00e9tti \u00e1sinn \u00e1 l\u00eduritinu er \u00feaninn gr\u00ed\u00f0arlega miki\u00f0 \u00fat. Um \u00fea\u00f0 bil einn mill\u00edmetri \u00e1 hitam\u00e6linum er st\u00e6kka\u00f0ur n\u00e6stum 100 falt \u00ed 100 mm e\u00f0a 10 cm.<\/p><\/div>\n

 <\/p>\n

S\u00ed\u00f0astli\u00f0in 150 \u00e1r, e\u00f0a fr\u00e1 um 1860 hefur me\u00f0alhiti jar\u00f0ar h\u00e6kka\u00f0 um \u00fev\u00ed sem n\u00e6st 0,8\u00b0C. Einhverjir vilja kannski mi\u00f0a vi\u00f0 skammvinna kulda- e\u00f0a hitatoppa og f\u00e1 \u00fe\u00e1 \u00fat breytingu sem nemur 1,0\u00b0C, en \u00fe\u00e1 er n\u00fa n\u00e1nast veri\u00f0 a\u00f0 teygja lopann. Hva\u00f0 sem \u00fev\u00ed l\u00ed\u00f0ur, \u00fe\u00e1 er veri\u00f0 a\u00f0 mi\u00f0a vi\u00f0 h\u00e6kkun fr\u00e1 s\u00ed\u00f0ustu \u00e1ratugum Litlu \u00edsaldarinnar svok\u00f6llu\u00f0u.<\/p>\n

Me\u00f0alhiti jar\u00f0ar er um 15\u00b0C. \u00a0 \u00c1 myndinni<\/a> h\u00e9r a\u00f0 ofan er reyndar s\u00fdnt fr\u00e1vik<\/em> fr\u00e1 \u00feessum me\u00f0alhita. \u00a0 \u00deess vegna er l\u00f3\u00f0r\u00e9tti \u00e1sinn kvar\u00f0a\u00f0ur fr\u00e1 -0,4\u00b0 upp \u00ed +0,6\u00b0C. L\u00f3\u00f0r\u00e9tti \u00e1sinn n\u00e6r yfir a\u00f0eins\u00a0<\/span>1 gr\u00e1\u00f0u, \u00fe.e. sama og bili\u00f0 milli tveggja strika \u00e1 bleika m\u00e6linum h\u00e9r fyrir ne\u00f0an. \u00a0 \u00deetta er gr\u00ed\u00f0arleg st\u00e6kkun, ef til vill \u00a0um 100-f\u00f6ld!<\/span><\/p>\n

\u00deessi mikla \u00fat\u00feensla \u00e1 l\u00f3\u00f0r\u00e9tta skalanum gerir \u00fea\u00f0 a\u00f0 verkum a\u00f0 almennt \u00e1ttar f\u00f3lk sig ekki \u00e1 hver hitabreytingin er \u00ed raun.<\/p>\n

\u00c1 bleika m\u00e6linum (reyndar hv\u00edtur m\u00e6lir \u00e1 bleikum vegg) \u00a0m\u00e1 sj\u00e1 me\u00f0alhita lofthj\u00fapsins vi\u00f0 yfirbor\u00f0 \u00a0fl\u00f6kta milli \u00e1ranna\u00a01860 og 2010. \u00dear sj\u00e1um vi\u00f0 betur hva\u00f0 \u00feetta er \u00ed raun l\u00edtil breyting.<\/span> H\u00fan er svo l\u00edtil a\u00f0 vi\u00f0 yr\u00f0um hennar ekki v\u00f6r \u00ed daglegu amstri. \u00c1 venjulegum degi er algengt a\u00f0 lofthitinn breytist 10 sinnum meira, og yfir \u00e1ri\u00f0 miklu miklu meira. \u00deetta er minna en munur \u00e1 hita \u00ed herbergjum heima hj\u00e1 okkur.<\/p>\n

Lofthitinn breytist um t\u00e6plega 1,0\u00b0C vi\u00f0 100 metra breytingu \u00e1 h\u00e6\u00f0. N\u00e1nar tilteki\u00f0 um 0,65\u00b0C. Hann breytist um 0,1\u00b0C vi\u00f0 15 metra h\u00e6\u00f0arbreytingu en 0,1\u00b0C er sama og h\u00e6\u00f0in \u00e1 hverjum litlum ferningi myndinni h\u00e9r a\u00f0 ofan. Vi\u00f0 getum jafnvel minnst \u00e1 a\u00f0 stundum er veri\u00f0 a\u00f0 metast um hva\u00f0 hafi veri\u00f0 hl\u00fdjasta \u00e1ri\u00f0 fr\u00e1 upphafi m\u00e6linga, m\u00e6lt yfir alla jar\u00f0arkringluna. Metast \u00fe\u00e1 stundum v\u00edsindamenn jafnvel\u00a0 um mun sem a\u00f0eins nemur 0,02\u00b0C…\u00a0 \u00c1 myndinni kemur fram a\u00f0 \u00e1 fyrstu tugum \u00feessara m\u00e6linga var m\u00e6li\u00f3vissan +\/-0,2\u00b0C, en \u00e1 s\u00ed\u00f0utu \u00e1rum +\/-0,1\u00b0C.<\/p>\n

Samt eru menn a\u00f0 metast og jafnvel r\u00edfast h\u00e1st\u00f6fum um breytingar sem eru \u00fea\u00f0 litlar a\u00f0 \u00fe\u00e6r eru ekki t\u00f6lfr\u00e6\u00f0ilega markt\u00e6kar.\u00a0 \u00a0Sj\u00e1 t.d. h\u00e9r<\/a>.<\/p>\n

\"Hitam\u00e6lir

Hitam\u00e6lir 1860-2010<\/p><\/div>\n

Vi\u00f0 vitum a\u00f0 \u00fea\u00f0 var \u00e1m\u00f3ta hl\u00fdtt og \u00ed dag fyrir 1000 \u00e1rum, allnokku\u00f0 hl\u00fdrra fyrir 2000 \u00e1rum og t\u00f6luvert hl\u00fdrra \u00a0fyrir um 3000 \u00e1rum. Samt erum vi\u00f0 a\u00f0 hr\u00e6\u00f0ast\u00a0hl\u00fdindin sem vi\u00f0 nj\u00f3tum \u00ed dag og \u00a0\u00e1saka okkur um a\u00f0 hafa valdi\u00f0 \u00feeim. Reyndar er \u00feessum hl\u00fdindum a\u00f0eins misskipt. H\u00e9r \u00e1 landi h\u00f6fum vi\u00f0 veri\u00f0 l\u00e1ns\u00f6m og noti\u00f0 meiri hl\u00fdnunar en 0,8\u00b0, en \u00fea\u00f0 er \u00f6nnur saga.<\/p>\n

Ma\u00f0ur hl\u00fdtur samt a\u00f0 d\u00e1st a\u00f0 \u00fev\u00ed hve st\u00f6\u00f0ugur lofthiti jar\u00f0ar er.<\/span>
\n \u00cd v\u00edsindum er vaninn a\u00f0 m\u00e6la hitann \u00ed Kelvin gr\u00e1\u00f0um, en \u00fear byrjar skalinn vi\u00f0 alkul. S\u00f3lin hitar j\u00f6r\u00f0ina okkar fr\u00e1 alkuli \u00ed l\u00edfv\u00e6nlegan hita, e\u00f0a fr\u00e1 -273\u00b0C \u00a0 \u00ed \u00a0 +15\u00b0C a\u00f0 jafna\u00f0i.<\/span>
\n \u00dea\u00f0 er jafngilt hitun fr\u00e1 \u00a00 K \u00a0 til \u00a0 288 K.<\/span><\/p>\n

\u00c1 Kelvin skalanum er me\u00f0alhitinn 288K (um 15\u00b0C). Hitabreytingin g\u00e6ti \u00fev\u00ed veri\u00f0 fr\u00e1 288,0K \u00a0 \u00ed \u00a0 288,8K. \u00deetta er ekki nema um 0,3% breyting sem ver\u00f0ur a\u00f0 teljast l\u00edti\u00f0. \u00a0 \u00a0Merkilega l\u00edti\u00f0.<\/span><\/p>\n

Einhver kann a\u00f0 malda \u00ed m\u00f3inn og segja h\u00e6kkunina vera mun meiri, e\u00f0a fr\u00e1 15,0\u00b0C \u00a0 \u00ed \u00a0 15,8\u00b0C sem er vi\u00f0 fyrstu s\u00fdn um 5% h\u00e6kkun. \u00dea\u00f0 er \u00fe\u00f3 markleysa a\u00f0 mi\u00f0a vi\u00f0 Celc\u00edus gr\u00e1\u00f0ur. Vi\u00f0 g\u00e6tum alveg eins mi\u00f0a\u00f0 vi\u00f0 Farenheit og sagt h\u00e6kkunina vera fr\u00e1 59,0\u00b0F \u00a0 \u00ed \u00a0 60,5\u00b0F og fengi\u00f0 \u00fat 2,5% h\u00e6kkun. \u00a0Nei, r\u00e9tta a\u00f0fer\u00f0in er a\u00f0 mi\u00f0a vi\u00f0 Kelvin gr\u00e1\u00f0ur og \u00fe\u00e1 f\u00e6st 0,3% h\u00e6kkun \u00e1 s\u00ed\u00f0astli\u00f0num 150 \u00e1rum.<\/p>\n

 <\/p>\n

\u00c1l\u00edka hl\u00fdtt var fyrir 1000 \u00e1rum og \u00ed dag. \u00a0Bl\u00e1i ferillinn n\u00e6r til \u00e1rsins 1854, en hefur veri\u00f0 framlengdur lauslega til dagsins \u00ed dag me\u00f0 rau\u00f0um lit. Ferillinn er samkv\u00e6mt m\u00e6lingum \u00ed borholu \u00e1 Gr\u00e6nlandsj\u00f6kli. Sj\u00e1 \u00a0 www.climate4you.com<\/span><\/a><\/span> , \u00a0kafla\u00a0“Global Temperature”. \u00a0\u00deetta er sem sagt \u00e1 Gr\u00e6nlandi en ekki \u00a0me\u00f0alhiti jar\u00f0ar, en gefur samt v\u00e6ntanlega \u00ed st\u00f3rum dr\u00e1ttum hugmynd um \u00fer\u00f3unina. N\u00e1nar h\u00e9r<\/a> um hl\u00fdindin fyrir 1000 \u00e1rum.<\/p>\n

Hafi veri\u00f0 \u00e1m\u00f3ta hl\u00fdtt og \u00ed dag \u00feegar \u00cdsland bygg\u00f0ist (Medieval Warm Period) var \u00fe\u00f3 enn hl\u00fdrra fyrir um 2000 \u00e1rum (Roman Warm Period) og mun hl\u00fdrra fyrir r\u00famum 3000 \u00e1rum (Minoan Warm Period). \u00a0Hvers vegna?<\/p>\n

 <\/p>\n

\"Mynd

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. \u00a0Taki\u00f0 eftir<\/strong> a\u00f0 l\u00f3\u00f0r\u00e9tti skalinn vinstra meginn s\u00fdnir lofthitann \u00e1 Gr\u00e6nlandsj\u00f6kli, en l\u00f3\u00f0r\u00e9tti skalinn h\u00e6gra megin s\u00fdnir nokkurn vegin \u00e1\u00e6tla\u00f0 fr\u00e1vik fr\u00e1 me\u00f0alhita jar\u00f0ar, en s\u00fa breyting er h\u00e9r \u00e1\u00e6tlu\u00f0 um helmingi minni en hitabreytingin \u00e1 j\u00f6klinum.<\/em><\/p><\/div>\n

 <\/p>\n

 <\/p>\n

Hitabreytingin \u00e1 undanf\u00f6rnum \u00e1rum er \u00ed raun merkilega l\u00edtil og s\u00e9st varla s\u00e9 mi\u00f0a\u00f0 vi\u00f0 Kelvin hitaskalann \ud83d\ude42 :<\/p>\n

\"S\u00e9

S\u00e9 teikna\u00f0ur hitaferill sem s\u00fdnir hl\u00fdnun jar\u00f0ar fr\u00e1 alkuli \u00ed Kelv\u00edn-gr\u00e1\u00f0um, \u00fe\u00e1 s\u00e9st ekki nein breyting. Svo l\u00edtil er h\u00fan.<\/p><\/div>\n

 <\/p>\n

Til umhugsunar:<\/span><\/strong><\/p>\n

Loftslagskerfin samanstanda af \u00f3lgukenndu (turbulent) hafinu sem er \u00ed snertingu vi\u00f0 \u00f3lgukenndan lofthj\u00fapinn. \u00deessi kerfi eru \u00e1 reikistj\u00f6rnu sem sn\u00fdst \u00ed s\u00edfellu og er b\u00f6\u00f0u\u00f0 \u00ed s\u00f3larlj\u00f3si sem sk\u00edn \u00f3jafnt \u00e1 yfirbor\u00f0 jar\u00f0ar, mest n\u00e6rri mi\u00f0baug en minnst n\u00e6ri p\u00f3lunum. Vetur og sumur skiptast \u00e1. S\u00edfelldur flutningur \u00e1 varma og raka \u00e1 s\u00e9r sta\u00f0 milli \u00feessara s\u00edkviku ka\u00f3t\u00edsku kerfa.<\/span><\/p>\n

\u00cd hafinu eru straumar og sveiflur sem n\u00e1 yfir t\u00edmabil sem m\u00e6last fr\u00e1 d\u00f6gum til \u00e1r\u00fe\u00fasunda. Hafi\u00f0 hefur \u00e1hrif \u00e1 lofthj\u00fapinn og \u00f6fugt. Yfirbor\u00f0 jar\u00f0ar er mj\u00f6g \u00f3reglulegt og m\u00f3tar \u00fea\u00f0 vindakerfin. Rakinn \u00ed lofthj\u00fapnum hefur gr\u00ed\u00f0arlega mikil \u00e1hrif og er a\u00f0al \u00e1hrifavaldurinn s\u00e9 liti\u00f0 til hl\u00fdnunar af v\u00f6ldum svokalla\u00f0ra gr\u00f3\u00f0urh\u00fasa\u00e1hrifa. Jafnvel inngeislun s\u00f3lar er sveiflukennd.<\/span><\/p>\n

Stundum eru leggjast \u00e1hrif \u00feessara tilviljunarkenndu kerfa saman, heildar\u00e1hrif \u00feeirra geta or\u00f0i\u00f0 tilt\u00f6lulega mikil um t\u00edma, en \u00e1 \u00f6\u00f0rum t\u00edmum vinna \u00feau \u00e1 m\u00f3ti hverju \u00f6\u00f0ru og ver\u00f0a \u00fe\u00e1 \u00e1hrifin l\u00edtil.<\/span><\/p>\n

\u00deetta ka\u00f3t\u00edska kerfi \u00e1 yfirbor\u00f0i jar\u00f0ar gerir \u00fea\u00f0 a\u00f0 verkum a\u00f0 hitafari\u00f0 getur or\u00f0i\u00f0 \u00f3lgukennt, \u00e1n \u00feess a\u00f0 ytra \u00e1reiti svo sem breytileg s\u00f3lgeislun e\u00f0a breytilegur styrkur koltv\u00eds\u00fdrings \u00feurfi a\u00f0 koma til. \u00deessar ka\u00f3t\u00edsku, s\u00edkviku og \u00f3lgukenndu sveiflur geta ef til vill \u00fatsk\u00fdrt hitasveiflur sem or\u00f0i\u00f0 hafa \u00e1 undanf\u00f6rnum \u00e1r\u00fe\u00fasundum fr\u00e1 \u00feeim t\u00edma sem k\u00f6llum yfirleitt \u00eds\u00f6ld og sj\u00e1st \u00e1 myndinni h\u00e9r a\u00f0 ofan.<\/span><\/p>\n

 <\/p>\n

 <\/p>\n

Spurning:\u00a0 Var loftslagi\u00f0 fyrir 150 \u00e1rum, \u00fe.e. \u00e1\u00f0ur en \u00fea\u00f0 byrja\u00f0i a\u00f0 hl\u00fdna, betra og “r\u00e9ttara” en \u00ed dag? Vill f\u00f3lk almennt hverfa aftur til Litlu \u00edsaldarinar?
\nSj\u00e1 til d\u00e6mis: Hva\u00f0 er e\u00f0lilegt ve\u00f0urfar…?<\/a><\/strong><\/p>\n

 <\/p>\n

 <\/p>\n

“Svo gengur \u00fea\u00f0 til \u00ed heiminum a\u00f0 sumir hj\u00e1lpa erroribus \u00e1 gang
\nog a\u00f0rir leitast vi\u00f0 a\u00f0 \u00fatry\u00f0ja aftur \u00feeim hinum s\u00f6mu erroribus.
\nHafa svo hvorir tveggju nokku\u00f0 a\u00f0 i\u00f0ja.”<\/span><\/em><\/h3>\n

 <\/p>\n

\u00a0\u00c1rni Magn\u00fasson handritasafnari.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

  S\u00ed\u00f0astli\u00f0in 150 \u00e1r, e\u00f0a fr\u00e1 um 1860 hefur me\u00f0alhiti jar\u00f0ar h\u00e6kka\u00f0 um \u00fev\u00ed sem n\u00e6st 0,8\u00b0C. Einhverjir vilja kannski mi\u00f0a vi\u00f0 skammvinna kulda- e\u00f0a hitatoppa og f\u00e1 \u00fe\u00e1 \u00fat breytingu sem nemur 1,0\u00b0C, en \u00fe\u00e1 er n\u00fa n\u00e1nast veri\u00f0 a\u00f0 teygja lopann. Hva\u00f0 sem \u00fev\u00ed l\u00ed\u00f0ur, \u00fe\u00e1 er veri\u00f0 a\u00f0 mi\u00f0a vi\u00f0 h\u00e6kkun fr\u00e1…<\/p>\n","protected":false},"author":2,"featured_media":1258,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[8],"tags":[],"_links":{"self":[{"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/posts\/524"}],"collection":[{"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/comments?post=524"}],"version-history":[{"count":65,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/posts\/524\/revisions"}],"predecessor-version":[{"id":2486,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/posts\/524\/revisions\/2486"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/media\/1258"}],"wp:attachment":[{"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/media?parent=524"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/categories?post=524"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.agust.net\/wordpress\/wp-json\/wp\/v2\/tags?post=524"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}