{"id":2763,"date":"2019-09-27T02:00:15","date_gmt":"2019-09-27T02:00:15","guid":{"rendered":"https:\/\/himinn.fjarver.is\/mengunsjavar\/?p=2763"},"modified":"2021-03-14T16:21:49","modified_gmt":"2021-03-14T16:21:49","slug":"9-2-titill","status":"publish","type":"post","link":"https:\/\/himinnoghaf.is\/mengunsjavar\/index.php\/2019\/09\/27\/9-2-titill\/","title":{"rendered":"9.2 Loftslagsbreytingar \u00e1 nor\u00f0ursl\u00f3\u00f0um"},"content":{"rendered":"

Losun gr\u00f3\u00f0urh\u00fasalofttegunda af mannav\u00f6ldum \u2013 s\u00e9rstaklega vegna brennslu jar\u00f0eldsneytis \u2013 hefur aukist miki\u00f0 \u00e1 s\u00ed\u00f0ustu \u00e1rum og \u00e1ratugum. Aflei\u00f0ing \u00feessarar losunar er aukinn styrkur kold\u00edox\u00ed\u00f0s og annarra gr\u00f3\u00f0urh\u00fasalofttegunda \u00ed andr\u00famsloftinu, sem aftur veldur s\u00farnun sj\u00e1var og loftslagsbreytingum s.s. hnattr\u00e6nni hl\u00fdnun, h\u00e6kkun sj\u00e1varbor\u00f0s og fj\u00f6lgun \u00f6fgaatbur\u00f0a \u00e1 bor\u00f0 vi\u00f0 hitabylgjur, aftaka\u00farkomu o.fl. (\u00cdtarlega er fjalla\u00f0 um loftslagsbreytingar og s\u00farnun sj\u00e1var \u00ed kafla 3<\/a>). Hl\u00fdnun \u00e1 nor\u00f0ursl\u00f3\u00f0um hefur veri\u00f0 hra\u00f0ari en annars sta\u00f0ar \u00ed heiminum og sama gildir um s\u00farnun sj\u00e1var.<\/p>\n

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Mynd 9.2. Vinstra megin \u00e1 efri hluta myndarinnar m\u00e1 sj\u00e1 me\u00f0alhita \u00e1 nor\u00f0urhveli jar\u00f0ar. Nor\u00f0ursl\u00f3\u00f0ir eru kaldasta sv\u00e6\u00f0i nor\u00f0urhvels. H\u00e6gra megin \u00e1 efri hluta myndarinnar m\u00e1 sj\u00e1 fr\u00e1vik fr\u00e1 me\u00f0alhita \u00e1ri\u00f0 2016 bori\u00f0 saman vi\u00f0 me\u00f0alhita \u00e1ranna 1980-1989. Eins og \u00fear s\u00e9st er hl\u00fdnunin mest \u00e1 nor\u00f0ursl\u00f3\u00f0um. Ne\u00f0ri hluti myndarinnar s\u00fdnir fr\u00e1vik fr\u00e1 me\u00f0alhita \u00e1ranna 1850-1900 annars vegar \u00e1 heimsv\u00edsu og hins vegar \u00e1 nor\u00f0ursl\u00f3\u00f0um. Sj\u00e1 m\u00e1 a\u00f0 \u00e1 s\u00ed\u00f0ustu \u00e1rum hefur hl\u00fdnunin veri\u00f0 mun meiri \u00e1 nor\u00f0ursl\u00f3\u00f0um en \u00e1 heimsv\u00edsu.<\/p><\/div>\n

\u00c1hrif hl\u00fdnunar \u00e1 ve\u00f0urfar, l\u00edfr\u00edki og umhverfi nor\u00f0ursl\u00f3\u00f0a eru veruleg. Haf\u00edsinn hefur minnka\u00f0 hratt (sj\u00e1 mynd 9.3 og myndband 3.5 \u00ed kafla 3.5<\/a>) og hitastig hefur \u00e1 k\u00f6flum veri\u00f0 \u00f3venju h\u00e1tt \u2013 jafnvel 20\u00b0C h\u00e6rra en e\u00f0lilegt myndi teljast. \u00deessar breytingar \u00f3gna l\u00edfr\u00edki sv\u00e6\u00f0isins og hafa \u00e1hrif \u00e1 b\u00fasetuskilyr\u00f0i frumbyggja. Margar frumbyggjabygg\u00f0ir eiga n\u00fa \u00feegar undir h\u00f6gg a\u00f0 s\u00e6kja \u00ed f\u00e9lags- og efnahagslegu tilliti. \u00c1 s\u00ed\u00f0ustu \u00e1rum hafa gr\u00f3\u00f0ureldar einnig geisa\u00f0 \u00e1 sv\u00e6\u00f0inu.<\/p>\n

Sem fyrr segir hefur hl\u00fdnun \u00e1 nor\u00f0ursl\u00f3\u00f0um valdi\u00f0 br\u00e1\u00f0nun haf\u00edss. \u00cds endurkastar s\u00f3largeislum, en \u00feegar \u00edsinn br\u00e1\u00f0nar blasir vi\u00f0 d\u00f6kkur haffl\u00f6turinn sem gleypir \u00ed sig meira af geislun s\u00f3larinnar, sem aftur veldur meiri hl\u00fdnun. \u00deetta er d\u00e6mi um svokalla\u00f0a magnandi sv\u00f6run, sem er megin\u00e1st\u00e6\u00f0a aukinnar hl\u00fdnunar \u00e1 nor\u00f0ursl\u00f3\u00f0um. Br\u00e1\u00f0nun s\u00edfrerans \u00e1 sv\u00e6\u00f0inu veldur einnig magnandi sv\u00f6run. S\u00edfreri er kolefnisr\u00edkur frosinn jar\u00f0vegur sem \u00feekur um 24% af landsv\u00e6\u00f0i nor\u00f0urhvels og n\u00e6r m.a. yfir st\u00f3r sv\u00e6\u00f0i \u00ed Alaska, Kanada, S\u00edber\u00edu og \u00e1 Gr\u00e6nlandi. \u00deegar s\u00edfrerinn \u00fei\u00f0nar losnar kolefni, sem hefur veri\u00f0 bundi\u00f0 \u00ed \u00feessum frosna jar\u00f0vegi, \u00fat \u00ed andr\u00famslofti\u00f0 b\u00e6\u00f0i sem metan og kold\u00edox\u00ed\u00f0. Auk \u00feess a\u00f0 valda auknum gr\u00f3\u00f0urh\u00fasa\u00e1hrifum og \u00fear me\u00f0 auknum loftslagsbreytingum veldur br\u00e1\u00f0nun s\u00edfrerans \u00fdmsum vandam\u00e1lum fyrir \u00edb\u00faa sv\u00e6\u00f0isins \u00fear sem jar\u00f0vegurinn ver\u00f0ur \u00f3st\u00f6\u00f0ugur og mannvirki \u00e1 sv\u00e6\u00f0inu geta or\u00f0i\u00f0 fyrir tj\u00f3ni. Byggingar og umfer\u00f0armannvirki geta t.d. sigi\u00f0 og skekkst. Ummerki um magnandi sv\u00f6run \u00e1 sv\u00e6\u00f0inu eru n\u00fa \u00feegar s\u00fdnileg og me\u00f0 \u00e1framhaldandi hl\u00fdnun geta \u00feau or\u00f0i\u00f0 enn meira \u00e1berandi og n\u00e1\u00f0 langt \u00fat fyrir sv\u00e6\u00f0i\u00f0.<\/p>\n

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Mynd 9.3. Vinstra megin m\u00e1 sj\u00e1 l\u00e1gmarks\u00fatbrei\u00f0slu haf\u00edssins \u00e1 nor\u00f0urskautinu \u00e1ri\u00f0 2019 samanbori\u00f0 vi\u00f0 me\u00f0altal l\u00e1gmarksins \u00e1 t\u00edmabilinu 1981-2010 (rau\u00f0a l\u00ednan). H\u00e6gra megin m\u00e1 sj\u00e1 \u00feverskur\u00f0 af jar\u00f0vegi sem inniheldur \u00e1r\u00fe\u00fasunda gamlan s\u00edfrera \u00ed Alaska en \u00ed honum er g\u00edfurlegt magn kolefnis bundi\u00f0.<\/p><\/div>\n

Breytingarnar \u00e1 nor\u00f0ursl\u00f3\u00f0um vegna loftslagsbreytinga eru margv\u00edslegar. Me\u00f0 br\u00e1\u00f0nun \u00edss ver\u00f0a t.a.m. breytingar \u00e1 l\u00edfsskilyr\u00f0um \u00fe\u00f6runga sem vaxa \u00e1 yfirbor\u00f0i \u00edss (l\u00edka ne\u00f0ansj\u00e1var) og mynda grunn f\u00e6\u00f0uke\u00f0junnar. \u00d3vissa r\u00edkir um \u00e1hrif \u00feessara breytinga \u00e1 l\u00edfr\u00edki nor\u00f0ursl\u00f3\u00f0a. \u00de\u00e1 hefur br\u00e1\u00f0nun \u00edssins einnig mikil \u00e1hrif \u00e1 afkomu d\u00fdra s.s. \u00edsbjarna og n\u00e1hvala. Vei\u00f0ar \u00e1 n\u00e1hv\u00f6lum hafa \u00ed gegnum t\u00ed\u00f0ina gegnt mikilv\u00e6gu hlutverki \u00ed f\u00e6\u00f0u\u00f6flun frumbyggja, \u00fear sem \u00feeir hafa m.a. fengi\u00f0 C-v\u00edtam\u00edn \u00far h\u00fa\u00f0 og spiki hvalsins. N\u00e1hvalir halda sig innan um haf\u00eds og leynast \u00feannig fyrir h\u00e1hyrningum \u2013 n\u00e1tt\u00farulegum \u00f3vinum n\u00e1hvala. Minnkandi haf\u00eds g\u00e6ti \u00fev\u00ed leitt til f\u00e6kkunar n\u00e1hvala. Br\u00e1\u00f0nun \u00edss hefur \u00e1hrif \u00e1 farlei\u00f0ir d\u00fdra og vei\u00f0imanna. Lei\u00f0ir sem \u00e1\u00f0ur voru f\u00e6rar \u00e1 \u00eds eru or\u00f0nar \u00f3f\u00e6rar e\u00f0a illa f\u00e6rar.<\/p>\n

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Mynd 9.4. Leysingavatn ofan \u00e1 \u00eds vi\u00f0 nor\u00f0vesturhluta Gr\u00e6nlands \u00ed j\u00fan\u00ed 2019. Hef\u00f0bundnar farlei\u00f0ir vei\u00f0imanna ver\u00f0a torfarnari me\u00f0 aukinni br\u00e1\u00f0nun \u00edssins.<\/p><\/div>\n

Fylgst er me\u00f0 l\u00edffr\u00e6\u00f0ilegri fj\u00f6lbreytni \u00e1 nor\u00f0urskautinu me\u00f0 v\u00f6ktunar\u00e1\u00e6tlun CBMP<\/span> (Circumpolar Biodiversity Monitoring Program), \u00fear sem nor\u00f0urskautssv\u00e6\u00f0inu er skipt upp \u00ed 8 v\u00f6ktunarsv\u00e6\u00f0i. \u00deessi v\u00f6ktun n\u00e6gir ekki til a\u00f0 l\u00fdsa \u00e1standi og \u00fer\u00f3un \u00fdmissa \u00fe\u00e1tta \u00ed l\u00edfr\u00edkinu me\u00f0 fulln\u00e6gjandi h\u00e6tti en gefur \u00fe\u00f3 mikilv\u00e6gar v\u00edsbendingar:<\/p>\n