A duniyar tamu akwai manyan kankara wadanda suka mamaye sandunan arewa da kudu. Wannan kankara ba kawai a cikin teku take ba amma ana samunta a tsaunukan tsaunuka. Wadannan sanannun kankara an san su da glaciers. Lokacin da waɗannan glaciers suka kai girman girma wanda yawanci suna rufe duka kuma yankuna masu faɗi, ana kiran su iyakokin kankara na pola.
A cikin wannan labarin zamu gaya muku duk halaye, mahimmancin su, kuzarin ƙarfin waɗannan iyakokin iyakacin duniya da abin da zai faru idan duk waɗannan tarin kankara sun ƙare.
Samuwar kankara
Don samar da hanya ga iyakokin pola, ya zama dole a fara sanin yadda ake yin kankara don su iya yaɗuwa ta yadda da ƙarshe suke gina murfin polar. Duk ɗaukar kankara wanda ya bazu yayin ƙarshe glaciation ko shekarun kankara gyara kankara. Waɗannan ƙanƙan kankara suna da mahimmancin gaske azaman wakilai masu lalacewa da magina sauƙi, ƙasa da wuri mai faɗi.
Wani dalilin da yasa suke da mahimmanci shine saboda sune babbar hanyar samun ruwa mai kyau a doron kasa. Akwai rayayyun halittu da yawa da ke amfani da ruwan narkewar lokacin ƙanƙarar don wanzuwa, sake haifuwa ko sanya shi mazauninsu na asali.
Wadannan kankara ana yin su ne ta hanyar taruwa, shekara zuwa shekara, dusar kankara da take sauka a kasa da gangaren kwari. Suna cikin manyan tsaunuka. Kaurin zai iya kaiwa wani babban rabo idan dusar da ta ɓace saboda narkewar lokacin rani bai kai wanda yake taruwa a lokacin dusar ƙanƙara ba.
Producedananan nauyin wannan dusar ƙanƙan an samar da shi saboda kowane dusar ƙanƙara ana matse shi a kan wanda aka ajiye a baya. Idan zafin narkarwar ya yi nasarar narke kankirin, zai sa shi yin kauri ya fara matsawa zuwa kasan kwarin.
Yawan dusar ƙanƙara yawanci yakan haɓaka tare da zurfin saboda akwai adadin dusar ƙanƙara mai yawa a kowane yanki, kasancewar ya zama ƙarami. Wannan ƙamshin da suke da shi shine tushen glacier kuma yana gudana kamar dai ruwa ne. A cikin gilashin yana motsawa da sauri fiye da yankuna na gefe, saboda haka galibi akwai karyewa, damuwa da kuma miƙawa wanda ke haifar da manyan fasa.
Laarfafawar launin fata
Kankara yana motsawa kuma yana tumɓuke duwatsun da suke tsinkaye waɗanda suke kan hanyarsa. Gutsuttsin dutsen da ya samo asali daga wannan motsi na kankara an san su da moraines. Yankin da ke ƙarshen glacier shine inda ake yin narkewa. Anan, zaku iya ganin samuwar wasu ƙananan tsaunuka waɗanda ake kira terminal moraine.
Matukar dai kankara ke kiyaye yankin tara abubuwa a cikin saman dusar kankara daga hazo, tokawar kankarar zai kasance da rai. Aƙarshe, a cikin ƙananan yankin, ƙanƙararwar ta narke, ta samar da ƙananan rafuka na ruwa mai tsafta.
Akwai wasu kankara wadanda suke ratsa kwaruruka a gindin wani tsauni. Lokacin da suka haɗu tare don samar da babban kankara an san shi da piedmont.
Iyakoki mara iyaka da kankara
Da zarar mun fahimci abin da ke kankara, yadda yake yake da kuma yadda tasirinsa yake, sai mu ci gaba da bayanin kankara ta kankara. Idan kankara da muka ambata ɗazu ya mamaye filaye da tsibirai masu tsayi da ƙanana, an san shi da murfin polar. Waɗannan iyakokin iyakacin duniya galibi ana haifuwarsu ne a cikin kankara mai tsayi kuma suna gangara kwari. A ƙarshe, sukan isa tekun a wasu lokuta.
Idan kankara tana da fadi sosai har ta kai ta ko'ina nahiya, ana kiranta takardar kankara ta nahiyar. Wannan yana faruwa ne tare da iyakokin kankara na Arctic da Antarctica. Wannan babban kankarar yana gudana daga waje har sai ya isa tekun kuma anan ne yake rabewa zuwa girma daban-daban yana samarda dusar kankara.
Ana amfani da kalmar iyakoki don bayyana bambancin kankara da aka samo a Antarctica da Greenland. Saboda haka, Duk lokacin da muke magana game da batun ɗumamar yanayi ko canjin yanayi muna magana ne game da narkewar kankararriyar kankara. Waɗannan iyakokin iyakokin an kafa su ne a cikin zamanin kankara na Pleistocene, a lokacin Quaternary kuma ya zo ya mamaye yawancin emasashen Arewacin duniya.
An san hular zinare a matsayin mayafin glacial kuma galibi suna da tsawo na Fiye da murabba'in kilomita miliyan 1,8. Dangane da kauri, suna kan iyakar mita 2.700. Waɗannan iyakokin iyakokin suna rufe mafi yawan yankin Greenland. Ginin gado yana fitowa ne kawai a kusa da bakin teku inda ƙanƙarar ke da ƙarfi sosai kuma gutsuttukan da ke yin harsunan kankara. Lokacin da harsuna suka isa tekun, sai su kara ballewa zuwa kankara a lokacin narkewa, suna yin kankara.
Icebergs suna da tasirin kansu kuma suna ɓacewa tsawon shekaru. Hannun sandar wannan tasirin ya lullube Antarctica, kawai wannan glacier tana da fadin kasa kilomita murabba'i miliyan 13.
Me zai faru idan kankara kankara ta narke?
Tare da canjin yanayi da karuwar tasirin greenhouse, akwai maganar narkewar kankara kan iyakoki. Tasirin wannan nan da nan shine matakin tekun zai tashi. Yi la'akari da cewa yawan kankara sun tattara kusan kashi 70% na dukkan tsaftataccen ruwa a duniya. Idan wannan ruwa, abin da yake a cikin farfajiyar ƙasa ya ƙare yana narkewa, zai ƙare a cikin teku.
Masana kimiyya sun kiyasta cewa a shekara ta 2100, matakin teku zai tashi daga matsakaicin santimita 50 daga matakin teku. Wannan yana nufin cewa yawancin biranen bakin teku zasu sami mummunan tasiri kuma sauran tsarin halittu da yawa zasu sake daidaitawa. Bugu da kari, da albedo na duniya Hakanan za'a shafa shi tunda akwai ƙaramin farin fari wanda ke nuna ƙarin hasken rana mai faruwa.
Ina fatan cewa tare da wannan bayanin za ku iya koyo game da iyakokin polar da sakamakon narkar da su.