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Rashin sanyi

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Rashin sanyi
Rashin sanyi da ake gani a kan yanayin zafi na duniya na NASA na 2015, sannan shekarar da ta fi zafi a cikin jerin zafin jiki na NASA - launuka suna nuna yanayin zafin jiki (NASA / NOAA; 20 Janairu 2016). [1]

Ruwan sanyi a Arewacin Atlantic (wanda ake kira rami na dumama na Arewacin Atlantic [2]) yanayin zafi ne mai sanyi na ruwan teku, wanda ke shafar Atlantic Meridional Overturning Circulation (AMOC) wanda yake wani ɓangare na zagayawar thermohaline, mai yiwuwa yana da alaƙa da narkewar duniya da aka haifar da narke kankara na Greenland.[3]

Bincike

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A shekara ta 2005, masu bincike na Burtaniya sun lura cewa kwararar kogin Gulf Stream ta arewa ta ragu da kusan kashi 30% tun shekara ta 1957. Ba zato ba tsammani, masana kimiyya a Woods Hole suna auna sabuntawa na Arewacin Atlantic yayin da Duniya ta zama mai dumi. Binciken da suka yi ya nuna cewa hazo yana ƙaruwa a cikin manyan latitudes na arewa, kuma kankara yana narkewa a sakamakon haka. Ta hanyar ambaliyar teku ta arewa tare da ruwa mai laushi mai yawa, dumamar duniya na iya, a ka'idar, karkatar da ruwan Gulf Stream wanda yawanci ke gudana zuwa arewa, ya wuce tsibirin Burtaniya da Norway, kuma ya sa su zagaya zuwa ga ma'auni. Idan wannan ya faru, yanayin Turai zai yi tasiri sosai.[4][5]

Don Chambers daga Kwalejin Kimiyya ta Marine ta USF ta ambata, "Babban tasirin jinkirin AMOC ana sa ran ya zama sanyi da lokacin rani a kusa da Arewacin Atlantic, da karuwar yanki a matakin teku a bakin tekun Arewacin Amurka. " [6] James Hansen da Makiko Sato sun bayyana, "Rashin jinkirin AMCO wanda ke haifar da sanyaya ~ 1 ° C kuma watakila yana shafar tsarin yanayi ya bambanta da rufewar yankin AMOC wanda ke sanyaya Arewacin Atlantic digiri da yawa; tasirin teku zai kasance a kan guguwa da yawa na ƙarshe".[7]

Dalilin da ya sa

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AMOC yana motsawa ta hanyar zafin teku da bambancin salinity. Babban hanyar da za ta iya haifar da yanayin zafin jiki na teku mai sanyi ya dogara ne akan gaskiyar cewa ruwan sha yana rage gishiri na ruwan teku, kuma ruwan da ya fi sanyi ba zai iya nutsewa ba saboda ba su da yawa fiye da ruwan gishiri a ƙarƙashin su. Karin ruwan sha da aka lura mai yiwuwa ya samo asali ne daga narkewar kankara ta Greenland.

Bincike

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AMOC-Index tun daga 900 AZ tare da raguwa tun daga ~1850; Rahmstorf et al. (2015) [8]

Masana kimiyya na yanayi Michael Mann na Jihar Penn da Stefan Rahmstorf daga Cibiyar Nazarin Tasirin Yanayi ta Potsdam sun ba da shawarar cewa yanayin sanyi da aka lura a cikin shekaru na rikodin zafin jiki alama ce cewa zafin Kudancin Tekun Atlantika (AMOC) na iya raunanawa. Sun buga binciken da suka yi, kuma sun kammala cewa yaduwar AMOC ta nuna raguwa ta musamman a cikin karni na ƙarshe, kuma cewa narkewar Greenland mai yiwuwa ne mai ba da gudummawa.[8] Tom Delworth na NOAA ya ba da shawarar cewa bambancin yanayi, wanda ya haɗa da hanyoyi daban-daban, a nan wato Arewacin Atlantic Oscillation da Atlantic Multidecadal Oscillation ta hanyar yanayin zafi na teku suma abu ne. Wani binciken da Jon Robson et al. daga Jami'ar Reading suka yi a shekarar 2014 sun kammala game da anomaly, "...samar da cewa babban canji a cikin AMOC yana tasowa yanzu. " Wani binciken da Didier Swingedouw ya yi ya kammala cewa jinkirin AMOC a cikin 1970s na iya kasancewa ba a taɓa gani ba a cikin karni na ƙarshe. [9][10]

Wani binciken da aka buga a cikin 2016, ta masu bincike daga Jami'ar Kudancin Florida, Kanada da Netherlands, sun yi amfani da bayanan tauraron dan adam na GRACE don kimanta ruwan sha daga Greenland. Sun kammala cewa ruwan sha yana hanzarta, kuma zai iya haifar da rushewar AMOC a nan gaba, wanda zai shafi Turai da Arewacin Amurka.[11]

Wani binciken da aka buga a cikin 2016, ya sami ƙarin shaidar tasiri mai yawa daga hauhawar matakin teku ga Gabashin Gabashin Amurka. Binciken ya tabbatar da binciken da aka yi a baya wanda ya gano yankin a matsayin wuri mai zafi don tasowa na teku, tare da yiwuwar karkatar da sau 3-4 fiye da matsakaicin matakin teku na duniya. Masu bincike sun danganta yiwuwar karuwa ga tsarin yaduwar teku da ake kira samar da ruwa mai zurfi, wanda aka rage saboda jinkirin AMOC, wanda ke haifar da ƙarin aljihun ruwa mai dumi a ƙasa. Bugu da ƙari, binciken ya lura: "Sakamako namu ya nuna cewa ƙimar fitar da carbon mafi girma tana ba da gudummawa ga karuwar [Hawan matakin teku] a wannan yankin idan aka kwatanta da matsakaicin duniya".

Tun daga shekara ta 2004 shirin RAPID yana sa ido kan yaduwar teku.

Manazarta

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  1. ↑ Brown, Dwayne; Cabbage, Michael; McCarthy, Leslie; Norton, Karen (20 January 2016). "NASA, NOAA Analyses Reveal Record-Shattering Global Warm Temperatures in 2015". NASA. Retrieved 21 January 2016.
  2. ↑ "North Atlantic warming hole impacts jet stream". ScienceDaily (in Turanci). Retrieved 2019-04-24.
  3. ↑ "If you doubt that the AMOC has weakened, read this". RealClimate (in Turanci). 28 May 2018. Retrieved 2019-04-24.
  4. ↑ Bryden, H.L.; H.R. Longworth; S.A. Cunningham (2005). "Slowing of the Atlantic meridional overturning circulation at 25° N". Nature. 438 (7068): 655–657. Bibcode:2005Natur.438..655B. doi:10.1038/nature04385. PMID 16319889. S2CID 4429828.
  5. ↑ Curry, R.; Mauritzen, C. (2005). "Dilution of the northern North Atlantic in recent decades". Science. 308 (5729): 1772–1774. doi:10.1126/science.1109477. PMID 15961666. S2CID 36017668.
  6. ↑ "Melting Greenland ice sheet may affect global ocean circulation, future climate". Phys.org. 2016.
  7. ↑ James Hansen; Makiko Sato (2015). "Predictions Implicit in "Ice Melt" Paper and Global Implications".
  8. ↑ 8.0 8.1 Stefan Rahmstorf; Jason E. Box; Georg Feulner; Michael E. Mann; Alexander Robinson; Scott Rutherford; Erik J. Schaffernicht (2015). "Exceptional twentieth-century slowdown in Atlantic Ocean overturning circulation" (PDF). Nature Climate Change. 5 (5): 475–480. Bibcode:2015NatCC...5..475R. doi:10.1038/nclimate2554. Cite error: Invalid <ref> tag; name "rahmstorf2015" defined multiple times with different content
  9. ↑ Jon Robson; Dan Hodson; Ed Hawkins; Rowan Sutton (2014). "Atlantic overturning in decline?" (PDF). Nature Geoscience. 7 (1): 2–3. Bibcode:2014NatGe...7....2R. doi:10.1038/ngeo2050. S2CID 29399465.
  10. ↑ Didier Swingedouw (2015). "Oceanography: Fresh news from the Atlantic". Nature Climate Change. 5 (5): 411–412. Bibcode:2015NatCC...5..411S. doi:10.1038/nclimate2626.
  11. ↑ "Melting Greenland ice sheet may affect global ocean circulation, future climate". Phys.org. 2016.
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